Figure I Generalized map of the Wilbur Mining ... - University of Utah

Geolêrtnal Resources Council, TRANSACTIONS, Vol. 3 Septetrber 1979 

A REEVALUATION OF GEOTHERMAL POTENTIAL OF THE WILBUR HOT SPRINGS AREA, CALIFORNIA 

ABSTRACT 

In a recent assessment of the geothermal 

potential of the Wilbur Mining District, it was 

estimated that a thennal brine at about 150°C is 

present at depths less than 3 km. The Na-fC-Ca 

geothermometer applied to the four major spring 

groups in this area gives temperatures ranging 

from 220 to 2lOOC. The magnesium corrected 

geothermometer gives inconsistent temperatures 

suggesting that Mg enters the water during its 

passage from the reservoir to the surface. 'For 

this reason the Mg correction is not considered 

appropriate and the fluids are estimated to have 

originated at 230°C. From the CHij, HjS, and 

CO2 concentrations in the spring gases at Wilbur 

Hot Springs and from equations devised primarily 

for use in steam wells, reservoir temperatures 

from 227° to 242°C are calculated. 

INTRODUCTION 

White (1957) suggested that connate water 

underlies the Wilbur Mining District and that this 

water Is affected by low-grade metamorphism of 

J. M. Thompson 

U.S. Geological Survey 

Menlo Park, CA 91025 

deep rocks. This could give rise to the peculiar 

thermal water composition of the four active 

springs in the Wilbur Mining District: Wilbur Hot 

Spring, Jones' Fountain of Life, Blanck's Spring, 

and the Elgin Mine springs. All but the Elgin 

Mine springs issue from the topographic low (see 

Fig. 1) of Sulphur Creek. J. M. Donnelly (oral 

communication, 1979) has mapped a dike of 1.6-m.y. 

andesitic basalt in the vicinity of Wilbur Hot 

Springs. This andesitic basalt is undoubtedly too 

old to be the present day heat source for the 

springs in the Wilbur Mining District, but it may 

indicate that magma or hot rock is still present 

under the Wilbur Mining District. 

GE0THERMC»1ETRY COMPARISONS 

In 1968 a geothennal well, Wilbur SI, was 

drilled to a depth of 1300 m approximately 1 km 

southwest of Wilbur Hot Springs, outside of the 

major thermal activity. White and others (1973) 

reported that this well erupted water at IIOOC. 

A chemical analysis by Sunoco Energy Development 

Company of the well water (Table 1) reported 

^11,loo mg/L Cl, 1500 mg/L higher than that 

reported in White and others (1973). Compared 

Figure I Generalized map of the Wilbur Mining District, Calif. 

• Iivatlon In fttt 

729 

ill

Thompson 

T OC 

pH 

SIO2 

Al 

Fe 

Mn 

Ca 

Mg 

Sr 

Ba 

Na 

K 

Ll 

NHi| 

HCO 3 

CO3 

so^ 

Cl 

F 

Br 

I 

B 

H2S 

Na-K-•Ca 

Mg corr 

SIO2 

Na-K-Ca 

Adlabatic 

Conductive 

Ânalyses,in mg/L 

Table 1. Averaged concentrations for spring and well water 

in the Wilbur mining district' 

Wilbur 

Hot Spring 

52 

7.5 

176 

1.8 

0.17 

O.Of 

2.5 

15 

3.6 

3.1 

8700 

^08 

11.6 

29'* 

6900 

— 

356(H) 

9980 

2.1 

19 

12 

233 

165 

236 

8it 

218 

_—_ 

Jones' 

Fountain of 

Life 

60 

7.7 

89 

0.35 

0.05 

2.6 

31 

1.6 

3.0 

9880 

it 32 

10.7 

120 

57IO 

— 

71 

11,700 

3.5 

31 

23 

2H0 

232 

118 

223 

to Wilbur Hot Springs (see Table 1) Wilbur ffl 

geothennal well contains (1) a higher chloride 

content (11,100 vs. 10,000 mg/L), (2) a lower 

sulfate content (260 vs. 36O mg/L) and (3) a much 

lower magnesium content (2 vs. 15 mg/L). 

The magnesium corrected Na-K-Ca geothermometer 

(Fournier and Potter, 1978) indicates temperatures 

ranging from 10 to 160°C. However, because the 

country rock around Wilbur Hot Springs is 

principally serpentinite, the high magnesium in 

Wilbur Hot Spring is probably due to serpentine 

dissolution. The uncorrected Na-K-Ca (Fournier 

and Truesdell, 1973) temperatures, which range 

from 220 to 218°C, may be more reasonable. 

Water from Wilbur ff 1 geothermal well has a 

Na-K-Ca temperature of 2IIOC (Table 1) and very 

little magnesium; a correction of only 1°C is 

calculated. 

Due to possible silica addition from 

serpentine dissolution, severe difficulties are 

encountered when using dissolved silica 

Blanck's 

Spring 

12 

7.8 

121 

0.19 

0.05 

3.5 

69 

1.1 

1.5 

7220 

360 

6.9 

125 

6390 

— 

180 

8050 

2.3 

21 

18 

150 

730 

232 

16 

198 

—— 

Elgin Mine 

Springs 

61 

198 

0.17 

1.0 

1.8 

28 

3.7 

9330 

510 

11 

213 

7270 

— 

86 

11,550 

3.2 

30 

25 

210 

170 

211 

118 

208 

— •'— 

Wilbur fi 

Geothermal 

well 

110 

8.8 

133 

— 1 

2 

10,000 

110 

— 

275 

5170 

1170 

263 

11,100 

16 

— 

• — 

118 

211 

213 

201 

Meteoric 

water 

19.5 

6.8 

21 

— 3.1 

182 

— 

— 

132 

1.1 

0.16 

— 

1020 

0 

185 

83 

.37 

— 

— 

conoencration in estimating thermal reservoir 

temperatures. The difficulties include the 

following: (1) the silica may have already 

polymerized or precipitated so that direct 

application of the silica geothermometer (Fournier 

and Rowe, 1966) will indicate a low reservoir 

temperature; (2) the thermal water is probably 

mixed with dilute meteoric water giving rise to 

the observed spring water compositions and 

temperatures; and (3) the.diluting water or the 

warm mixed water may contain some silica 

originating from low-temperature serpentine 

dissolution. For comparison, the conductive and 

adiabatic (with assumed subsurface steam loss at 

lOQOC) silica-mixing-model temperatures 

(Truesdell and Fournier, 1977) of the warm springs 

are shown in Table 1. Despite all of the possible 

problems using silica concentrations in springs 

from this area, the adiabatic mixed-water 

temperatures are in moderate to good agreement 

with the Na-K-Ca temperatures. Fournier (1979)' 

indicated that silica reequilibratlon is more 

likely to occur than Na-K-Ca reequilibratlon. The 

—

silica concentration in a water sample from Wilbur 

ffl geothermal well is below that expected in a 

220° to 210OC water; however, It may be in 

approximate equilibrium with quartz at 150°C or 

chalcedony at 13OOC (Truesdell, 1976). The 

quartz equilibrium temperatures at 150OC and the 

Na-K-Ca equilibrium temperatures at 230°C in 

Wilbur ffl are inferred to represent high initial 

water tanperature (230°C) and slow rate of water 

movement. Ultimately, little confidence can be 

placed in the temperatures estimated from the 

dissolved silica concentrations of the springs 

because of the numerous possible complications. 

In an attempt to calculate a third independent 

reservoir temperature, gas samples were collected 

and analyzed. Franco D'Amore and A. H. Truesdell 

(written communication, 1979) have devised a 

system of equations for geothermal steam wells 

which quantitatively relate the concentrations of 

CHi) and CO2 and of H2S and CO2 measured at 

the surface to the temperature in the producing 

zone. Using their equations the reservoir 

temperatures in Table 2 were calculated for Wilbur 

Hot Springs. These temperatures are in excellent 

agreement with the uncorrected Na-K-Ca 

tanperatures from the spring waters. 

Table 2.—Gas Analyses of Wilbur Hot Springs ^ 

Date 12-11- -77 

Collect or AHT 

CO2 

H2S 

NH3 

H2 

Ar 

02 

N2 

CHi) 

C2H6 

TOTAL 

T 

51.2 

2.66 

0.622 

9.36X 

0.319 

U.71 

29.0 

2.36 

0.00 

93.87 

2120C 

Wilb ur Hot Springs 

0-" 

12-11-77 

AHT 

69-3 

2.91 

0.00 

2.66x10" 

0.217 

1.26 

18.8 

3.33 

0.00 

95.85 

237°C 

8-15-78 

JMT 

76.7 

2.92 

, 0.0323 

•^ 1.08x10 

0.188 

0.635 

15.1 

3.28 

0.00 

98.22 

227 °c 

Ânalyses in mole percent. Analyses by Nancy L. 

Nehring, U.S. Geological Survey. 

The Wilbur Hot Springs water composition may 

result if one part diluting water such as that in 

Table 1 mixes with two or three parts of thennal 

water such as that from the Wilbur ffl geothermal 

well. This diluting water may be unusual because 

it contains a high magnesium content from 

dissolved serpentine. Alternatively, the 

magnesium from serpentine dissolution may not 

enter the system until after mixing. Another 

possible scheme is that 230°C water mixes with 

connate water similar to that described by White 

and others (1973) to form the J'ISOOC water in 

731 

Thompson 

Wilbur ffl geothermal well. This water then mixes 

with cold meteoric water in different proportions 

producing the various spring water compositions. 

This model Is not favored because it requires 

three different water types. Presently, the time 

at which the magnesium enters the system cannot be 

determined. The additional sulfate (115 mg/L) 

probably arises from oxidation of H2S in the 

near surface region. 

CONCLUSIONS 

The brine in the Wilbur ffl geothermal well 

result from the mixing of deep thennal water of 

unknown composition at a temperature near 230^0 

and connate water such as that described by White 

and others (1973). Alternatively, the connate 

water may have been heated to near 230°C and 

then mixed with meteoric water in proportions of 

2:1 or 3:1. This diluting meteoric water may 

contain as much as I80 mg/L Mg. This mixed v/ater 

may then slowly rise to the surface without 

appreciable residence in a large reservoir where 

Na-K-Ca reequilibratlon could occur. The depth to 

the 230°C water is unknown. 

REFERENCES 

journier, R. 0., 1979, Geochemical and hydrologic 

considerations and the use of 

enthalpy-chloride diagrams in the prediction 

of underground conditions in hot-spring 

systems: Journal of Volcanology and 

Geothermal Research, v. 5, - 1-I6. 

Fournier, R. 0., and Potter, R. W., II, 1978, A 

magnesium correction for the Na-K-Ca chemical 

geothermometer: U.S. Geological Survey 

Open-File Report 78-986, 2i| p. 

Fournier, R. 0., and Rowe, J. J., 1966, 

Estimation of underground temperatures from 

the silica content of water from hot springs 

and wet-steam wells: American Journal Science 

261,- p. 685-697. • 

Fournier, R. 0., and Truesdell, A. H., 1973, An 

empirical Na-K-Ca geothermometer for natural 

water: Geochlmica et Cosmochimica Acta, 37, 

p. 1255-1275. 

Truesdell, 1976, Summary of Section III 

Geochemical and Geophysical Techniques in 

Exploration: Proceedings 2nd U. N. Symposium 

on the Development and use of Geothermal 

Resources, San Francisco, 19875, v. 1 p 

Ixxiii. 

Truesdell, A. H., and Fournier, R. 0., 1977, 

Procedure for estimating the temperature of 

hot-water component in a mexlco water by using 

a plot of dissolved silica versus enthalpy: 

Journal Reaearch U.S. Geological Survey, v. 5, 

p. 19-52. 

White, D. E., 1957, Magmatic, connate, and 

metamorphic waters: Geological Society of 

America Bulletin, v. 68(12) pt. 1, p. 

1659-1682. 

White, D. E., Barnes, Ivan, and O'Neil, J. R., 

1973, Thermal and mineral waters of nonmeteoric 

origin, California Coast Ranges: 

Geological Society of America Bulletin v. 81, 

p. 517-560.

Geothermal Resources Council, TRAHSACTIOUS, Vol. 3 Septetiiber 1979 

BOREHOLE TEMPERATURE STUDIES OF 

THE LAS ALTURAS GEOTHERMAL ANOMALY, NEW MEXICO 

Paul Morgan, Chandler A. Swanberg 

and Richard L. Lohse 

New Mexico State University 

Box 3D, Las Cruces, NM 88003 

ABSTRACT INTRODUCTION 

Three phases of borehole temperature studies 

have been made relative to the Las Alturas geothermal 

anomaly in southern New Mexico: i) logging 

of "free" holes; ii) shallow gradient study; and 

ill) analysis of data from two 300m tests. A maximum 

temperature of 62.5''C (145°F) has been measured 

at 300m in one of the tests, and the data 

indicate that the source of the anomaly Is a hydrothermal 

circulation system. A simple analysis 

of the temperature data indicate vertical water 

flow rates of the order of 1x10"^ m/s ('»' 1 ft/yr). 

The borehole temperature data have provided valuable 

information for delineating, evaluating and 

characterizing the nature of the source of the 

jnomaly. 

NMSU SUBSURFACE TEMPERATURE 

RESEARCH STUDY 

Geophysical, engineering and economic studies 

all indicate that the Las Alturas geothermal anomaly, 

located adjacent to the city of Las Cruces, 

New Mexico (Figure 1), is a potentially economic 

low temperature geothermai resource for direct 

heat applications at the New Mexico State University 

campus (Gunaji et^ al.-, 1978; Dicey et al. , 

this volume). Borehole temperature studies have 

been made in and around the Las Alturas anomaly in 

three phases: i) regional exploration comprising 

temperature measurements in "free" holes, 11) drilling 

and measurement of 30m temperature gradient 

» , .V I • -r--? ..'I- 

Flg. 1 Index map of that part of Las Cruces, New Mexico, which includes the New Mexico State University 

campus (to the west) and the Las Alturas area (Wells, labeled 6-9). Also shown are the locations 

of the boreholes used for temperature studies. 

469

Morgan, et at. 

holes over the anomaly prior to the siting of 

deeper test wells; and lii) drilling and measurement 

of two 300m test wells. This summary presents 

the results of the three phases of the 

temperature study and the interpretation of the 

subsurface temperature data 

REGIONAL BOREHOLE TEMPERATURE STUDIES 

There are numerous boreholes in the Las 

Cruces area, drilled primarily for domestic water 

supply to depths of a few hundred meters. Eight 

abandoned water wells were available for temperature 

measurements in the Immediate vicinity of 

Las Alturas; the locations for six of these 

(NMSU-1,-2,-3, LAOl, 02, 03) are shown on Figure 1. 

The remaining two wells in the area are located 

off the map, the J. ABRAMS well being approximately 

two miles to the NNW, and DA-1 approximately 

six miles to the east. The temperature data 

from these eight wells are shown tn Figure 2. 

1401- I 

I 

t 

LAS ALTU,=!AS AND 

SURROUNOING AREAS 

TEMPERATURE-DEPTH 

PLOTS 

::.TZ^ Tt5',.S t.'.'C 

iORI20KT,iL ~:-'it 

Fig. 2 Temperature data from "free" boreholes in 

the vicinity of Las Alturas. 

The temperature logs fall Into three distinct 

categories: negative gradients, normal gradients, 

and high gradients. Three wells with negative 

gradients, NMSU-1, NMSU-2, and J. ABRAMS, are all 

located to the west of Interstate-25, which approximately 

divides the Irrigated areas of the Rio 

Grande Valley to the west from the undeveloped 

areas of the mesa to the east. The data from 

these wells clearly indicate recharge of groundwater 

by downward water flow. Three wells east of 

1-25—NMSU-3, LAOl, and DA-1—show reasonably uniform 

positive temperature gradients of the order 

of 40°C/km (2.2°F/100 ft) below a depth of 20 m. 

These gradients are typical of the gradients 

470 

normally measured in sediments in the Rio Grande 

Rift. Two wells at Las Alturas, LA02 and LA03, 

have dramatically higher gradients, of about 

SOCC/km (16.5°F/100 ft), down to the water table 

at approximately 60m, below which depth the gradients 

systematically decrease. These two wells 

provided the first temperature measurements in 

the geothermal anomaly and yielded gradients below 

the water table which indicate that the anomaly 

Is caused by a hydrothennal circulation system. 

In addition, these two wells provided valuable 

information for further temperature studies: 

the high gradients above the water table are 

essentially established in LA02 and LA03 at a 

depth of 10 to 20m, which indicates that 30m is 

an adequate depth for additional temperature 

gradient boreholes. 

SHALLOW GRADIENT BOREHOLES 

A program of shallow temperature gradient 

boreholes was planned to confirm the extension of 

the Las Alturas geothermal anomaly beneath University 

land adjacent to Las Alturas, and to provide 

additional data for site selection for deeper 

tests. On the basis of the temperature results 

from LA02 and LA03, 30m was chosen as the depth 

for the shallow gradient holes. 

Two holes, NMSU-4 and NMSU-5, were initially 

drilled to the east of Las Alturas at the locations 

shown on Figure 1. The temperature data 

from these holes, shown in Figure 3, indicate 

that the anomaly increases to the east of Las 

Alturas. The measured gradients in NMSU-4 and -5 

are 416 and 387°C/km (22.8 and 21.2°F/100 ft), 

respectively. The anomaly is thereby confirmed 

to extend to the east beneath University-owned 

land. 

Data from an earlier electrical resistivity 

study at Las Alturas (Smith, 1977; Jiracek and 

Gerety, 1978) suggest that the anomaly extends at 

least one mile to the north of NMSU-4. Based on 

the resistivity interpretation, the IA02 and LA03 

borehole temperature data, and local geologic 

inforraation, it is thought that the most likely 

origin for the anomaly is a hydrothermal circulation 

system controlled by a KW-J tending fault. 

A profile of four boreholes, NMSU-6, -7, -8, and 

-9, were therefore drilled on an ENE line to the 

north of the proven temperature anomaly to provide 

data for deeper test site selection. The locations 

of the holes are shown in Figure 1. Temperature 

data from these holes (Figure 3) clearly 

define the westem margin of the anomaly with 

gradients increasing to the east as follows: 

NMSU-6, 88°C/km (4.8''F/100 ft); NMSU-7, 320°C/km 

(17.6''F/100 ft); NMSU-8, 446°C/km (24.5°F/100 ft). 

The anomaly appears to peak before the eastern 

hole on the profile, where a gradient of 433°C/km 

(23.8''F/100 ft) was measured, although this is not 

absolutely defined. Unfortunately, institutional 

barriers at this stage prevented the drilling of 

an additional gradient hole to the east. A tentative 

interpretation of all the temperature data 

Is that hot water rises along a NNW striking fault 

to a zone crossing between the two wells NMSU-8 

and -9, and then diffuses laterally. 

r 

s

J 

0 

10 

X 

a. 

^20 

30 

2") 22 

/ 

,/ 

\ 

\ 

\ 

38°C/km-J 

300m TEST WELLS 

\ \ 

\(J1 

24 

K 

Two 300m test wells were drilled on University 

land adjacent to Las Alturas under the supervision 

of L. Chaturvedi of the Civil Engineering 

Department at NMSU. The wells were sited on the 

basis of the interpretation of the data from the 

shallow gradient hole profile, at the locations 

shown in Figure 1, based on the following logic. 

The first test well, DTI, was sited 100m east 

(downdip on the assumed fault) of the apparent 

peak of the anomaly defined by the temperature 

gradient profile. With this well it was hoped to 

intersect and stay in the anomaly source to total 

depth. The second well, DT2, was drilled 0.4 

miles west of DTI along the profile, between 

shallow wells HMSU-7 and -8. This site was selected 

so that if the interpretation of the source 

of the anomaly as a narrow fault-controlled zone 

of rising hot water were incorrect, this well 

would intersect a more laterally extensive source 

at a greater depth from DTI, but at a closer 

distance to the potential user, the NMSU campus. 

If the narrow fault source interpretation were 

correct, however, DT2 would provide information 

about the lateral flow from the system, and act as 

a site for a reinjection well, if required. Wells 

DTI and DT2 were drilled in December 1978 and 

January 1979 and completed as temperature test 

wells at depths of 300 and 360m respectively with 

two-inch water filled casing. 

Temperature data from the two 300m test wells 

are shown in Figure 4. The first well, DTI, 

TEMP CO 

26 28 30 32 34 36 

NMSU SH/lLLOW GEOTHERMAL TEST 

BOREHOLE TEMPERATURE LOGS 

\ , \ ^ ^ 0 \ ^ LOGS WITHIN 72HRS OF DRILLING 

\ V ^ ^ ^ 

\^x 

\ " N V ^ V \ /-446°C/km 

320°C/krn—1 TT L-4 33 .c/km 

Morgan, et al. 

point the gradient becomes negative, indicating a 

heating of the zone around 160m by a lateral flow 

of hot water. Below 275m the gradient in DT2 becomes 

positive again, with the temperature increasing 

to 49.6''C (121°F) at 360m, the base of 

the well. These data clearly Indicate the source 

of the anomaly to be in the vicinity of DTI, with 

a lateral hydrothermal flow towards DT2 to the 

west. The nature of the circulation to the east 

of DTI has not yet been determined. 

The curvature in the geothermal gradient in 

DTI can be used to estimate the vertical component 

of water flow in strata penetrated by the 

well using the relationship 

q = K -7- + pCvdT, 

dz 

(1) 

where q Is the total vertical component of heat 

flow, K is the thermal conductivity of a zone, 

dT/dz is the temperature gradient in the zone, p 

and C are the density and specific heat of water 

respectively, v Is the vertical component of 

water flow velocity, and dT is the temperature 

drop across the zone. By using temperature gradients 

and temperature drops across adjacent zones, 

and assuming q to remain constant, the velocity 

V can be calculated. Using this technique, vertical 

water flows of between 0.3 and 1.4x10"' m/s 

(0.3 and 1.4 ft/yr) have been calculated for the 

DTI temperature data. These calculations assumed 

a density of 1 gm/cm^ for the effective water 

density in equation (1). For absolute water flow 

velocities the numbers given above should be 

divided by the fractional porosity of the strata 

(.12 to .30, L. Chaturvedi, unpublished report). 

Unlike the measured gradients in DT2 and the 

six shallow gradient holes, the gradient in DTI 

shows some curvature above the water table. This 

curvature prevents a direct comparison of the 

shallow gradient in DTI with the gradients In 

NMSU-8 and -9, although its temperature at 30m 

of 34.45°C (94.0°F) is higher than the temperatures 

in the two flanking holes at the same depth, 

34.25°C (93.6''F) and 33.79°C (92.8°F) for NMSU-8 

and -9, respectively. DTI therefore appears to 

be close to the peak of the anomaly, and the 

curvature In the gradient above the water table 

may be due to a significant non-vertical component 

of heat flow close to the shallow source of the 

anomaly. 

CONCLUSIONS AND FUTURE STUDIES 

Borehole temperatures of the Las Alturas 

geothermal anomaly have partially defined the 

lateral extent of the anomaly, provided information 

for the siting of deeper tests, and confirmed the 

source of the anomaly to be a hydrothermal circulation 

system. Modelling of electrical resls- 

• tivity data shows a 5 ohm-m low resistivity zone 

around the peak of the anomaly delineated by the 

shallow temperature gradient data (Sraith, 1977, 

Jiracek and Gerety, 1978), but the borehole temperature 

data have provided the most diagnostic 

472 

information for delineating and interpreting the 

nature of the geothermal anomaly. 

During the next few months it is planned to 

drill a deeper test well, up to 750m deep, into 

the geothermal system (L. Chaturvedi, personal 

communication). Further shallow gradient holes 

are planned over the center of the anomaly to 

provide information for the siting of this well. 

An extension of the heat flow analysis outlined 

above indicates a further decrease in the gradient 

below 300m, with the temperature possibly 

increasing to as little as 1 to 4''C (2 to 7*F) 

at 750m, giving a bottom hole temperature in the 

range of 64 to 67''C (147 to 153°F). This analysis 

assumes that the vertical water flow rates 

estimated for the zone from 300m up to the water 

table are representative of the flow rates below 

300m. If this analysis is correct, the source of 

the hot water for the hydrothermal system could 

be groundwater circulation down to a depth of a 

little over 1 km, with a geothermal gradient 

typical for the area (40°C/km, 2.2°F/100 ft). 

This extrapolation of the data uses many as yet 

unproven assumptions, however, which only the 

drilling of the third deep well can test. 

ACKNOOT.EDGEMENTS 

Funds for drilling the six shallow gradient 

holes were arranged by H. A. Daw of the New 

Mexico Energy Institute at NMSU- 

REFERENCES 

Gunaji, N. N., Chaturvedi, L., Thode, E., 

LaFrance, L., Swanberg, C. A., and Walvakar, 

A., 1978, A geothermal field near New Mexico 

State University and its potential as a 

campus energy supplier, Geothermal Resources 

Council, Transactions, v. 2, p. 241-244. 

Jiracek, G. R., and Gerety, M. T., 1978, Comparison 

of surface and downhole resistivity 

mapping of geothermal reservoirs in New 

Mexico, Geothermal Resources Council, 

Transactions, v. 2, p. 335-336. 

Smith, C., 1977, On the electrical evaluation of 

three southern New Mexico geothermal areas, 

unpublished M.S. thesis. University of New 

Mexico, Albuquerque, New Mexico, 110 p. 

* 

m 

• «

Geothennal Resources Council, TRANSACTIONS, Vol. 3 Septetrher 1979 

CONTINUOUS GRAVITY OBSERVATIONS AT THE GEYSERS:. A PRELIMINARY REPORT 

ABSTRACT 

A cryogenic gravimeter has been installed at 

The Geysers to continuously monitor gravity variations 

at the Mgal level. A 38-day record is presented 

to illustrate the type of information that 

can be obtained from such an instrument. In 

addition to information directly related to mass 

transport within the reservoir, the data reveal a 

sudden 6 ygal decrease in gravity prior to a local 

earthquake. We also observe a 5 ugal increase in 

gravity during a heavy rainfall; however, interpretation 

of gravity variations at this level is 

limited by uncertainty in tilting of the gravimeter 

pier. The potential Irapact of continuous 

gravity observations on the study of reservoir 

characteristics is discussed. 

THE CRYOGENIC GRAVIMETER 

Jeffrey J. Olson and Richard J. Warburton 

University of California at San Diego 

La Jolla CA 92093 

Although cryogenic gravimeters have been in 

existence for several years (Goodkind and Prothero^ 

1968, and Warburton and Goodkind, 1978), this is 

the first use of such an instrument in a geothermal 

application. The instrument differs from conventional 

gravimeters in that mechanical springs 

and levers are replaced by magnetic fields generated 

from persistent currents in colls of superconducting 

wire. These fields support a one-inch • 

dlamecer superconducting sphere (the graviroeter's 

only moving part) with a force that does not 

significantly diminish in time, due to the persistence 

of superconducting currents. Thus the 

cryogenic gravimeter does not exhibit the instrumentally 

produced signal drift which is characteristic 

of conventional gravimeters. Several years 

of gravity observations at Pinon Flat in southern 

California indicate that the total Instrumental 

drift is 0 ± 5 ygal/yr. A planned side-by-side 

test of two cryogenic gravimeters at Pinon Flat 

should determine whether this residual variation 

is of instrumental or geophysical origin. 

The short term precision of the cryogenic 

gravimeter appears to be limited only by the uncertainty 

with which the contributions frora known 

sources such as earth and ocean tides and atmospheric 

density variations can be subtracted. The 

data presented below indicate that this can be 

accomplished empirically to a precision of ±1 

ligal. Spurious tilting of the gravimeter platform 

can degrade this performance, but tilt will soon 

be controlled by the addition of an automatic 

519 

leveling system. 

OBSERVATIONS AT THE GEYSERS 

A cryogenic gravimeter was installed in 

February of 1979 in The Geysers steam field at 

latitude 38° 48' 25" and longitude 122° 48' 50". 

This site is on a spur of ridge which extends 

downward from Well Sulphur Bank 19 toward Units 3 

and 4. McLaughlin (1974) maps this general area 

as a quaternary landslide, however, the spur 

appears to be an outcrop of relatively unfractured 

Franciscan graywacke. Weathered graywacke 

slightly uphill of the outcrop was excavated to a 

depth of 2 - 3 m to expose bedrock, upon which a 

3 m high reinforced concrete pier was erected. 

The gravimeter platform rests on this pier, supported 

on three points two of which are heavy 

duty micrometer heads to allow alignraent of the 

gravimeter with the vertical. The active element 

of the gravimeter is immersed in liquid helium in 

a Dewar which is fixed to the platform. 

The output signal from the gravimeter is in 

the form of an analog voltage which is filtered 

electronically for sampling at a variety of rates 

from 20 seconds to 15 minutes. Barometric 

pressure as measured by a temperature regulated 

aneroid barometer is also filtered and monitored 

at 15 minute intervals. These signals are recorded 

in the field on digital tape cassettes by a 

microcomputer-controlled data system, which can 

also transmit stored data by telephone to our laboratory 

for inspection. 

A sample of raw data together with the results 

of various stages of its reductiori are shown 

in Figure 1. All four graphs are plotted as 

functions of time at 15 minute Intervals beginning 

at 067:00:00:00 UTC and ending 38 days later at 

105:00:00:00 UTC. The observed gravity signal, 

Figure la, is dominated by smooth tidal variations 

(the coarseness of this graph is an artifact of 

the digital plotter: the point density is nearly 

1000 points per inch on this scale). The principal 

component of this signal is the direct gravitational 

attraction of the moon and sun together 

with the effects of deformation of the earth's surface 

due to tidal forces and loading from ocean 

tides. These tidal effects contain little information 

relevant to the geothermal reservoir and 

must be removed before local effects can be observed. 

This can be accomplished by subtraction

Olson, et al 

of a theoretically generated tide signal, to 

account for the direct attraction effects, followed 

by least squares removal of the strongest remaining 

tidal spectral components, to account for 

ocean loading effects. 

The resulting detided gravity signal is shown 

in Figure lb; the upward direction on the plot 

corresponds to increasing strength of gravity. . 

The detided gravity signal contains variations of 

up to 13 ligal over a few days; however, most of 

this is due to large scale atmospheric density 

fluctuations associated with the motion of weather 

systems, as is evident from comparison with the 

barometric pressure record. Figure Ic. The upward 

direction on this plot corresponds to decreasing 

pressure, thus the central peak in Figure Ic in-f 

dlcates a strong low pressure system. Superimposed 

on these major variations are minor oscillations 

due to the global semidiurnal atmospheric 

tides and local pressure fluctuations. As demonstrated 

by Warburton and Goodkind (1977), gravity 

effects due to major barometric pressure fluctuations 

can be removed from the detided gravity signal 

by least squares subtraction of the barometric 

pressure signal. The fitting coefficient yields 

an empirical barometric pressure admittance, which 

in this case amounts to 0.27 ygal/mbar. In other 

words, as much as 9 ligal of the detided gravity 

variations in Figure lb were due to atmospheric 

effects. 

Removing these atmospheric effects produces 

the residual gravity signal shown in Figure Id. 

As in the other plots, a decreasing signal implies 

decreasing strength of gravity as occurs during 

mass extraction or surface uplift. Several features 

which were previously obscured by atmospheric 

effects are now apparent. Most remarkable 

of these is the sudden drop of nearly 6 vigal which 

occured on day 078. Closer scrutiny on an expanded 

scale reveals that the drop was not instantaneous: 

the gravity decrease was linear in time over 

a two and one-half hour period. Moreover, a separate 

high frequency output channel from the 

gravimeter indicated no unusual seismic activity 

or disturbance of the Instrument during this 

period; the decrease was quiet and gentle. However, 

two hours after this gravity change had 

ceased, the high frequency channel shows a local 

earthquake, which, according to Bufe (unpub. data) 

was of magnitude 3. The sign and magnitude of 

this gravity event are consistent with an uplift 

of the gravimeter by approximately 2 cm. 

The second noteworthy event in the residual 

•VW^'V''^\Ayv.,^^-V ^"^^^^ 

^ • ^ ' ' ^ ^ ' ' ^ ' ' ' ^ ^ ^ ^ ' ^ ^ 

070 075 080 085 090 095 100 105 

(a) observed 

gravity 

(b) detided 

(c) barometric 

pressure 

(d) residual 

gravity 

Figure 1. A 38-day data segment from The Geysers, illustrating the extraction of a 

barometrically adjusted residual gravity signal from the raw gravity and 

barometric pressure signals. 

520

gravity signal is a rapid but Irregular 5 pgal increase 

beginning on day 086. This increase in 

gravity occurs over an 18 hour period which coincides 

precisely with the duration of the only significant 

rainfall In this 38 day data segment. 

Analysis of rainfall effects in barometrically 

adjusted gravity residuals is simplified by the 

fact that there is a slight decrease in barometric 

pressure directly associated with the release of 

mass from the atmosphere. This decrease in 

pressure equals the weight per unit area of the 

released mass. If we let Ag represent the gravitational 

attraction of a sheet of water of thickness 

equal to the depth of rainfall, then it can 

be shown that the barometric pressure correction 

used to produce Figure Id contributes an amount 

-Ag to the residual gravity signal starting at the 

time of the rainfall. Thus the net result of rainfall 

on barometrically adjusted gravity is simply 

to produce an apparent change by an amount -Ag if 

the sheet of water comes to rest above the gravimeter, 

or +Ag if the sheet lies below the gravimeter. 

In both cases, these changes vanish as 

the water in question drains away from the vicinity 

of the gravimeter. Considering the terrain 

at The Geysers we would expect a zero change in 

the present case, or, at most, a change of +2 

ugal. Thus the 5 ygal observed change appears to 

be a spurious effect, most likely due to tilt. 

That tilt influences gravity measurements is 

a direct consequence of the vector nature of the 

gravitational field. If one assumes that a gravimeter 

tilted by an angle 6 frora the local 

vertical simply raeasures the component gcos9, the 

theoretical tilt response to lowest order in 8 is 

-1/2 pB^ or -4.6 x IO""* ugal/uradian^; i.e., the 

gravimeter will read a maximum value when aligned 

with the vertical. This, however, is not the 

case for the cryogenic gravimeter. The magnetic 

field geometry currently used to levitate the 

test mass inside the instrument causes the tilt 

response to have a larger magnitude and opposite 

sign compared to the naive estimate. The actual 

tilt response of The Geysers instrument is 

+ 5.9 X 10-"* Mgal/pradian^. Thus the gravimeter 

reads a minimum value when vertical and deviations 

frora the vertical will tend to Increase the apparent 

value of g. Tilts of 40 yradians (1 ugal) 

would be observable and tilts of 100 yradians 

( 5.9 ugal) would be sufficient to explain events 

such as seen in Figure Id. The planned automatic 

leveling system should limit tilt to less than 

10 uradian (0.06 ugal). 

In spite of the problens in Interpreting the 

two rapid changes in gravity in this record, the 

general trend of the gravity residual In Figure Id 

shows a slow decrease of 4,5 ± 0.5 pgal over the 

38 day segment. Extrapolating this trend yields a 

rate of decrease In gravity of 43 ± 5 wgal per 

year, which is in close numerical agreement with 

the average rate of decrease of 46 + 7 ygal per 

year Inferred from Isherwood's 1974 and 1977 

gravity surveys (Isherwood, 1977). Isherwood 

showed that this decrease could be explained by 

the mass deficiency generated by steam production 

over that two and one-half year period. The close 

agreement of these two measurements is most likely 

521 

Olson, et al 

fortuitous, considering that Isherwood's data represent 

a yearly averaged effect, that the data 

were collected during two drought years, and that 

steam production has changed between 1977 and 1979. 

The agreement, nevertheless, indicates that the 

cryogenic gravimeter raay be capable of producing 

results in one month that might take years to 

accomplish with conventional gravimeters. 

GEOTHERMAL IMPLICATIONS 

Although the data presented here are insufficient 

to yield new conclusions at this time regarding 

reservoir dynamics, they do demonstrate 

that the cryogenic gravimeter has both the sensitivity 

and the stability required to produce new 

results. The continuous nature of gravity observations 

made feasible by this type of instrument 

enormously expands the interpretative power of 

gravity studies. With the addition of a tilt 

stabilized platform, events which would otherwise 

be obscured by long term averaging can be detected 

and events whose contributions to the total gravity 

change would otherwise be indistinguishable can 

be separated and identified by their time signatures 

and correlations with other events. 

Even the short data segment presented here, 

despite its tilt uncertainties, indicates that we 

will be able to accurately observe the steady decrease 

in gravity associated with continuous steam 

production and thus provide the most direct available 

raeasure of reservoir recharge. The accuracy 

of these estimates will be further enhanced by our 

ability to separate out those sudden effects which 

appear to be unrelated to mass depletion. It is 

not unreasonable to expect that meaningful estimates 

of recharge may ultimately be obtained from 

as little as 90 days of gravity observations, 

thereby enabling study of seasonal fluctuations 

as opposed to multiyear averages. 

Furthermore, it may be possible to detect 

short term mass redistributions within the reservoir 

that could accompany changes In steam production 

or changes in reinjection, thereby yielding 

Information regarding the percolation-condensation 

cycle of steam within the reservoir. In 

addition, gravity events which are correlated 

with seismicity could provide clues regarding 

earthquake mechanisms at The Geysers and their 

possible relation to reservoir exploitation. 

ACKNOWLEDGEMENTS 

We thank Richard Dondanville and the staff of 

the Geothermal Division, Union Oil Company, for 

their cooperation and assistance, especially 

during the installation of the site, and Richard 

Reineman for his technical expertise in fabricating 

the gravimeter. This work is funded by the 

United States Geological Survey through the Extramural 

Geothermal Research Prograra under Grant 

USDI-14-08-0001-G-297. 

REFERENCES 

Goodkind, J. M. and Prothero, W. A. Jr., 1968, A 

Superconducting gravimeter. Rev. Sci. Instr. 

v..39, "p. 1257.

Olson, et al 

Isherwood, W. F., 1977, Geothermal reservoir interpretation 

from change in gravity. Workshop 

Geothermal Reservoir Engineering, 3rd, 

Stanford, Calif., Proceedings, p. 18. 

McLaughlin, R. J., 1974, Preliminary geologic map 

of The Geysers steam field and vicinity, 

Sonoma County, Calif.: U. S. Geol. Survey 

Open-file Map 74-238. 

Warburton, R. J. and Goodkind, J. M., 1977, Influence 

of barometric pressure variations on 

gravity, Geophys. J. R. Astr. Soc, v. 48, 

p. 281. 

Warburton, R. J. and Goodkind, J. M., 1978, Detailed 

gravity-tide spectrum between one and 

four cycles per day, Geophys. J. R. Astr. 

Soc. V. 52, p. 117. 

522

Geothermal Resources Council, TRANSACTIONS, Vol. 3 Septetrher 1979 

THE INFLUENCE OF STEAM-WATER RELATIVE PERMEABILITY CURVES ON 

THE NUMERICAL MODELING RESULTS OF LIQUID DOMINATED GEOTHERMAL RESERVOIRS 

ABSTRACT 

Sensitivity analyses for modeling of a hypothetical 

liquid dominated geothermal reservoir 

indicate the strong dependence of the results on 

the assumptions made about the steam-water 

relative permeability curves. Of significant 

importance are the critical saturation points for 

the individual phases and the curvature of plots. 

The effects are more evident on calculated 

producing wellbore pressure and projected heat 

recovery. 

INTRODUCTION 

The success of numerical modeling for hydrothermal 

systems depends on the assumptions raade 

about the rock and fluid property data. One piece 

of information that strongly controls the results 

of model studies for two phase flow in reservoirs 

is the assumed values for relative permeabilities. 

A review of literature shows that in previously 

published model studies on geothermal 

systems, the concept of relative permeability has 

been treated lightly, perhaps because of lack of 

information. Relative permeabilities used in the 

past include systems similar to oil-water models 

as used by Martin', or approximations by simple 

models such as Corey's^ as used by Faust and 

Mercer,^ Jonsson'' from his modeling work 

indicated that relative permeability data had 

little influence on pressure drop and saturation 

d istr i but ion. 

Recently, evidence of actual lab derived 

relative permeability curves for steam-water 

systems has appeared in the literature.^ * These 

curves show that the end points, corresponding to 

the critical water and critical steam saturation, 

may be much different than the ones used in oilwater 

or water-gas system. 

In this study an effort was made'to look at 

the sensitivity of numerical modeling results to 

the assumed values of relative permeability data. 

DESCRIPTION OF THE MODEL 

The numerical model used in this study was a 

modified version of a program originally developed 

by Faust and Mercer. Relative permeability curves 

H. Sun and I. Ershaghi 

University of Southern California 

697 

were furnished to the program through the use of 

an equation which allowed for selection of a 

wide range of end points as well as curvatures. 

The general form of the equation may be shown as 

follows: 

(S - S ) 

'I 

w wc 

b (1 S - S ) 

W SC 

where S = water saturation, fraction 

w 

S = critical water saturation, fraction 

WC 

S = critical steam saturation, fraction 

SC 

a, b, n and n are constants. 

The model was used for a one dimensional 

reservoir initially containing hot water with 

one producing well and no recharge. The heat 

and mass recovery as a function of time were 

computed using different sets of relative permeabilities. 

Table I shows some of the specifications 

used in the model. 

Throughout the life of the system, flow 

toward the wellbore occurs in three distinct 

periods. The initial period of single phase 

liquid flow, followed by a two phase liquid-vapor 

flow and the eventual conversion to one phase 

vapor flow. In assessing the importance of 

accurate relative permeability data on modeling 

. results, one must examine the outputs which can 

be used for history matching purposes. The study 

of saturation distribution and other profiles in 

the reservoir as used by Jonsson may be somewhat 

mi sleadi ng. 

There are several ways to use numerical 

modeling results for history matching purposes. 

The results of this study are presented in terms 

of heat recovery versus time and wellbore 

producing pressure versus time. 

The effect of assumed values for critical 

saturation of water is shown in Fig. 1. During 

the two phase flow, the Change of critical water 

saturation from 0,3 to 0.5 could cause significant 

differences in the performance projection for 

1' 

i! 

I I 

,1

Sun and Ershaghi 

history matching purposes. 

Similar effect s for the changes in critical 

point of the steam is shown in Fig. 2. Variation 

of the end point fo r steam has a somewhat smaller 

effect on estimated heat recovery. For systems 

with recharge or re injection there is no need to 

be concerned about the accurate location of end 

point of steam re I a tive permeability curve, 

Effect of the curve ture of relative permeability 

curves on the heat recovery projection is shown 

in Fig. 3 and is of considerable importance. 

A more dramatic effect is seen on the wellbore 

producing pressure versus time. Significant 

differences may be observed on the behavior of the 

pressure curve if the critical water saturation or 

the curvature of relative permeability curves are 

varied. Fig. 1-5. The sensitivity of pressure 

calculations to steam critical saturation and end 

points are somewhat less. 

CONCLUSION 

The influence of steam-water relative permeability 

data on numerical modeling results for 

geothermal system is significant enough to require 

more accurate estimates of critical points than 

that practiced in the past. 

Because of ambiguity about the exact nature 

of steam-water relative permeability curves and 

contradicting published values about the location 

of critical points and based on the results of 

this study, it is imperative that more attention 

be focused on actually measured relative permeability 

curves. Field and laboratory derived 

curves must be carefully examined for establishment 

of representative relative permeability data. 

Table Basic reservoir properties 

Pore Volume = 50 x lo'^ cc (1.78 x lo' cu ft) 

Production Rate = 20 x lo' g/sec (J60,000 Ib/hr) 

Permeability = 0,1 x 10"' cm^(10 md) 

Initial Pressure = 1.925 x 10^ dynes/cm^ (711 psi) 

Initial Temperature = 236,I2°C 

REFERENCES 

1. Martin, J. C: "Analysis of internal steam 

drive in geotherraal reservoirs." J. Pet. Tech. 

(Dec. 1975) 1193-1199. 

2. Corey, A. T,: "The interrelation between gas 

and oil relative permeabilities." Producers 

Monthly, V. 19 (1951) p, 38-11. 

3, Faust, C. R, and Mercer, J. W.: "Finite 

difference model of two dimensional singleand 

two-phase heat transport in a porous 

medium Version 1." open file Rep. 77~23l, 

698 

t 

81 pp., U.S. Geol. Surv., Reston, VA.(1977). 

1. Jonsson, V.: "Simulation of the Krafla 

geothermal field." Earth Science Division, 

Lawrence Berkeley Laboratory, University of 

California Berkeley, LBL-7076 (Aug. 1978). 

5. Chen, H. K., Counsil, J. R. and Ramey, H. J. 

Jr.: "Experimental steam-water relative 

permeability curves." Geothermal Resources 

Council, Transactions, Vol. 2 (July 1978). 

p. 103-10^: 

6. Home, R. N, and Ramey, H. J. Jr.: "Steam/ 

water relative permeabilities from production 

data," Geothermal Resources Council, 

Transactions, Vol. 2, (July 1978) p. 291-293. 

>rc 

u 

> 

o 

o 

UJ 

tx. 

I- < 

UJ 

I 

16 

14 

12 

10 

Swc= 0.3 

Swc= 0-5 

0 \y I I I I I I I I I 

0 2 4 6 8 10 12 14 16 

TIME (x 360 DAYS) 

Fig, I Effect of S on hea 

wc 

t recovery vs. time.

13 

12 

II 

10 - 

7 

>cc 

111 

S 6 

o 

Ssc=0-4 

Ssc = 0.25 

0 2 4 6 8 10 12 

TIME (x360 DAYS) 

Fig, 2 Effect of S on heat recovery vs, time. 

699 


0 2 4 6 8 10 12 14 16 


Fig, 3 Effect of curvature on heat 

recovery vs. time. 

! II 

^ I'll


eg 

S 

o 

"^ 

lii 

z 

>o 

r^ o 

ac 

V) 

tn 

UJ 

o: 

a. 

3,0 

2.0 

1,0 

0 

^ 

\ 

^C 

Swc = 0-5^ 

^ wc 

1 1 1 

2 4 6 8 10 12 14 


Fig. 1 Effect of S„j. on wellbore producing 

pressure vs. time. 

CM 

o 

UI 

z 

>oto 

UJ 

«. 

-i 

Ji 

CO 

UJ 

tr 

a. 

3,0 

2.0 

1,0 

0 

- 

,^ 

\- 

\ \ 

V N = I0V 

\ 

^ . N = 2 

N= 3^^>. 

1 1 1 1 1 

0 2 4 6 8 10 12 14 


Fig. 5 Effect of curvature on wellbore 

producing pressure vs, time. 

700

Geothermal Resources Council, TRANSACTIONS, Vol. 3 Septetrber 1979 

KLAMATH FALLS GEOTHERMAL HEATINR DISTRICT 

John H. Lund. Paul J. Lienau. G. Gene Culver. Charles V. Hiqbee 

ABSTRACT 

The City of Klamath Falls is proposing to 

construct a geothermal district heating project. 

Initially, the systera will heat 14 governraent 

buildings (Phase I) in the downtown area, subsequently 

expanded to heat 11 blocks (Phase II), 

and then to heat the entire 54-block central 

business district (Phase III). Production wells 

will be drilled along the east boundary of the 

City, estimated to supply over 220°F water. A 

primary 8-inch diameter insulated steel pipeline 

placed in a concrete tunnel will supply geothermal 

fluid to a central heat exchange facility at the 

County Museum Building. Two plate heat exchangers 

will provide the necessary load for the initial 14 

buildings. An injection well is located next to 

this facility. A closed loop secondary pipeline 

will supply heat to the 14 buildings at 200°F. 

This line will consist of buried insulated fiberglass 

reinforced pipe. The capital cost of the 

system (Phase I) will be $1.4 million giving an 

equivalent annual capital, operation, and maintenance 

cost over a 20-year period of $150,000. 

Phase II cost of geothermal energy is estimated 

at $0.29 per therm, whereas the equivalent 

annual fossil fuel cost is estimated at $0.94 per 

therm. 

INTRODUCTION 

The purpose of the 1977 Field Experiment 

contract awarded under PON EG-77-N-03-1553 to the 

City of Klamath Falls, Oregon, is to design, construct, 

and initiate operation of a geothermal 

space heating district in the central business 

district of the City. This direct utilization 

project is for a City-owned and operated system, 

initially serving 14 City. County, State, and 

Federal office buildings (Phase I), with initial 

expansion to serve 11 blocks of commercial buildings 

along the pipeline route for the 14 buildings 

(Phase II), with subsequent expansion to commercial 

buildings on 54 city blocks in the central 

business" district (Phase III). The project will 

include production wells, injection wel1(s), 

transmission lines, controls, and retrofitting 

equipment for the governmental buildings. 

LLC Geothermal Consultants 

Klamath Falls. Oregon 

381 

PART I 

GEOLOGY. DISTRICT BOUNDARIES, & PRODUCTION FIELD 

Geology and Hydrology 

The Klamath Falls KGRA is located near the 

east side and center of the Klamath Basin, a 

northwesterly-oriented graben. The Klamath Falls 

urban area is located in the northern and largest 

portion of the KGRA. The main hot water well 

area is located adjacent to the eastern fault 

scarp, over fault blocks that are slightly 

tilted and raised above the central portion of 

the graben (Figure 1). The principal geologic 

formations are lava flows, volcanic breccia 

(including labilli), locally designated "cinders," 

and extensive deposits of lacustrine diatomite 

and tuffaceous siltstones and sandstones. 

\ofi^GON_iNSTt r.ur^ 

.£Lt. W.rkU T£M.r..TUIt£ 

,17 4000' CLCVATIOH 

wareit WELL AREA 

NOAftr lrEup>i00'f.i 

ISO' f. tVATER 

\ aouKOdRr 

ZOO'r WATER 

BOUNDARr 

FIGURE 1 

Well Water Temperature at 4000' Elevation

« 

•'t 

Lund. et. al. 

In general, the fractured basalts and 

cinders are highly porous, being capped by a 

nearly impervious zone of fine grained, lacustrine, 

palagonite-tuff sediments and diatomite, referred 

to as the "Yonna formation" and locally as 

"chalk rock." This formation, Tst on the geologic 

map. is estimated to be 30 to 150 feet 

thick in the urban area. It is also interbedded 

with sandstone or siltstone and fine 

cinders. 

The hot water probably originates from the 

Cascades to the west and Crater Lake area to the 

north. Deep circulation of the water is speculated, 

with the heated water upwelling along the 

east-side fault in the urban area (Hot Springs 

District), and then flowing in near horizontal 

aquifers to the southwest. Contours of static 

well water elevations indicate a hydraulic 

gradient of from 0.5 to 3 percent sloping to the 

west and southwest. In almost all cases, the 

geothermal water is found in confined aquifer 

thus producing an artesian pressure head. 

Maximum temperatures are found in the 

vicinity of the main fault, with up to 235°F 

being recorded. Temperatures tend to decrease 

down gradient to the southwest, probably due to 

cooling with time in the aquifer and mixing with 

colder shallow ground water. 

Geothermal wells drilled in the area vary 

from 90 feet to slightly over 2000 feet in depth. 

Short term pumping has produced up to 700 gpm 

(County Museum well), from a single well with 

500 gpm (OIT) being pumped on a sustaned basis. 

Water levels and well temperatures will vary 

with time, mainly on a seasonal basis. With 

usage during the heating season, water levels 

will drop and temperatures increase. During dry 

periods (late fall) water levels have also been 

known to drop markedly, most noticeable in 

artesian wells. Temperature variations of up to 

30°F and water level variations of 20 feet are 

not uncommon. 

The majority of the approximately 500 wells 

in the urban area use down-hole heat exchangers 

to provide space heating and domestic hot water, 

thus only "heat" is extracted from each well. 

Approximately 55 of the 500 wells pump the geothermal 

water from the well to be used in surface 

heat exchangers and then the fluid is disposed of 

on the surface (storm sewer, sanitary sewer, 

etc.). The total hot water extracted in the urban 

area is approximately 2110 gpm in the winter and 

340 gpm in'the summer. Three cases of successful 

fluid injection are known in the urban area, all 

within 500 feet of their production well area. 

District Boundaries 

Boundaries of the pumping districts for the 

geothermal distribution system were determined 

for the urban area. Special attention was given 

to the boundary for the central business district 

(referred to as the "Commercial District"), 

382 

as Phases I. II, and III design were dependent 

upon the heat load in this district. The 

remaining districts had their boundaries only 

approximately located, since their exact heating 

load was not required for this project. Their 

location and approximate size would however, be 

used to locate pipelines and heat exchanger 

facilities'of the Commercial District for 

possible future expansion. In addition, certain 

potential well production areas and storage tank 

areas could be reconmended based on district 

locations. 

The boundary of the Commercial District was 

determined based on four criteria: 

1. location of the supply line for the 14 

government buildings; 

2. the location of private commercial buildings 

in the downtown central business district; 

3. the location of a proposed mini-heating district 

for 10 church complexes in the downtown 

area; and 

4. consultation with City of Klamath Falls 

officials. 

Based on the above criteria, slightly over 50 

city blocks in the downtown area were included 

in the Commercial District. This area extended 

from the County Museum (location of the proposed 

heat exchanger building) to Veterans Memorial 

Park, varying from 1 to 8 blocks wide and 

including all but 1 church in the original miniheating 

district design. A summary of the heat 

load calculations of this district for Phase I 

and II are as follows: 

Phase I (14 government buildings) 

Peak heat load 15 x 10^ BTU/hr 

Geothermal flow rate 756 gpm (assuming 

40°F AT) 

Phase II (11 cotmtercial blocks) 

Peak heat load 28 x 10^ BTU/hr 


40°F AT) 

Phase III (entire Commercial District) 

Building volume 30 x 10^ ft^ 

Unit peak heat load 4.34 BTU/ft^ 

Peak heat load 

(space) 130 x 10^ BTU/hr 

+(process) 5 x 10^ BTU/hr 

Total 135 X 10& BTU/hr 


40°F AT) 

The remaining district boundaries in the 

urban area were then located. These boundaries 

were based on four main criteria: 

1. natural topographic features; 

2. man-made features; 

3. political boundaries; and 

4. land use.

Natural and man-made features were the primary 

controlling items. These included the two 

lakes, Link River, main ridge lines, the railroad 

and the "A" canal. Any of these items would be 

costly to cross. For this reason the local 

distribution system for a district should fall 

within these boundaries and only major supply 

lines would cross thera at carefully selected 

points. City political boundaries did control 

the district locations to a degree, mainly to 

simplify future administration. 

Figure 2 is a generalized map of the urban 

area showing the approximate district boundaries. 

The district areas increase with distance from 

the central business district, due to the reduction 

in heating (population) density in the 

suburban areas. Heating loads for each district 

have not been determined, however it is estimated 

that the majority are approximately equal. 

FIGURE 2 

Heating District Boundaries 

Based on discussions with City planning 

officials, a priority was given each district 

as to its probable inclusion into the system. 

Thus districts labeled "1" on Figure 2 would be 

developed first. "2" second, and so forth. Districts 

with priorities "1" and "2" have their 

boundaries fairly precisely determined for planning 

purposes, whereas priorities "5" and "6" have 

more flexible boundary locations due to the possible 

effects of future growth before these districts 

come on-line. 

303 

Lund, et. al. 

A probable development schedule for each of 

the priorities would be as follows: 

District Priority Tirae of Development 

1 

2 

3 

4 

5 

6 

0-2 years 

2-5 

5-10 

10-15 

>15 

>20 

It should be noted that two of the Districts 

immediately adjacent to the Commercial District 

were given a low "4" priority for development. 

This recognizes the fact that a great portion of 

these districts are already heated by individual 

wells, thus some of its heating needs are already 

being met by geothermal. Future development may 

be based on either expanding the service load of 

each existing well (from one to four houses, for 

example), or by providing a heating district 

similar to the other districts. 

Production Field Locations 

Several areas near or in the urban area have 

potential as production well sites. Each area 

was evaluated as to certain desirable characteristics, 

which included: 

1. proximity to users so as to minimize supply 

pipeline lengths; 

2. elevation head to provide gravity feed; 

3. availability of public land for development; 

and 

4. information on geothermal fluids existing in 

or adjacent to the site. 

Based on the above criteria and geologic information, 

seven areas have potential to supply the 

necessary fluids for the near term or future 

development of the area. In many cases, additional 

geological, geophysical exploration, and/or 

drilling need to be performed to verify the 

existence and characteristics of the resource. 

Figure 3 is a map to the same scale as the 

geologic map indicating the seven sites. The 

numbers also indicate the order of recommended 

investigation and development of the sites. Site 

1 is discussed in detail.

Lund. et. al. 

FIGURE 3 

Production Fields 

IUNGS1.EV 

FIELD / \ 

Site 1 is located adjacent to Old Fort Road 

on the City boundary. It is situated approximately 

on the major fault zone, the source of the 

majority of the geothennal fluids for the area. 

Several geothermal wells exist in the area, the 

majority of which are 200 to 400 feet in depth with 

with one being 795 feet deep. The hottest temperatures 

known in the urban area are found here as 

indicated by one shallow "steamer" and the deep 

well having a bottom hole temperature of 234°F. 

The potential exists for the City of Klamath 

Falls to acquire wells and/or land in the area 

for development of the field. The City also has 

a small triangular piece of land near the intersection 

of Laguna Street and Old Fort Road that 

could provide a drilling site for one well. 

The site has good elevation head above the 

central business district and a good easement 

for a pipeline along streets at a fairly uniform 

grade. The main disadvantage of the site is 

that approximately 15 to 20 shallow residential 

wells exist within 1500 feet of the most likely 

drilling sites. These shallow wells could be 

affected by long-term pumping of production 

wells. The area is also limited as to the total 

number of production wells that could be drilled 

due tominimum spacing, however, the demand for 

384 

the 14 government buildings (756 gpm) could 

easily be supplied. The total demand for the 

"Commercial District" (6750 gpm) could 

probably not be supplied by this field and the 

availability of land and wells to the City. 

The location near the main fault zone would 

give this site the best priority for production 

wells. 

Pump Test 

During July. 1978, a pump test was performed 

on the 795-foot deep well in Site 1. This well 

has a 14-inch diameter casing to 229 feet and 

static water level at about 75 feet below the 

surface. Bottom hole fluid temperature has 

been measured at 234°F, and dry rock temperatures 

reported as high as 250°"F. It is estimated 

that this well is drilled into or is very near 

the major fault zone of the area. Twelve observation 

wells were selected within 1500 feet of 

the production well. Unfortunately, no well in 

the area extended.to the same elevation depth as 

the production well. 

Each of four phases of the test lasted 48 

hours: 

1. pumping without injection (water wasted to 

the sewer); 

2. rebound; 

3. pumping with injection; and 

4. rebound. 

Personnel from LBL and OIT students assisted in 

the project. 

Observations: 

1. Maximum production rate was 300 gpm at 100 

foot drawdown. 

2. Maximum surface flow temperature at the well 

head was 224°F. 

3. There appeared to be no significant effect 

on adjacent wells when pumping without 

injection. 

4. There appeared to be a measurable effect 

on adjacent shallow wells with pumping and 

injecting into a shallow well. 

5. Flow of the production well was limited 

due to caving and filling of the well 

below the casing (estimated at 82 feet), 

which was determined after the test.

PART II 

HEAT LOADS, WELLS. HEAT EXCHANGERS, 

AND PUMPS 

Heat Load Detennination 

Commercial District Heat Load. Since it is impractical 

to do detailed heat loss calculations on 

each of the downtown buildings, a typical block was 

chosen and the total downtown area heat loss projected 

from the values obtained. 

The typical block was selected to contain a 

mix of building construction with particular attention 

to materials, number of floors in the buildings, 

display windows, and type of business. The 

block chosen is bounded by North 7th, North 8th. 

Main, and Pine Streets. Building construction is 

primarily masonry (brick) with built up roofs and a 

good mix of ceiling heights, some of the establishments 

having been remodeled with lowered ceilings. 

Businesses include an insurance office, two jewelry 

stores, two clothing stores (1 men's, 1 women's), 

an office supply store, two home furnishing stores, 

a photographer's studio, a restaurant, and an outdoor 

sporting goods store with office space on the 

second floor. 

The heat loss of each establishment was calculated 

using ASHRAE recommended procedures and design 

temperature for the Klamath Falls area. Actual 

values used were: inside temperature of 60°F 

(with 10°F night setback during the coldest nighttime 

periods); and design temperature of 0°F, 

which will include 99% of the time. Each establishment 

was inspected, measured, and construction 

estimated and/or obtained from the building occupants. 

Heat losses were estimated based on ASHRAE 

values for the materials and construction involved, 

with wind speed of less that 7 raph. 

Meteorological data was obtained from the U.S. 

Weather Bureau downtown station for January, 1978, 

and the degree days for the month calculated. Heat 

losses for the buildings were again calculated 

using the January weather data and estimated fuel 

consumption was compared with actual fuel consumption 

obtained from building occupants' January 

fuel bills. Calculated values were H.9% higher 

than actual fuel consumption. 

From the information thus obtained, a heat 

load constant of 4.34 BTU/H/ft^ based on building 

volume was estimated and applied to building volumes 

obtained from the City Planning Department. 

Fuel consumption and process heat loads were 

obtained from special case establishments in the 

proposed district. Domestic hot water was estimated 

at ^0% of the district heat requirements. 

These loads were added to the loads calculated on 

the basis of building volume to obtain the total 

heat load. 

Future expansion was provided for by adding 

approximately 12% to the building volume heat load 

estimates but no additional high process loads 

were estimated since zoning restrictions prohibit 

385 

Lund, et. al. 

such future expansion in the area covered by this 

district. 

Total estimated heat load for the downtown 

district is 135 x 10^ BTU/hr and will require 

6,750 gpm of 200°F water with a 40°F temperature 

drop. 

The heat loads for 10 of the 14 buildings included 

in the initial district had been estimated 

using ASHRAE methods for the 1977 county feasibility 

study. Actual consumption of fuel was compared 

against estimated consumption for a period of 

5 years for that study. Estimated consumption was 

approximately 8% higher than actual consumption. 

The heat load values obtained from the 1977 

study were within 15,000 BTU/hr of the values obtained 

when using the constant of 4.34 BTU/hr/ft^, 

The heat load for the Phase 1-14 government buildings 

based on the constant is 15,3 x 10^ BTU/hr, 

Selection of 40 Temperature Drop, Ten of the 

14 initial buil dings presently have hot water heat- 

ing systems at average temperatures ranging from 

144°F to igO^F, One building is partially heated 

by heat pumps s upplied with 100°F water and par- 

tially by 190°F water in finned tube convectors. 

An electrically heated building obviously will re- 

quire a retrofi t to convert to hot water by placing 

water coils in the duct plenums. 

The county jail has a very old steam system 

that is inadequate now, but the existing finned 

tube radiation can be utilized with additional 

lengths of radiation. Modifications must be made 

to enlarge the steam condensate return lines. 

The Veterans Memorial Building, also steam, 

has combination radiation and forced air heating. 

The building has been remodeled and office size 

reduced several times with installation of new radiation 

so that there is excess radiation capacity 

at steam temperatures. Use of 180°F average water 

temperature will reduce the radiation capacity but 

this loss can be offset by increasing th^ coil capacity 

in the central forced air unit. 

The hot water heated buildings, in general, 

presently have average temperature in the 180°F to 

190°F range. Reduction of the average temperature 

to 180°F will reduce the heating capacity by about 

10%. Since the buildings are old and were originally 

designed with over capacity, the present 

systems will require little retrofit except in the 

mechanical room valving and control systems and 

addition of appropriate valves and controls to accept 

water from the district supply system. 

Use of average v/ater temperatures much below 

180°F would require the addition of radiation, fan 

coils, etc., as appropriate. For instance, use of 

170''F average water temperature would reduce the 

heating capacity by about 23% on the average. This 

reduction would be excessive in most of the 

buildings.

W.:-- 

Lund, et. al. 

Since the heat loss of the insulated pipeline 

is less than 1°F at full capacity. 200°F heat exchanger 

outlet, and 160°F inlet temperatures will 

provide very nearly the 180°F average temperature 

considered desirable. 

Wel1s. It is anticipated that two production 

wells and at least one injection well will be required 

for the initial 14 building district. The 

production wells will be near the well on Old Fort 

Road which was tested in July, 1978. The existing 

well at the museum, just a few feet from the heat 

exchanger building site, will be used as the injection 

well. 

Production Wells. There are several geothermal 

wells within a 1,000-ft radius of the proposed 

production well sites but all are much shallower 

and have downhole heat exchangers (DHEs) installed 

so no water production data is available. At the 

time the test well was drilled in 1961, its production 

was estimated to be 500 gpm or more, but no 

pump test was made since it too was intended for 

DHE operation. Since the proposed production well 

sites are within a few hundred feet of the test 

well, the strata and production rates are expected 

to be similar. Local well drillers estimate that 

an average 1,000-ft well in that area v/ould produce 

500 gpn or more and that an excellent v/ell might 

produce as much as 700 to 800 gpm. 

In order to utilize the expected 500 gpm, 8inch 

diameter pumps will be required which in turn 

requires 10-inch minimum diameter casing at the 

purap level. Six-inch diameter pumps (with 8-inch 

diameter casing) could each provide half of the 

756 gpm required for the initial 14 buildings, but 

since the system is intended to be expanded, it is 

advisable to case the wells to allow for maximum 

production. This will also allow the use of only 

one well and pump the majority of the time, and 

greater efficiency in the use of electrical pumping 

power. 

Assuming strata similar to the tested well will 

be encountered, the proposed casing program is for 

10-inch casing to be set to where hard rock is encountered 

at 350 to 400 feet and to continue with 

8-inch to total depth of 800 to 1,000 feet. There 

is a possibility that the producing aquifer will be 

competent and casing not required, but it is more 

Likely that full-depth casing will be required, 

perforated at the producing levels. 

Air or water rotary drilling is the preferred 

method, thus eliminating the possibility of drilling 

mud entering the formation, caking, and requiring 

extensive cleaning operations in order to 

attain full production. This differs somewhat 

from the better known geothermal drilling methods 

where the mud is required to maintain pressures. 

In those conditions, the downhole pressures prevent 

mud from entering the formation and the downhole 

pressure will remove mud when the well is 

first produced. Where the static level is well below 

the land surface, mud can be forced a considerable 

distance into the formation, may cake 

there and require extensive cleaning to attain 

386 

full production. Where formation pressures do not 

force fluid to the surface, the weight of the mud 

is not required to control the hole. 

It must be emphasized that drilling and testing 

of the production wells is of prime importance, 

and should be completed as quickly as possible. 

The design of the entire system depends on the actual 

temperature and flow production characteristics 

of the wells and must be considered preliminary 

until these parameters are known. Pumps, 

pipeline, heat exchangers, temperature drops, retrofits, 

etc., can be designed (with attendant 

cost changes) to provide the required heat with 

fairly large changes from the well characteristics 

assumed—but they must be known to provide the 

basis for the final design. The axiom used in lowtemperature 

direct applications of "never design 

the system till the temperature and flow available 

are known" is very true and a good one to follow. 

Injection Hell. Injection of "used" geothermal 

water is necessary both from an environmental 

as v/ell as political point of view. Environmentally, 

depletion of the reservoir as well as surface 

thermal pollution are the major considerations. 

Chemical pollution does not appear to be a serious 

concern due to the low dissolved solid content 

(800 ppm) and non-toxic ions (mainly sulfates and 

carbonates). Political considerations stem mainly 

from effect on individual residential wells. Temperatures 

of wells in the urban area generally increase 

during the winter use period, due probably 

to less mixing in the reservoir, thus less cooling. 

Seasonal level changes have also been noted. Water 

level changes can be tolerated to a degree in 

wells with downhole heat exchangers (say 10-20 ft), 

however, owners may object to any noticeable changes 

(especially lowering). Visual impressions of 

"waste water and steam" are also of concern to area 

residents. State regulations do not presently require 

injection, however, their passage may occur 

shortly, thus they must be anticipated. 

The location of inject ion wells is a diffi- 

cult task in the urban area as the local geology 

and hydrology is not comple tely understood. The 

effect of injecting in nong eothermal areas versus 

known geothermal well areas is also not understood, 

Several cases of injection are reported earlier in 

this report, however, these have not been studied 

in detail. No noticeable e ffects due to injection 

have been reported in these cases. 

The two greatest concerns of this project are 

to minimize the effect of production and injection 

on adjacent wells in terms of level and temperature. 

Injecting near production wells may preserve 

the level of the reservoir, but lower the temperature. 

Injecting away from production wells will 

eliminate the temperature effects, but will probably 

not assist in maintaining the reservoir level 

near the production zone. 

Three locations for injection wells have been 

considered: 

1. near the production zone on Old Fort Road;

2. near the County MuseLmi well (pr using the 

actual, well); and 

3. near the-end of the secondary supply Tine 

{near the' County Courthouse')'. 

Location 1 is best to minimize the effect on 

adjacent wells in terms of water levels,, but may 

cause premature temperature breakthrough. Location 

2 elimi nates a return pipeTine to the production 

zone and can use the existing museum well. 

Temperature .effect would also be less due to lower 

well water temperatures'in the injection area 

(around 180° to l:9d°F). Location 3 could be considered 

if .the primary heat, exchange facility were 

eliminated, thus elirainatirig the heed for the 

cTosed-lobp sjecondary p.ipellne. Geothermal water 

would theri be desliyered directly to all buildings, 

similar-to the Icelandic system. Each building 

would then be required 'to supply their ortn heat exchanger 

or use the fluid directly. Injection near 

the end of the line would eliminate the need for a 

return linei but may effect cold (60°' to 90°F) water 

wells in the area,. 

LBL reGonmends the^ second location, which is 

the main dfe considered in this report. The drilling 

and testing of at least two deep wells ih the 

production area is necessary to better jevaluate 

this Tecommendatian. 

Dri'ltinq Costs - Klamath Basin. Well drilling 

costs in the Klaraath Basin by cable or r-otary rigs 

up to 3,000 feet are as follov/s: 

$1,00 per inch of diameter-per foot of depth 

in "soft" rock, and 

$2.50 per inch of diamelier per foot of depth 

iri "hard" rock up to 500 feet in defith. 

For every additional 100-foot increment, add 

41.00 per-foot of clepth- 

Casing costs can be estimated at $1 ...05 per 

inch of diameter per foot Of depth. Full^ 

depth casing is assuraed for all wells. 

Using these costs, which include mobilization 

arid dempbilization, and assuraing that the production 

wells encounter the tsa'nie amounts of "hard" and 

"soft" drilling that the test well log indicatesi 

drilTihg and casing of a 1,OdO-ft well would cost 

.$38,,'898 with full-depth casing. These costs are 

expected to: rise apprpximately 10% in the very nearfuture, 

and do not include costs for drilling mud, 

additional air- compressprs if requiredi -foaraing 

ageri'ts, etc. 

Central Heat Exchangers 

there are three basic'methods of transferring 

the heat fro.m the gepthermal water to the buildirig 

•air space. These are: 1} Use-, the geothermal water 

directly iri the building heat emitters.; 2} Utilize 

individual building hea't exchangers to transfer 

heat-frora the geothermal water to a building cTo'sedwater 

loop which in turn transfers heat to the heat 

emitters; arid 3) Utilize large central heat exchanger's 

to transfer heat to a di;strict. closed-war 

ter loop and supply the buildings with fresh-heated 

387 

Lund, et. al. 

water to be used in the heat emitters. Each system 

has its advantages and disadvantages. 

Even though the geothermal water in Klamath 

Falls IS relativeiy pure, the dire.ct use in heat 

emitters Is nol; recommended, especially in the fan 

coil units of air handling systeras and small tube 

baseboard units-. Experience with direct use at 

OIT, Shadow Hills Apartments, Kingswood .Manor 

apartmehts, arid several businesses in the East Main 

Street .area indicate that life expectancy of the 

fan coils may range from 1 1/2 Or 2 years to 12 or 

15 years. At both Shadow Hills and Kingswood Manor, 

leaks in fan coil units developed in 2.years or 

less. Inspection of the units shows corrosion occurring 

in the units priraariiy at soldered joints 

and: changes in direction of the tubes at "the ends,, 

although a few leaks have occurred in the main 

body of units v/here tubes are straight. AtOJT, 

five failures have occurred ir the 14 years the 

Ltriits have been in service., again with most near 

soldered joints, headers^ and at the ends df cOils, 

There are no known di.rect uses of sraalT-finned tube 

baseboaird units, bui: since the materials and methods 

of construction are similar, it is assumed 

they would have Simflar life tiraes. The exact nature 

and cause of the failures, arid as, importantly 

the difference in life of some units, is not. known 

but is undeif study by OIT, Battel Te N-W. and 

Radian Corporation iri a joint effort. Until the 

cause of the failures .can be determined and/br .corrected, 

direct use is not considered practical. 

The-usual material's of construction of fan 

coils are copper "tubes with pressed aluminum fins. 

Other jriatenals which may have' To'nger life are 

avai'lable, but reduce the heat transfer efficiency 

and are more costly. As far as is kriown, all units 

presently installed in any of the air handling 

units in the buildings to be heated in the district 

do have copper tubes. 

Direct Use. The advantages Of direct use are 

that water would.be supplied to the buildings at 

higher temperatuice since heat would not be' lost in 

a heat exchanger and the distriet construction 

cost y/ould be much less'. The main disacfvantage' is 

that iperhaps few customers vôul'd hook up since the 

reduced, cost of heat energy would be offset, or 

p'er haps exceeded by, increased costs of maintenance. 

Since experience is liraited, the cause of 

failures is unknown, arid useful lives of components 

apparently varies considerably even, within individual 

systeras; maintenanGe and, replacement costs 

ate next to impossible to evaluate., and an economic 

comparison be'tween this- system and other's is 

impossible,. 

Indi vi dual Bui Tdinq Exchangers. The second 

riethod, that of .supplying geothermal water to each 

building where heat isr transferred -to a closed loop 

within the .building, is a viable^ alternative and 

offers several advantages but in th'e.overa-TT-, is 

more mostly due to the economics of size. 

Each :building would have its small heat exchanger,, 

probably a plate type, with the associated 

valves and controls to control the pressure flow.

Lund, et. al, 

and temperature in the small heat exchanger and a, 

punitp to return water to the geothermal return line. 

The normal temperature, flow, and pressure controls 

wouTd also be required in the building closed-loop 

system including a water treatment system if so 

desired. 

The individual heat exchange system does not 

require insulated return Tines since all energy to 

be extracted is-taken at the use site, and the^ control 

system is somewhat simplified since pressure,., 

temperature, arid flow'baTance across heat exchangers 

are the responsibility of the building operators. 

Where the geothermal collection :or return is 

a very simple systera, such as direct discharge to 

storm drainage systems or where the collection system 

is much shorter than the, supply systera, this 

method is, probably the most desirable "type. Where 

the collection or return sy.stem is: essentially the 

same as the supply system, i,e., disposal is at ope 

end of,the systera, pipe sizes and puriiping requirements 

will be the same for'-both supply and return 

except,where elevation head provides advantages. 

Advantages: 

1. Initial and operation and maintenance 

costs of tffe district system are less. 

;a. No heat central exchangers. 

b. Simple .control system. 

c, Unins.ulated return lines. 

'2.-. Buildirig operators have the option Of 

.direct use or heat exch'ahge.. 

Disadvantages: 

1. Overal.l initi'al and operation .arid 

mairitenance costs are increased but a 

larger p.ortion is shared by energy 

users:. 

Central Heat Exchangers. The third type. Centralized 

heat exchangers, is similar -ta the initial 

projiosal". (Klamath County Geo-Heating District 

Feasibility Study, 1975.) Actually, the initial 

proposal was som'ewhat'Of a combination of'individual 

and centralized "heat exchangers since two buildings, 

the museum.and fire, sta tion were on their own exchanger;, 

the tv/o; Ci.ty buildings were on another exchanger, 

and the County complex of six buildings 

on a third; exchanger. This type of "mini district." 

system is viable where giôups of buildings are under 

control of a single entity, i.e., the* City,, 

County, oV'perhaps ,a, shopping center. Where many 

buildings are under separate control, the cooperation 

required for the initial installation expenses 

pro rata seeras unlikely. The centralized systera is 

more expensive for the district, but since higher 

quality ene'rciy is delivered to the custotner 

(cleaner hot water), charges for the energy can be 

increased to offset the costs. 

Advantages: 

1^ Lower initial and operation arid maintenance 

costs: to customers which increases 

the desirability of hookup. 

2, Lower total cost;v/hen both district 

and customer costs are considered. 

388 

Disadvantages: 

1. Higher initial and operation and 

mai'ntenance costs to district. 

a. Insulated return lines. 

b. More complex controls. 

For this district heating system, the central 

heat exchanger, method was selected for the following 

reasons': 

1. Direct use is riot desirable due to 

corrosion. 

2. Use' of the existing storm sewer system 

for disposal is impossible-. 

3. At the- present time, disposal appears- to 

be required at one erid of the system. 

4. Customer hookup in.the districts is to 

be encouraged as the system is expanded. 

5. Overall costs (district plus customer} 

are lower. 

6. High-temperature resource is available, 

so temperature loss across the; exchangers 

is not critical. 

Heat Exchanger Type. There are two types of 

heat exchangers that have proven most satisfactory 

in geothermal service: 1) tube and shell-straight 

through with ,geothermal i.n the tube side, arid 

2) plate type. 

Tube and shell exchangers were never seriously 

considered for this application. It is well known 

that iri appli cati on.s where tube materials other 

than steel are required,, and where close approach 

temperatures are required, tube and shell exchangers 

are much' tirofe costly. Other major disadvantages 

are. lack of flexibility to acconimodate 

changes in temperature- and flow conditions= to meet 

load changes, i.e., additional builfdings, drfficult 

and time consuming cleaning when required,greatef 

floor space required, and they are lessefficient. 

For coraparison purposes, specifications g,f a 

tube and shell exchanger for application in the 

ini1:iaT 14-building design v;as obtained frpma 

tube and shell exchanger manufacturer^. 

Geothernal water-tube side - 336 gpra 

219PF inlet 174'°F outlet 

Secondary water-shell side - 378 gpm 

leCF inlet 200°F outlet 

Tube length - 38 ft (would be supplied as 

2 units. 19 ft each) 

Tube diameter - 5/8 in 

Tube material - cupro nickel 

Shell diameter - 18 in 

Overall length - .apprpximately 23 ft 

Price - $36,300 ea'- - 2 required 

The plate type exchanger is generally considered 

superior in applications for liquid-to-liquid 

heat transfer v/here close approach temperatures are 

desirable and materials other than mild steel are 

required. They require little floor space, are 

.easily cleaned, and-are much irore "efficient. Of 

particular importance in this application is the

case of chariging exchanger-surface area to accommodate 

changes in flow and temperature conditions by 

adding or removing plates. 

For instance in this application, as individual 

buildings eome on line, plates could be 

added. Since the plates are in parallel, flow is 

increased while pressure drops reraain the same and 

inlet and outlet temperatures reraain the same. 

Small changes in/seeondary loop inlet temperature 

(or priraary for that.matter.) can-be accommodated by 

adding or reim.ving plates and still maintairi outlet'temperature. 

Where-large secondary inlet water 

temperature changes are raaae (for instance, if 

all buildings changed from a 40°F T to 6d°F T) it 

may be necessary to series portions of the exr 

ehanger. This can be accomplished with external 

pluratiing while using the same exchanger plates arid 

adding, a blocking plate between the" seried sections. 

Design Recommendations. For the initial 14building 

district 2 plate-type heat, exchangers are 

arranged in parallel with automatic controls to 

stage the flow in both the pumps and exchangers. 

Thus, loads' up to 50i of peak will be handled by 

one pump and exchanger,, reducing pum"pihg costs and 

provi di rig maintenance time. One unit, will prpvide' 

the heat required approximately 65% of the' time 

during the Klamath Fa-lls heating_ season. 

The exchangers will be selected to operate at 

the mini [iiura flows required fpr domes tic, water heating 

during surmer months arid also allow the, addition 

of plate's to handle inc'reased loads while 

maintaining inlet-and ,outlet temperatures as the 

district is expanded. 

plate heat exchanger general s'pecif icati ons: 

Type - Single pass with 150 

• 316, sst plates EPDM gaskets 

Size - 9'3" long x 1'7" y/ide x 5' high 

makirtium platage 

Geothermal side - 219°F Tnlet 

175°F Outlet 

4.3 psig pressure drop 

(1,000 gpm maximum 

flow with full 

platage.) 

350: gprii flow 

Secondary "side - eOQ^F Outlet 

160°F Inlet 

3.7 ps.ig pressure ;idrop 

(1,000 gpra raaximum 

flbw.wi'th full 

piatage) 

376 gf)m flow 

Cost - .$14,000 ea. - 2'required 

Life of the '316 sst plates is expected to be 30 

years qr more in the Klamath Falls geothermal waters... 

Gasket life, is expec.ted to ,be 5 years v/ith' 

frequent cleaning, and gasket cost is $41 each- 

The unit tan be disassembled for .cleaning and reassembled 

in 4 hours by 2 riieri. Additional plates 

for future expansion cost, $80 each including, gaskets." 

Estimated maintenaricl costs—5 years-- 

$6,340. 

389 

Pumps 

Lund, et. al. 

Production Well -Puraps. The productipn well 

pujiips are vertical turbine v/ith variable speed 

fluid drive. The variable ispeed drive provides 

for coritinuous. operation of the pumps to provi die 

constant pressureat the well head and in the supply 

iirie urider varying flow requireraents. Pump 

discharge pressure is monitored by the fluid coup- 

Itng control which changes turbine shaft speed to 

mairitain constant discharge pressure Troin rio-flow 

to full-flow conditions and eTiiiii nates the need 

for stoi'age tanks required with iritermittent,pump' 

operation. The turbine shaft is always rotating 

proyiding lubrication for reduced bearing and. 

shaft wear, the drives have proven successful in 

the Oregon rrfstitute of Technology and Presbyterian 

Intercommunity Hospital systeras; v/here it is estimated 

that bearing, sKaft, and raotor li-fie have-been 

doubled. 

-Vertical turbine-pumps are selected by choosing 

the most economical combination of pulrif bov/1 

arid nuraber of stages that will produce the.desired 

pressure and flow rates,. Attention must be giveri 

to efficiency arid'where variable speeds are a rêquiferaent, 

the pump curve should be ,as flat as possible 

to maintain high overall wire-to-water 

efficiency. 

Well Head Pumps. 

Vertical turbine witli variable . ;peed drive: 

.Rated flow at 1750 RPM 

500 gpm 

Column length 

350 ft 

Golumn diameter 

Sowl diameter 

8 in 

9 3/4. iri 

Shaft diameter. 

1 1/2 in 

Number of bov/ls 

11 

Discharge' p'ressure 

20 psi 

Motor (electric) 

Drive - torque, converter type 

2i,slip at full load. 

75 hp 

Rated Capacity 

75 hp 

Wire-to-water efficiency 

Current cost 

72% 

$41 ,-488 

'Number requi red . 

Estiraated maintenance costs;: 

2 ea 

Change packing .S-lubricate, 6- mo. 

interval 

Pull pump', inspect S replace 

$29 

bearirigs, 3-year iritervals 

Overhaul variable speed drive, 

$4,000 

5-year interval 

$580 

Ih.i'ection Pump. Since the museum well has 

been selected as the injection site, and since the. 

well is; a flowing artesian v/ell,, an inj.ection pump 

will be required. It is assumed that injection 

pressures foir a goOd producing well, are .approxiriately 

equal to the drawdown pressures plus any artesian-pressure 

when that well is used for injection. 

This has been experienced at Raft River arid 

in Klaraath Falls. Additional pumping pressure of 

ab_qut ;25% is recommended to account for the difference 

in temperature when irijectiori temperatures are 

Ipwer than pr'oduction temperatures, gradual fouling

Lund. et. al. 

of the well with continued us.e.,: and, to account for 

any injection of debris, scaling, ^tb. 

The drawdown curve of the museum well indicates 

a drawdown of'50 ft at 800 gpm production. The well 

normally has a'2-foot to 4-foot artesian head. Injection 

pressure then should be approximately 54 ft 

plus 13.5-ft allowarice fof^ fouling for.67.5-ft 

total or 29;3 psi. 

For injection, a horizontal centrifugal pump 

was selected. The pump curve is flat at these low 

pressures. The most economical Itretriod of maintaining 

NPSH under varyirig suction flow conditions is 

to divert a portion of the discharge back to the 

inlet to maintain HPSH well above the cavitation 

pressure, rather than a variable 5pe.ed drive. 

injection pump: 

Horizontal centrifugal 

Rated output @ 1750 RPM, 800 gpm @ 35 psi 

Inlet diameter- 

Outlet diaraeter 

Impeller trimmed to 

NPSH 

Motor (electric) 

Wi re-tp-water effi ciency 

Including, bypass piping and 

controls', base, and guards 

Current price 

Estimated maintenance costs: 

Change packing & lubricate, 

• 6-mo. interval 

Inspect pump and replace 

bearings, 5-year interval 

5 in 

6 in 

9 13/16 in- 

8 ft 

20 hp 

71% 

$2,587 

$20 

$275 

PART III 

DISTRI8UTI0N PIPING NETWORK AND CONTROLS 

The Network 

The desigri of the district heating piping network 

is of vital importance to the economics of the 

system,. There is a trade-off between economics and 

reliability depending upon the pipe material, insulation, 

and p.laceraent raetho.d selected. It is important 

for- this piping network to be ar'ranged according 

to a predetermined plan, where basic conditions,, 

such as heat demands, productipn field identification, 

and siting of wells are' decided at an 

early stage. 

Two types of .piping sys.teras are required in 

the Phase I design; ari insulated primary pipe to 

supply the central heat exchanger from the wells; 

arid insulated supply and return pipes providing 

heat to the buildings from the central heat'exchanger 

(see Figure 4). Bpth systems will be, located 

in developed residential arid cdiijiier^cial areas, 

requiring underground distribution. 

The secondary pipeline is desigri'ed to initially 

supply heat to the 14 government buiIdirigs 

(Phase I), however, it is also sized (8 in} to supply 

adjacent commercial buildings, on 11 city 

blocks (Phase II). The primary pipe is sized to 

supply Phases I and II, however, it will be housed 

in a" concrete duct that will have space available 

to irista'll a future pipe that will handle Phase III 

of the project. 

LECEMO 

- SiHGLE COhTTaDLLCO Cl£PW.,JOiHT 

:: CONtflETE TUflHEt. 

FIGURE 4". Distribution Network 

390 

LLC CE£.-IH£in*h- CX)«S;._-*HT5 

-C0HC8ETE Tl^W^- 

ElII^KSOil JOr.NT i 

^CHOR OtTAlL 

Cl-R Of KLÛATH F*u^^ ., ^HCGOK 

t

The' following four^ types of piping systems 

were investigated: 

- Steel Pipe in a Concrete Tunnel (350°F Maxiraura 

Temperature). This type systera is essentially 

a poured-iri-place or precast reinforced concrete 

tunnel with removable'concrete lids, which ca'h be 

used for sidewalks, and renraved to provide access 

for maintenance or insiiallation of future p.ipeS;. 

The insulated carrier pipes'are supported on steel 

rollers which are imbedded into the concrete tunnel, 

hfter installation, piges are insulated with 

preformed fiberglass or rPckwool. Allowance for 

expansion is by\a bellows type expansion .joint 

which is dual acting with an anchor.between the bel- 

1 ows. The pipe is al so free to expand at elbows 

with the use of guides. The concrete tunnel is 

placed on a gravel bed which contains a dizain tile. 

The concrete tunnel is extremely durable, can be 

used for other utilities, arid can be; constructed by 

local contractors. Its main drawbaek is that it is 

expensive to .construct compai-ed to other type systems 

. 

Concrete tunnel type pi pi rig is popular in 

European district'heating systeras and the Icelanders 

who usually use it for pipes larger than 10 inches, 

in diameter, -claim there is no better system. 

CONCBETE TFffiNirf) 

INSULATION 

sreeL PIPE 

ROLLER PW) 

'BACKfiLL 

GBAVEL BED 

FIGURE 5. Steel Pipe in a Concrete Tunnel 

Steel Pipe in a Protective Co.verinn ,(25D°F 

Maximum Temperature).- A single carrier pipe- is enclosed 

in polyurethah irsulation with a. tight jacket 

of glassfiber reinforced piasti'c (FRP) of PVC., 

Joints of pipe are welded, insulated, and sealed 

with a joint kit and placgd in a bed of sand in the 

CLASS 8 BED 

FRP JAGKET 

URETHANE INSULATION 

STEEL RIPE 

FIGURE 6. Steel Pipe in a Protective Covering 

trench. Manholes are constructed between anchor's 

to house the! expansion bel Vows and insulation 

around elbows is oversized to allow expansiori. 

There are usually eight segments (320. ft) between 

an anchor and manhole, the manholes are construetedof 

reinforced concrete; with drain provisions, this 

type system is very durable, rêsistant to external 

corrosion^ however, susceptible to exterior cdrro- 

391 

Lund j et. al. 

sion. Although costs per lineal foot are comparableto 

rion-TCtallic pipe, the added cost for manholes 

arid expansion bellows makes it more expensive. 

Fiberglass Reinforced Plastic Pipe (FRP) 

(.210°F Maximum temperatureT^ A .single: FRP carrier 

pipe is enclosed in polyurethane insulation with a 

tight jacket of FRP or PVC. The pipe is a filament 

wound fiberglass with either epOxy or polyester 

resin plastic. The epoxy type can handle 

temperatures up to 350°F 'a'nd has a low coefficient 

of roughness, C = 140. The pipe, usually does not 

have any expansion joints,, as the co.efficient of 

linear expansion is 8.5 x 10^^ per °F as corapared 

to 12 X., 10"^ per °F I'or steel pipe. Elbow_s are located 

in poured concrete thrust blocks in Order to 

hold the pipe in, position and allpw expansion in 

straight lengths. A polyester resin pipe of this 

type failed recently when it pulled apart, raairily 

,a;t joints, when the pipe cooled. There is available 

pn the market a slip-ring type joint.tha't may 

be more desirable than the epoxy jpiried pipes. A 

check On the filament wound epoxy resin pipe installation, 

carrying .353°F'water", proved satisfactory, 

hov/ever, flashing must never occur in FRP 

pipe. In areas wHerê flashing conditions' are expected, 

steel pipe sections must be used. The main 

'advantages of this type piping systera is its resistance 

to corrosion and Tow roughness coefficient. 

BACKFILL 

FIGURE 7\ Insulated FRP Pipe 

CLASS B BE13 

PVC JACKET 

URETKANE INSULATION 

FRP PIPE 

Asbestos Cement Pipe (AC) (200°F Maximum 

Teraperature). This type.pipe has ân epcfxy 'lined 

AC 'carrier' pipe, polyurethane insulation arid an AC 

•^^^

Lund, et, al. 

special heat resistant slip-rings for the 1,6-in 

supp,ly line In the; winter when the ;demand is large 

and velocities are high and a second S-inch line 

in the summer months when the load was low. AC 

pipe raay fracturie when a temperature change (codling) 

occurs. Expansion occurs in the slip-ring 

type joints and proper bedding and backfill are important. 

The main advantage of AC pipe, is its resistance.to 

corrosion, however. Its cost per lineal 

foot (16 in) is-the largest of any of the four systems 

inyestiga,t.e.d. Ihe sii paring joints are, quick 

to assemble need for expensive expansion joints and 

manholes. 

Piping Recommendation 

The distribution network is the most expensive 

part of the district heating scheme, therefore, it 

is very iraportant to build it in the very best way 

possible. 

Steel pipe, in a' concrete duct was selected 

for the 4&60-ft primary supply pipe: carrying 220°F 

geothermai water: The main advantages of this 

type systera are; 

1. access to the pipe for future taps. 

Z. access for maintenance arid têpair. 

3. other utilities may be readily installed 

iriitially or at a future date in the 

sarae trench, 

4, better a'ssurarice that ground water will 

not come in contact with the pipe. 

5. the Vid may be used for a sidewalk, wi;fh 

heat radialirig from the p'ipe providing 

snow removal, 

6, the duct fray be oversize'd so that pipe's 

in the future riay be added as the district 

heating system gfpws'. This is. especially 

true in the-case of the main 

.^supply line. 

'Disadvantages of the concrete duct system are: 

^. it must be v/atertight to the highest extent,possible,' 

because its raain task is 

to protect the steel pipes against external 

water. 

2. high,demand for reiriforcenient of concrete 

tat traffic crossings. 

3. in the case of a high ground water level, 

there is a risk that the duct will rise, 

4. costs are high corap.ared to the other 

:syste'ms. 

Direct-buried FRP pipe was selected for the 

secdri'dafy closed loop, because of the lower supply 

temperature (180''F) and it is anticijiated there 

will not be a need for future pipe installations 

along its route. This type pipe has advantages of 

having a low-friction factor, corrosion resistanc'e. 

and does not require special equipment for expansion 

'allowances.. 

Concerning the choice of a. piping system, it 

must be 'empHasized that regardless of which of the 

systems chosen, the quality of construction and execution 

of the work are of'the utmost importance for 

the supply in a long lifetime. 

392 

Controls 

The-quantities which raust be coritrolled in the 

district heating network; are primarily the fluid 

flow rate frora the productiori wel.ls to the centralized 

heat exchanger station and flow rate and temperature 

iri the closed secondary loop supply to 

subscribers. 

The flow in the pri"many geothermal fluid supply 

line is regulated by pneumatic butterfly valves' 

(V-1 arid V-2) located on the reject side of the 

heat exchangers which are controlled by outside air 

temperature (Tl) temperature '(T2) via Receiver- 

Control ler J1. (F i g ure 9.). Clos i ng 0 f control val ves 

V-1 and/or V-2 results in increased pressure iri the 

primary supply line which in. turn is relayed to a 

pressure control regulator located at the production 

pump, reducing the pumping rate oi" the variable 

speed/fluid drive deep well vertical turbine pumps 

(TPl arid TP2). A reduction iri pressure due to 

opening of valves resulting frora a drop in outside 

air teraperature (T]) and geothermal return fluid 

temperature (T^) causes the pressure controller to 

increase the pumping rate. 

The flow in the se,cpndary closed loop is regulated 

by the teraperature and pressure difference 

between the supply and return iines. The most, remote 

point in the system, at the County Courthouse 

coraplex, will be the critical location. In order 

to. proyide sufficient heat to subscrib'ers, the pipe 

temperature, loss to this point will be kept to a 

minimum of .3°F and the pressure to a minimum df 

60 psi. 

The supply teraperature in the .closed s'econdary 

loop is cdntrbiled on .the basis of measured out- 

.side ;air temperature (Tj) and heating, water "return 

temperature (T3), Receiver-CPntroTler #2 will activate 

pneumatic g.lobe valves V-3 and/or V-4 to 

open when outside, air temperature (T^) and heating 

water return temperature (T3) drop. The result is 

a, reductiori of pressure' in the 'heating water supply 

(Pi) and return (P2) line, causing an increased 

pumping, rate, of the variable speed/fluid drive vertical 

turbine circulation pumps (CPl and GP2J. 

Receiver-Contfoiler §3 regulates the pressure 

in the'closed-loop network through the balancing 

globe valve V-5 when sensing supply pressure" (Pj) 

arid return pressure (P2.). This assures that design 

pressures are maintained to subscribers. 

Failures in pumps of pipelines and unusual 

flow rates, temperatures, or pressures, will be 

monitored by a master flow cohtroller (MCl). This 

includes "the pressures in the pipeline as v/ell as 

the" expansion tank., The raaster flow controller, 

under these circumstances, will shut dpwn the 

pumps i'n either pipe system arid sound ari alarm iri 

the heat exchanger/control building. This alarm 

will be monitored in the Fire Statiori. 

Examples'of possible critical situations would 

be a "fully open" indication from a control valve 

under low heat load conditions; a reduction in 

pipeline pressure under high pumping rates (due to

.PUMP 

CONTDOl. 

CEOTHERMAL Pnoa MJECTION WELL 

WELLS 

a rupture); or a drop in supply temperature (caused 

by a closed valve or stopped pump). 

When the project is expanded to Phase III, a 

computerized control center will replace all chart 

recorders and provide BTU calculations for remote 

building as well as temperature and pressure of 

heating water supplied and used. 

PART IV 

LIFE CYCLE AND COST ANALYSIS 

For the Klamath Falls district, heating of 

the central business core Phase.II (the elevenblock 

district) was evaluated due to the fact that 

this phase will be completed in the very near 

future. 

Cost benefit analysis was based on the annual 

heat load using geothermal energy.as opposed to natural 

gas. The economic analysis was based on the 

following assumptions: 

1) The economic inflation rate was forecast 

at 7%. As of this writing, 9% would be more 

accurate. 

2) Inflation rates for conventional energy 

were obtained from the Oregon Department of Energy 

as follows: 

a. natural gas--5.2% above the economic inflation 

rate through 1986 and 1.5% above 

the economic inflation rate thereafter. 

b. electric power—2.5% above the economic 

inflation rate through 1986 and 1.5% above 

the economic inflation rate thereafter. 

T 

r~ 

1 

flC-» 

r--- 

SXI}J-SH 

i VJ* 

• 11 

J J 

r^ ' ^ 

- . o . — 

FIGURE 9. Distribution Network Control 

393 

pRCSsunrzeo 

T*#«r 

MEAT EKCHAMGEH/COWTROL BUILOtwC 

Lund, et. al. 

3) Cost of capital 6.5% as indicated by the 

City of Klamath Falls. 

4) Current cost of natural gas $0.34394 per 

therm (rate paid in February, 1979). 

5) 85% efficiency for natural gas. 

These inflation rates have proven to be very conservative. 

During the past 3 years, the City has 

experienced a 26.5% per year increase in the cost 

of natural gas as compared to 12.2% in our evaluation. 

The fact that actual inflation rates exceed 

those used in the study further supports the arguraent 

for the geothermal system. 

Tables I and II of the report show capital investment 

for 16 combinations of primary and secondary 

piping systems. 

Life cycle costs were calculated on these 

piping systems for a 10-year period and appear in 

Tables III and IV. 

A fifty-year life cycle cost analysis was completed 

on four piping systems and the results are 

illustrated graphically on the chart following. 

Although steel pipe installed in concrete tunnels 

requires the highest capital investment, the 

annual maintenance costs were estimated to be considerably 

lower. Such a system provides easy access, 

room for future expansion at minimal cost, 

and reduces maintenance time and cost particularly 

in conjested business districts.

Lund, et. al. 

Ste«) 

in {«) 

Tunne\ 

" « ' lb) 

Surlal 

"' (cl 

Burled 

Burtea 

K- StMl 

In Tunnel 

(I) 

726,463 

637,060 

l,363.S!3 

7?6,«63 

490,072 

1,216.535 

726.463 

329,118 

1.055,581 

726.463 

329,12? 

1,055,592 

TABLE I. TABLE III. 

Piping Hft^cw., Cost, 

(In i) 

Prlurr Supply PipeUne 

8- Steel 

In Tunnel 

(in 

506,175 

637,060 

1,143,235 

506,175 

490.072 

996,247 

5(»,)75 

329,118 

835,293 

506.175 

329,129 

835,304 

ft. 

000,000 • prleia ry line COM 

ooo.ooo • secofwlAry line cost 

0,000,000 - Iou1 pipeline cost 

Co,t figure. Used on J«nu«ry 1979 esiimate,. 

steel 

in 

Tunnel 

Steel 

SurieO 

Flip 

Surfed 

AC 

Surled 

(a) 

(6) 

(O 

(0) 

TABLE II, 

Total Project Cost 

Prtwry Supply PipeKne 

16- Steel 

in Tunnel 

(1) 

1,730,301 

1,990,421 

1.583,813 

1.821.385 

1,422.859 

11636.288 

i,422,670 

1,636,300 

8- Steel 

in Tunnel 

(11) 

1,510.513 

1,717,090 

1,363,525 

1,568,054 

1,202,571 

1,382,957 

1,202,582 

1,382,969 

16- StMl 

in Tunnel 

(III) 

471.564 

637,060 

1,108,624 

471.564 

490.072 

961,636 

471.564 

329,116. 

600,682 

471.564 

329,129 

800,693 

16' Steel 

Burled 

(111) 

1,475,902 

1.697,287 

1,328,914 

1,528,251 

1,167.960 

1.343.154 

1,167,971 

1,343,167 

000.000 - Basic cost 

000,000 - I5X engineering I Inflation costs added 

Note: Basic cost • Hell costs (5169,772) , pipe costs 

(Table 7 ) • beat exchanger costs 

(S197,Soe) 

B- Steel 

eurled 

(IV) 

282,154 

637j060 

919,214 

262.154 

490,072 

772.226 

282.154 

329,118 

611,272 

282,154 

329,129 • 

611.283 

8- Steel 

Buried 

(IV) 

1,286,492 

1,479,466 

1,139,504 

1,310,430 

978:550 

1,125,332 

978,561 

1,125,345 

394 

tr 1 

8 

9 

10 

10 »c«« coiT cowwiisa OF pic-wit npnt. vtstcn 

USI»C CAPITAL WCOKi-l AKD "Jl.VItKAdCE tCSTS 

• 16 

y 

243,534 

156,574 

S 23.334 

20.146 

12,955 

i 1,910 

• Steel 

2 

3 

4 

5 

6 

7 

B 

9 

10 

in Turnel 

416,168 

17.299 

18,510 

19,806 

21,193 

22,676 

24.264 

25,962 

27,779 

29,724 

loHl tost 223,388 

Present value 143,621 

Annual Cquiv, 

Cost i 21.404 

5,tee c 

S17.6J6 

yr 1 

18,860 

2 

20,1.10 

3 

21.59! 

4 

23,!04 

5 

24,721 

6 

26,452 

1 

28,304 

30,285 

3.',4!;5 

Tota Cost 

^-esen , Value 

Annual 

tOuiv, Lost 

Tola *, Cost 

Present Value 

Annual 

tDui, . Cost 

ir. Tunnel 

511,265 

12,054 

12.897 

13,800 

14,766 

15,800 

16,906 

19,089 

19,356 

29,711 

155,6C3 

100.069 

5 14,913 

Annual Co,t 01 Bur •:ed Steel Annua' Lost of 16* 

over steel in Tunnel . Siis. 8- Ste.; 

yr i 1,458 

1,560 

yr 1 S 4,901 

5,241^ 

1,670 

3 5,6!3 

1,786 

I.s;.' 

2,045 

2,189 

4 

5 

6 

7 

6.Nt 

6,^26 

6,877 

7,158 

8 2,341 

3 7,873 

9 2,505 

9 8,424 

10 2.680 

10 9.014 

67,7«0 

43,552 

5 6,491 

a- Steel fiuried 

yr 1 510,560 

2 11,320 

3 12,113 

4 12.961 

5 ii.ses 

6 14,839 

7 15,878 

8 16,989 

9 IS,178 

10 19.451 

Total Cost 146,181 

Present Value 93,984 

Annual 

Coul«. cost 5 14,006 

i'«l trVlLif i.,fr §-" Stil! 

Sur ifi) 

yr 1 5 685 

2 733 

3 785 

4 840 

5 898 

6 961 

7 1.028 

8 1,100 

9 1,177 

10 1.260 

Total.Cost 9,467 

Present value 6,085 

Anrtuti 

Equiv, Cost 5 907 

Forecasting life cycle costs over a 50-year 

period leaves much to be desired in regard to accuracy. 

Data on maintenance costs of pipelines for 

50 years is not available due to the lack of experience 

with such piping systems. 

Table VI shows a total cost suramary for the 

project. Table V concludes the study by comparing 

the annual cost of• the geothermal system with 

the annual cost of continuing to use natural gas 

over the next 20 years. Using a 6.5% cost of 

capital, the present value of annual savings exceeds 

$7,000,000 in 20 years. With a capital investment 

of $2,000,000, payback would occur in 

less than 7 years. 

The average annual equivalent cost per therm 

for the 20-year period is $0.29 for geothermal as 

compared to $0.94 for natural gas.

jr 1 

yr 2 

yr 3 

yr 4 

yr 5 

yr 6 

yr 7 

yr 8 

yr 9 

yr 10 

TABLE IV. 

:o YiAii COST can>)»;;so,\ w 5iCG-,>i3v ?ip;ac CTSTin usiss 

CAP-TAi S£COVEPT Mii KAI.^TIKAMCC COSTS 

Stee 

jr 1 

yr 2 

yr 3 

yr 4 

yr 5 

yr 6 

yr 7 

yr 8 

yr 9 

yr 10 

Total Cost 

Present Value 

Annual 

Equiv. Cost 

Buried Steel 

18,318 

19.600 

20,972 

22,440 

24,011 

25,652 

27,490 

29.415 

31.474 

33.677 

5253,093 

162,716 

24,250 

In Tunnel 

—'.^Trii 

15,170 

16,232 

17,369 

18,585 

19,885 

21,277 

22.767 

24,361 

26,066 

5195,894 

125,946 

18.770 

yr I 

yr 2 

yr 3 

yr 4 

1' ,5 

yr 6 

yr .' 

yr s 

,r 5 

yr 10 

Total Cost 

Present Value 

Annual Equiv. 

Cost 

f«P 

18,734 

20,046 

21,449 

22,950 

24,557 

26,276 

28,115 

30,033 

32,189 

34.4«3 

3258,847 

166,417 

24,801 

Annual Cost of Buried Steel Annual Cost of fPP Over 

Over Steel In Tunnel 

Steel in Tunnel 

yr 1 

4,140 

yr 1 4,557 

yr 2 

4.430 

yr 2 4,875 

yr 3 

4,740 

yr 3 5.216 

yr 4 

5,072 

yr 4 5,582 

yr 5 

5,426 

yr 5 5,972 

yr 6 

5,806 

yr 6 6,390 

yr 7 

6,213 

yr 7 6,838 

yr 8 

6,648 

yr 8 7,317 

-,r 9 

7,113 

yr 9 7,829 

ir 10 

7,611 

yr 10 8,377 

t 57,199 Total Cost 

562,953 

36,772 Present Value 

Annual Eouiv, 

40,471 

5,480 Cost 

6.031 

/ear 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

NATURAL GAS 

Present Cost 

242.822,00 

272.446.28 

305.684,73 

342,973.27 

384.821.62 

431,769,85 

484,445,78 

543.543.16 

589.749,75 

639.878,48 

694,268,15 

753,280,95 

817.309,83 

886,781.16 

962,157,56 

1,043,940,95 

1,132,675,94 

1.228,953,39 

1.333,414.43 

1,446,754.66 

1,569,728.80 

Asbestos Cement 

yr I 

yr 2 

yr 3 

yr 4 

yr 5 

yr 6 

yr 7 

yr 8 

yr 9 

yr 10 

Total Cost 

Present value 

Annual Equiv. 

Cost 

-.9,862 

21,252 

22,740 

24,332 

26,035 

27,857 

29,807 

31.894 

34.127 

36,515 

S274.425 

176,434 

26,294 

Annual Cost Df Asbestos 

Cettcnt Over Steel in 

Tunnel 

yr 1 

yr -i 

yr 3 

yr 4 

t' 5 

yr 6 

yr 7 

Vr 8 

yr 9 

yr 10 

Total Cost 

Present Value 

Annual Equiv. 

Cost 

5,684 

6,082 

6,507 

6.963 

7.450 

7,972 

8,530 

9,127 

9,766 

10.450 

578,531 

50,488 

7.524 

TABLE V. 

7S0 

toooMaof 

St«al l» TaHIB« ItMl 

1! 55 3 55 K" 

STSTOl LIFE I« TIMS 

FIGURE 10. 

20 Year tja%x. Comparison of Natural Gas vs. Geothermal For An ll-B1ock Area 

With A Heat LoatJ of 6 x lO^ Therms/Vear 

GEOTHERHAL 

ELECTRICAL 

Present (Ijst 

8,492,00 

9,213,82 

9,996,99 

10.846.74 

11,768.71 

12.769.05 

13,854.42 

15,032,05 

16.321.80 

17,722.21 

19.242,77 

20,893,80 

22.686,49 

24,632.99 

26,746.50 

29,041.35 

31,533,10 

34,238.64 

37,176.32 

40,366.05 

43,829.45 

GEOTHERMAL 

OPERATIOM AND HAIMT. 

Present Cost 

1,090,00 

1,166.30 

1,247,94 

1,335.30 

1,428.77 

1,528,78 

1,635,80 

1,750.30 

1.872.82 

2,003.92 

2,144,19 

2,294.29 

2,454,89 

2,625,73 

2,810.60 

3,007.34 

3.217.86 

3.443.11 

3.684.13 

3,942,02 

4,217.96 

395 

Annual Savings 

262.066.16 

294,439,79 

330,796.23 

371.524,14 

417.472.02 

468,955.56 

526,765.81 

571,555,13 

620,142.35 

672,881.19 

730,092,86 

792.168.45 

859,521,44 

932.600,46 

1.011,892,26 

1,097,924,98 

1,191,271,64 

1.292.553.99 

1,402,446,60 

1,521,681.39 

TOTAL 

15,368.862.44 

Present 1/orth 

6.5X 

246,071.52 

259,595,58 

273,849.36 

288.872.02 

304,704.83 

321.391.24 

338.977,07 

345.351,44 

351,845.44 

358,461.33 

365,201,38 

372,067.94 

379,063.36 

386.190.08 

393.450,55 

400,847,28 

408.382,83 

415,049.80 

423.880.84 

431.848,66 

TOTAL 

7,066,112,54 

Lund, et. al, 

Present Worth 

8t 

242,653.86 

252,434.67 

262,596.71 

273,154.83 

284,124.44 

295,521.55 

307,362.79 

308,793.45 

310,230,57 

311,674,18 

313.124.31 

314,580.99 

316,044.25 

317.514.12 

318.990.64 

320,473.83 

321.963.74 

323,460.38 

324.963.80 

326,474.02 

TOTAL 

6,046,137.14 

/ /

Lund, et al. 

3. 

4. 

References 

TABLE VI. 

TOTAL COST S(JWARY 

Case I la 

(8", 6" Steel Pipeline in Concrete Tunnel) 

A. Wells and Well Head Equipment: 

Jiem Cost 

1. Production well (2) e $38.898 $ 77,796 

2. Production well pumps (2) S $41,988 83!976 

3. Well head buildings (2) P $3,500 7I0OO 

4. Power hook-up in buildings (2) p $500 I.OQQ 

8, Bistribution Piping Network: 

SubtoUl: 169,772 

5, Priraary supply pipeline (8" steel in concrete 

tunnel) 

6. Secondary supply pipeline (8" t, 6" steel in 

concrete tunnel, 3" steel buried 

Heat Exchanger Building: 

Subtotal: 

7, Plate heat exchangers (2) (? $14,000 

8, Control system, wiring, etc, (basic) 

9, Circulation pump (2) 9 $13.691 

10. Expansion/surge tank 

11. Building including installation of equipment. , . 

12, Injection well (museum) , . , . 

13, Injection well purap 

0. Overhead Costs: 

Subtotal: 

506.175 

637.060 

1.143.235 

28.000 

44,537 

27,382 

5,000 

90,000 

2.587 

197,506 

Total Equipment and Installation Costs: $1 ,510,513 

Engineering ? lOX 

Contingency (inflation 9 5i for 6 mos,) 

Culver, G, Gene, John W. Lund, and Larsen S, 

Svanevik, Klamath Falls Hot Water Well Study, 

(UCRL Report 13614), Oregon Institute of Technology, 

Klamath Falls, Oregon, October, 1974, 

Lienau, Paul J., John W. Lund, and G. Gene 

Culver, Klamath County Geo-Heating District-- 

Feasibility Study, Geo-Heat Utilization Center, 

Klamath Falls, Oregon, January, 1977. 

Lienau, Paul J., John W. Lund, G. Gene Culver, 

and Douglas Ford, Klamath Falls Geothermal 

Mini-Heating District Feasibility Study, Geo- 

Heat Utilization Center, Klamath Falls, 

Oregon, October, 1976. 

Lund, John W., et. al., Geothermal Hydrology 

and Geochemistry of Klaraath Falls, Oregon, 

Urban Area, Geo-Heat Utilization Center, 

Klamath Falls, Oregon, July, 1978. 

151.051 

75,526 

Total Cost: $1.737.090 

396 

5. Lund, John W., Paul J. Lienau, G. Gene Culver, 

and Charles V, Higbee, Klamath Falls Geotherraal 

District Heatinq - The Commercial District 

Design. Interim Report, LLC Geothermal 

Consultants, Klamath Falls, Oregon, February, 

1979. 

6. Sammel, E. A., Hydrologic Reconnaissance of 

the Geothermal Area Near Klamath Falls, Oregon, 

Water-Resource Investigation Open-File Report 

WRl 76-127, USGS, Menlo Park, California, 

1976. 

*This paper is the combined effort of four 

speakers.

ABSTRiCT 

Ttte igeology of .ore deposits in c;arbonate' rocks in 

the eastern Great Basin gives );nsight into the 

geology of present day geothermal reservoirs in 

carbonate rocks. The Cove Etirt KGRA is geologically 

similar to the Tintic mining district and 

the geblogy of the Carlin mine area suggests a 

cartxinate reservoir at the Beowawe KGHA. Carbonate 

geothennal reservoir's are unique in that fluids 

moving along fractares may leada calcite and, less 

often, dolcroite and thereto increase poKJsity and 

permeability. 

IMTRQDUCTHa) 

Geologists geherally recognize that most of 

the: ore deposits of the •western U.S. are "fossilize3" 

geothetmal systems. However, while ôme 

detailed attention has teen given to the use of 

the "porphyry copper model" in geothermal explbration, 

little attention has beên given to other 

types of ore deposits found in areas being eicplored 

for geothermal reservoirs. Tlie purpose- of this 

paper is to point out similarities between ore 

deposits arid geoUiermal rfeservoirs in carbonate 

rocks in the eastem Great Basin and to indicate 

some of the unique problems_ and features of carbonate 

geothermal reservoirs. Two major mining 

districts and two *major geothennal prospects are 

discussed telbw. "Hieir bdmparison is made possible 

as a result of data from exploratory geothennal 

wells having been purchased by the Departinent of 

Enetgy ard made available throiqh the University of 

Utah Research Institute (UURI). 

The only"producing carbonate geothermal reservoirs 

at this time are the Lardarello arid Mt. 

Amiata fields in. Italy Vihere production is from 

highly permeable, fractured carbonates^ capped- by 

shaly fiysch facies which have beeti thrust over 

the carbonates (Gelati, et al., 1975). While 

space does not permit a 

silver, copper and gold ores valued at oyer $568 

million at th.e time of ptbductibn (Morris and 

Mogensen, 1978). The ore bodies of, the district 

consist of both massive, irregular replacements 

and replacement -veins ih folded and faulted 

Paleozoic limestones and dolan ites and open space 

fillings in narrower fissure" veins in Paleozoic 

quartzites arid Tertiary igneous rocks. The ore' 

bodies are believed to have been deposited by 

hydrothermal fluids following a period of major 

vblcanism in the East Tintic Mountairis which took, 

place iri the Oligocene, eridlng about 31.5: million 

years ago. Itife vblcanic activity was centered a 

few miles south of the preserit mining district and 

in the early stages pfbduced a OTllapsed caldera 

accaipanied by a thick welded tuff. A later conposite 

cone which filled and coveted the caldera may 

have attained a height of 13/000 ft - 16,000 ft. 

Itie present day topography of the carbonate rbcks 

may be very similar to that vîcii was for a long

•Edmis-tjon 

period of time buried 'and preserved 'by -the. volcanic 

rocks (Morris, 1978; personal communication). The 

tanperature of the ore- depositing fluids is telieved 

to have been slightly more than 200'C. 

The major geoipgic structures at Tintic include 

.folds and faults related to the overthrusting of 

the Sevier orogeny, normal faults which preceded 

the Oligocene volcanism, mineralized faults andfissures 

associated with the volcanism, and 

postmineral Basin-and-Range normal faults (Morris 

;and Mogensen, 1978) i The ore bodies in the Main 

Tintic subidistrict occur along five 'north-nor the ast 

trending asnes. Within these .zones, irKJividiial ore 

bodies are localized at the intersections of 

obscure fissures and bedding plane faults with 

other premineral structures and with., favorable 

carbonate beds,. Localization of ore at fault 

intersect ipns is related to increased permeîlity 

and the existence of open spaces in fault breccia, 

while the localization in favorable :b'eds is due tb 

Ch'emi.(:al reactions involving the hydrothermal fluid 

and host rock. 

Figure 2 is a longitudinal section along bne, of' 

the major ore zones and may be considered as the 

fossilized imprint of a gepthermal'reservoir. 

The'general direction of fluid roovenent is believed 

t'o have, been' frcm south to north, .away fron the 

cjenter of. igneous activity.- This is support^ -by 

horizontal zonation of both ore and gangue mirierals. 

Hbwever, Morris (1968) states that :there is 

evidence that hot waters rose from many centers 

with in the; district ar^ extended, great distances 

along bedding plane faults and bjher minoir 'features. 

Possible flow paths for the. hot waters 

(author's interpretation) are indicated ,bn' the 

section. Most of the ore bodies shown on the 

section, horizontal ,aS well as- vertical,, ,are pipe 

shaped. 

Five .distinct stages of wall rock alteration have 

been .described -at Tin'tic (tovering, 1.949). /These 

are: [ T) an Early-Ba'rren stage in" which .lirnestpne 

was altered to hydrothennal dolomite,' (2) a 

Mid'-Barreh, argillic. stage in -which igneous rocks 

were altered to clay minerals a«3 ,the- rema;iriihg 

cal,cite. and dolomite' cement was leached •from 

syngenet,i"c and^ Kydrothe'nnal .doiCmlftes creating 

"sands" of doloraite grains; (3) a Late-Barren 

•s.tage chiefly result,ing in the silicification of 

carbonate rb'ck.s; (4} .ah -.Ear.ly-Prpd.ue.tive sta_ge 

chara

were thrust eastward over Mesozoic strata during 

the Sevier orogeny and buried teneath andesites 

from a nearby major volcanic center during the 

mid-Tertiary. A major thrust fault, the Pavant 

thrust, is exposed in the Pavant Range north of the 

KGRA. Paleozoic rocks in the upper plate were 

overturned during thrusting and can te seen exposed 

above outcrops of Jurassic Navajo sandstone 

(Crosby, 1959). Volcanism was renewed during the 

Pliocene and Pleistocene with several rhyolitic 

eruptions to the west in the Mineral Range and to 

the northwest in the southern Sevier Desert. 

The youngest volcanic feature in the area is a 

Quaternary basaltic cinder cone three miles west of 

the area currently teing explored by Union. 

A large, shallow thennal gradient anomaly is known 

to exist at Cove Fort. Shallow holes drilled by 

Union and now available from UURI have tenperatures 

of up to 119'F at a depth of 300 ft. The anonaly 

appears to extend several miles to the north, v*iere 

Hunt Energy drilled a geothermal test in 1978, and 

to the northwest in Paleozoic strata in the upper 

plate of the Pavant thrust. There have been 

reports that deeper temperature holes drilled on 

the extensions of the anonaly tecome isothermal 

when the water table is encountered at a depth of 

about 1,000 ft. Apparently a large horizontal flow 

of warm water is taking place at the water table in 

the carbonates. 

Exploratory drilling at Cove Fort has found largescale, 

secondary porosity and permeability in 

dolomites to a depth of 5,221 ft. Porosity is 

present in the form of fractures, breccia zones, 

zones of dolomite sanding and caverns. There may 

not yet te enough control to establish the continuity 

of major fractures or the role of folding in 

the creation of secondary porosity. Water appears 

to descend rapidly to depth along some structures, 

te heated, and then return to shallow depths along 

other structures where it spreads out laterally in 

permeable carbonates creating a large thermal 

gradient anomaly. This is basically the model 

proposed by Morris (1968) for Tintic. The structures 

associated with water movement at Cove Port 

appear to te similar to those found at Tintic and 

it is likely that additional drilling and subsurface 

geology at Cove Fort will further add to the 

similarities tetween the two areas. The mciximura 

tenperature found at Cove Fort to date is about 

350'F in a contact metamorphic marble near the' 

bottom of the 7,735 ft well. A weak flow of 43,000 

Ibs/hr was produced frcm this zone during a flow 

test. The temperatures and pressures associated 

with ore deposition at Tintic are telieved to have 

been greater than those yet found at Cove Fort 

but were probably similar to those found in other 

geothermal fields. The problem at Cove Fort 

appears to te that the carbonates are too porous 

and permeable,' allowing rapid convection and an 

early cooling of the deep reservoir. 

BEX3WAWE AND CARLIN 

All of the productive wells drilled at the Beowawe 

KGRA prior to 1974 were completed in an area of 

fault intersections near the Beowawe Geysers. 

These wells bottomed in either Tertiary basalts ard 

andesites or underlying siliceous rocks of the 

183 

Edmiston 

Western Assemblage assigned to the Valmy Formation 

(Ordovician). In early 1974, Chevron drilled a 

9,551 ft test which was designed to intersect the 

Roterts Mountains thrust near its intersection with 

the Malpais fault. This well, the Chevror>-ATR-Ginn 

No.1-13, encountered two lost circulation zones 

near TD and was believed to have bottomed in a 

fault zone. A successful drill stem test was 

conducted. Geologists familiar with Beowawe 

have since debated whether the well intersected the 

Malpais fault zone or fractures related to the 

Roterts Mountains thrust. Some geologists have 

also questioned the reservoir potential of the 

underlying cartonates. The Carlin gold deposit, 

located 28 miles northeast of Beowawe, can te used 

as an exploration model to gain insight into the 

geology of the geothermal reservoir at Beowawe. 

At Carlin, microscopic disseminations of gold are 

found in altered dolomites of the Roterts Mountains 

Formation (Silurian) in a window of the 

Roterts Mountains thrust. The Roterts Mountains 

is variously included in either the Eastern 

(Carbonate) Assanblage or the Transitional Assanblage 

in the geologic literature of the region. 

The geologic section above the ore deposit is 

reconstructed in Figure 3 which is based on a 

figure from Hausen and Kerr. Hausen and Kerr state 

that penneable horizons in the Roterts Mountains 

Formation provided a favorable environment for 

mineralizing solutions which had travelled up high 

angle normal faults ard which subsequently leached 

calcite and deposited clay minerals and silica. 

Noble and Radtke (1978) state that the temperature 

of the fluids was 175*-225*C. Unconformably 

overlying the ore horizon in the mine area is the 

Popovich Formation (Devonian) which is a gray 

fossiliferous, medium bedded, locally dolomitic and 

silty limestone. Hydrothennal fluids invaded the 

Popovich along its base and along joints and 

fractures with subsequent calcite leaching and 

silica deposition, but the fabric of the rock was 

not totally, altered and it is not an important 

ore host. 

The Itoterts Mountains thrust separates the Popovich 

from the overlying Vinini Fonnation of the Western 

Assemblage which was thrust eastward into its 

present position. Hausen and Kerr state that the 

thrust is about 10 to 20 ft thick and consists of 

bleached, brecciated and iron stained rock rubble. 

Cartonate minerals have been leached from the fault 

zone and frcm adjacent beds telow the thrust. They 

conclude, and Noble concurs, that the thrust plane, 

although not an important structure in the localization 

of ore, did serve as a conduit for migrating 

solutions over a long period of time. The Vinini 

Fonnation at Carlin consists of siliceous shales. 

In other areas the Vinini usually contains minor 

quartzites and limestones. Following the main 

period of hydrothennal activity there occurred a 

later stage of acid leaching related to boiling 

of the fluids as at Cove Ftirt arxJ Tintic (Noble 

and Radtke, 1978). This resulted in the leaching 

of dolomite as well as calcite, intense argillic 

alteration, and precipitation of quartz in the 

shallower part of the alteration zone. Details of 

the origin of the Carlin deposit are given in a 

paper by Radtlce, Rye and Dickson (in press). The 

leaching of calcite at high temperatures has been

Edmiston 

VININI FM (SILICEOUS ASSEMBLAGE) 

I ' I ' I ' I ! I ',0:;:(CABBOWATE ASSEMBLIES 

-J - .1 , I 1 -• - • . • - . • • • • • • - • r- T- -T • 1 * 

I I ' ' i l l T T J I 1 ' I . ' . ' . ' • . ' 

r ' I l,',','.'.l,l|l.l|'??n 

111 

ALTERATION ZONE - LEACHING OF 

CALCITE. DEPOSITION OF CLAY AND 

' SILICA -HIGHLV PERMEABLE 

CC 

Fig, 3 - Reconstructed section at Carlin Mine, 

(Modified after Hausen and Kerr, 1968. 

Used by permission of AIME.) 

oteerved in laboratory studies by Radtke (1979, 

personal oonmunication) and Tewhey, et al. (1978). 

Data from the Ginn 1-13 and a subsequent well, 

the Rossi 21-19, also drilled by Chevron, are 

given elsewhere in this volume by M. A, Lane, 

Figure 4 is a section based on these wells using 

the geology of the Carlin area as a guide. 

The tenperature regime in Figure 4 is canplicated 

by a flow component normaLl. to the section in the 

direction of the Beowawe Geysers, Figure 4 

shows a deep reservoir at Beowawe in the brecciated 

rock of the Roterts Mouintains thrust and in altered 

limestones teneath the thrust fron which calcite 

has teen leached. For sinplicity the potential 

reseirvoir zone in the cartonates has been placed 

immediately below the thrust. However, this zone 

may te separated frcm the thrust by beds of less 

penneable limestone as at Carlin. The depth of the 

thrust is based on a thickness of about 6,000 ft 

for the Western Assemblage which is consistent 

with sections drawn to the south in the Cortez 

Quadrangle by Gilluly and Masursky (1965). 

The shales and quartzites of the Valmy Etinnation 

may furnish an element which appears to te missing 

at Cove Fort - a cap rock for the cartonate reservoir. 

CONCLUSIONS 

Geothennal reservoirs in cartonate rocks differ 

from other geothennal reservoirs in that secondary 

porosity and permeability may be enhanced by 

leaching of the cartorwtes by the fluids at high as 

well as moderate temperatures. Unfortunately, 

carbonate reservoirs appear to lack the self 

sealing properties of reservoirs in siliceous rocks 

so that an external cap rock is required for a high 

temperature reservoir. In carbonate rocks, the 

greatest potential appears to te for large, moderate 

tenperature reservoirs. 

ACKNOWLEDGMENTS 

The author gratefully aclcnowledges the assistance 

of Drs, H. T. Morris and A, S. Radtke of the 

USGS and Mr. Larry Noble of the Carlin Gold Mining 

200 

Fig. 4 - Interpretted geologic section at Beowawe, 

CcHnpany during preparation of this paper. However, 

tte conclusions regarding geothennal exploration 

are solely the author's. 

REFEREi^CES 

Celati, R., Squarci, P., Taffi, L., and Stefani, 

G. C, 1975, Analysis of water levels and 

reservoir pressure measuranents in geothermal 

wells: SeoorxJ UN Symposiura on tte Development 

and Use of Geothermal Resources, San Francisco 

Proceedings, Lawrence Berkeley Lab., Univ. 

of California, p. 1583-1590. 

Crosby, G, W., 1959, Geology of the south Pavant 

Range, Millard and Sevier counties, Utah: 

BYU Geol. Studies, V.6, no.3. 

Gilluly, J., and Masursky, H,, 1965, Geology 

of the Cortez quadrangle, Nevada: U.S. Geol. 

Survey Bull. 1175, 117p. 

Hausen, D. M., and Kerr, P,, 1968, Fine gold 

occurrence at Carlin, Nevada: _in. Ridge, J, 

D,, ed,. Ore deposits of the United States, 

1933-1967: Am. Inst. Mining, Metall. Petroleum 

Engineers (AIME). 

Lovering, T. S., 1949, Rock alteration as a guide 

to ore-East Tintic district, Utah: Econ. 

Geology Mon., 1, 65 p. 

Morris, H. T., 1968, The Main Tintic mining 

district, Utah: ^Jl Ridge, J. D, ed.. Ore 

deposits of the United States, 1933-1967: 

Am. Inst. Mining, Metall. Petroleum Engineers 

(AIME), 

Motnris, H, T,, and Mogensen, A, P., 1978, Tintic 

raining district, Utah: BYU Geol. Studies, 

V,25, part 1. 

Noble, L. L. , and Radtke, A, S,, 1978, Geology 

of the Carlin disseminated replacenent gold 

deposit, Nevada: Jri Shawe D,R,, ed.. Guidebook 

to mineral deposits of the central Great 

Basin: Nevada Bureau of Mines and Geology, 

Report 32. 

Radtke, A, S,, Rye, R. 0.,and Dickson, F. W., 

Geology and stable isotope geochanistry of the 

Carlin gold deposit, Nevada: Econ, Geol. (in 

press). 

Tewhey,J. D,, Chan, M. A,, Kassameyer, P. W,, Owen, 

L. B,, 1978, Development of injection criteria 

for geothennal resources: Geothennal Resources 

Council, Transactions, Vol, 2,

Geothermal Resources Counail, TRANSACTIONS Vol. 4, September 1980 

WATER GEOCHEMISTRY AT CASTLE HOT SPRINGS, ARIZONA 

Richard L. Satkln, Kenneth H. Wohletz and Michael F. Sheridan 

Department of Geology, Arizona State University, Tempe, Arizona 85281 

ABSTRACT 

A geochemical survey of springs and wells 

in the Castle Hot Springs area, Arizona, shows 

that three groups of waters can be distinguished 

by salinity and chemistry. The thermal waters 

of Group I range from 640 to 820 ppm TDS, and 

the waters contain high concentrations of Si02, 

Li"*", and F~. The non-thermal waters of Group 

II range from 380 to 580 ppm TDS and contain 

low concentrations of Si02, Li"*", and F~. The 

non-thermal waters of Group III range from 

1600-1650 ppm TDS and contain the highest concentrations 

of Li+, Cl", and SO^^'^. 

The discrepancy between the low measured 

surface temperature at Castle Hot Springs, and 

the high temperatures estimated from chemical 

geothermometry suggest thermal waters may have 

cooled either hy conduction, boiling or mixing. 

TKe chalcedony mixing raodel yields a"^reservolr 

temperature of 95°C and a cold water fraction of 

56%. 

INTRODUCTION 

Castle Hot Springs ie located 70 km northwest 

of Phoenix, Arizona (Figure 11. It is presently 

being evaluated for direct-use geothermal 

development of the resource for space heating and 

cooling. The results of hydrogeocKemtcal sampling 

of thermal and non-thermal springs and wells in 

the area are presented. 

GEOLOGIC SETTING 

The geologic setting of Castle Hot Springs 

has been discussed by Sheridan et al. (1979);. Recent 

detailed geologic mapping has documented a 

low-angle slump fault displacing an allochthonous 

block of Precambrian granite on top of a sequence 

of Tertiary volcanic rocks. The allochthonous 

block has been altered and is strongly brecciated 

and jointed resulting in increased permeability. 

Mixing of hydrothermal fluids and cold meteoric 

water may be significant along this low-angle 

fault. Nielson and Moore (1979) have described a 

similar geologic situation at the Cove Fort-Sulphurdale 

geothermal system in Utah. They suggest 

that the allochthonous rocks may serve as a thermal 

cap on the system separating a convective ther- 

177 

mal regime beneath the low-angle fault from a 

zone of conductive heat transport and probable 

fresh water influx above the principal fault 

zone. 

Califofnie 

Figure 1. 

Mexico 

Utah 

•* Cjstle Hot Sprirgs 

• PhoeniK 

"""^-^ 0 

""-^.^ 

100 Km 

_ 

Colorado 

New 

Mexico 

Location map of Castle Hot Springs, 

Arizona. 

HYDROLOGIC SETTING 

The thermal waters of Group I display similar 

physical and cheraical characteristics. The 

waters of Group I are: Castle Hot Springs, Alkalai 

Spring, Henderson Ranch Spring and the Dodd 

Well. The thermal waters occur along a 0.8 km 

alignment trending N.45°W. which coincides with 

the trend of a major fault system bounding Precambrian 

crystalline rocks and Tertiary volcanic 

rocks. The thermal springs all emanate at an elevation 

of 658 meters along the same fault system 

suggesting an apparent hydrostatic relationship. 

The thermal waters display a homogenous chemistry 

which indicates they probably originate from the 

same geothermal reservoir. 

WATER SAMPLING AND ANALYTICAL PROCEDURE 

An important aspect of this investigation is

Table I. Chemical analyses and calculated reservoir temperatures of springs and wells in the Castle Hot Springs, area, Arizona. 

Analyses are in ppra (mg/l) unless otherwise noted. 

Name,Group (I,II,III) 

Location 

Temperature 

pH (field) 

SiO, 

Na+^ 

K^ 

Ca++ 

l-lC 

Li+ 

r 

cr 

80^= 

°C 

Geothermometry °C 

Si02(quartz ,adiabatic) 

Si02(quartz ,conductive) 

Si02(chalce dony) 

Na-K-Ca (B" 1/3) 

Na-K-Ca (B=V3) 

Na-K 

Castle Hot Springs,! 

T8N,RlW,34,SW5s,SW5s 

54,7 

7.85 

61.27 

208,03 

5,42 

32.42 

2.32 

0.34 

8.45 

145 

211 

110.93 

111.54 

82.38 

117.08 

75.94 

77.30 

Name,Group(1,11,III) Chuck's Well.!! 

Location T7N,RlW,3,SW^,SW>s 

Teniperature °C 

pH (field) 

Si02 

Na"*" 

K+ 

Ca^ 

Mg++ 

L1+ 

F" 

Cl" 

S0,° 

22.3 

7.45 

51.03 

136.89 

3.83 

64.47 

19.29 

0.16 

3.83 

81 

170 

Geothermometry C 

S102(quartz,adiabatic) 103.33 

SiO-(quartz,conductive)I 02,76 

ni02(chalcedony) 72,91 

Na-K-Ca (6=1/3) 109.88 

Na-K-Ca (8=4/3) 48.01 

!Ia-K 81.80 

Henderson Ranch Spring,! 

T8N,RlW,33,NW!i: 

29.2 

7.70 

60.42 

234.47 

7.31 

39.72 

2.23 

0. 55 

7, 45 

150 

299 

110.34 

110.85 

81.63 

124.68 

82.61 

88.86 

Menudo Spring,II 

T7N,RlW,14,NWS£,NW5i: 

21.8 

7.55 

75.55 

25.37 

1.70 

82.82 

16.37 

0.04 

0.45 

39.8 

23.7 

119,95 

122,11 

93,88 

120.60 

10.93 

148.08 

Layton Seep,II 

T7N,R2W,l,NW5s,SWJi 

20.6 

8.00 

39.11 

15.30 

1.62 

88.78 

14.08 

0.06 

0.30 

11.3 

8.6 

92,92 

90,69 

60,00 

132.28 

5.44 

193.76 

Alkalai Spring,! 

T8N,RIW,33,NWit,SE 

31,2 

7,85 

70,78 

214,67 

6,32 

15,78 

0,23 

0,42 

11,88 

135 

209 

117.10 

118.76 

90.22 

127.50 

97.95 

85.09 

Windmill Well,II 

T7N,RlW,3,SV^,SW!s 

20.5 

7.55 

42.22 

93.54 

3.45 

70.15 

22.26 

0.11 

2.11 

50.2 

122 

95.87 

94.08 

63.61 

115.13 

40.37 

100.40 

jsquite Drip,! 

rN,RlW,33,NW!i,SE5s 

26,8 

7,90 

71.39 

253.88 

7.38 

17.40 

0.48 

0.54 

12.54 

150 

228 

117.47 

119.19 

90.70 

128.64 

103.32 

84.26 

Dodd Well,I 

T8N,RlW,33,NW5i:,NWJj 

23.6 

8.00 

62.69 

239.26 

7.29 

25.68 

0.43 

0.49 

8.19 

142 

288 

111.89 

112.67 

83.60 

127.05 

• 92.73 

87.34 

Casa Rosa SprlngH! Dripping Springlll 

T7N,RlW,14,NEHs,SW!!; T7N,R1W, 14,NW!i,NEii 

18.9 

7.70 

36.82 

539,54 

13,86 

144.04 

1.27 

1,14 

4.0 

525 

385 

90.62 

38,06 

57,20 

119,30 

84.58 

76.42 

24.6 

7.25 

30.50 

494.52 

13.28 

137.90 

7.01 

1.05 

3.8 

521 

372 

83.65 

80.09 

48.78 

120.22 

83.15 

79.20 

I

to test the variation of water chemistry with 

tirae. Tanperature measurements and water samples 

collected at each sampling site were taken as 

close to the source as possible and at the same 

location throughout the sampling period. Temperatures 

were measured with an Extech 1200 digital 

thermometer. The pH was determined in the 

field on an unfiltered sample with a Photovolt pH 

meter 126A. 

Water samples collected for chanical analysis 

were analyzed for Si02, Na"*", K^, Ca"*^, Mg"''^, and 

Li'*' on a Varian 1250 Atomic Absorption. Spectrophotometer. 

F~, Cl", and SO^^ were analyzed on a 

Dionex 10 Ion Chromatograph. Total dissolved 

solids were deteraiined on filtered uncreated samples 

by the residue-on-evaporation method (Rainwater 

and Thatcher, 1960). 

GEOCHEMISTRY OF THERMAL AND NON-THERMAL WATERS 

The thermal waters (Group I) are a sodiumchloride-sulfate 

type. .The waters have relatively 

high concentrations of Si02, Li"*", and F" and 

Satkln et al. 

low Mg (Table I). In contrast, the non-thermal 

waters (Group II) are enriched in Ca"*"*", and Mg"*^ 

and have lower concentrations of SiOo, Li"*", and 

Within the non-thermal group of waters a subgroup 

of waters (Group III) can be distinguished 

by their high salinity. Both Casa Rosa and Dripping 

Springs are highly enriched in Na"*", Ca'*^, Li'*; 

C1-, and S0/;°. It is possible that these waters 

follow a different hydrologic flow pattern. They 

may derive their high salinity from, dissolution 

of limestones and evaporites that crop out 20 km 

to the west. A heavy isotopic signature may confirm 

this suggestion. 

The measured surface temperature at Castle 

Hot Springs ranges between 47.6°C and 55.4''C with 

a flow rate of 1300 l/min (340 gal/min). The 

springs were sampled periodically (3-4 week intervals) 

to test the variation of chemistry with 

time. It is evident from the chemical analyses 

listed in Table II that there has been no significant 

change in the main spring systan's chemistry. 

Table 2, Chemical variation through time at Castle Hot Springs, Arizona. Analyses in ppm (mg/l). 

Date 

Temp. °C 

pH 

K 

C^tt Mg^ 

Li^ 

F 

Cl" 

'% 

400T 

"§ 300 

a 

o. 

200 

lOO 

0 

10/9/79 

51.3 

7.60 

59.70 

209.08 

4.98 

30.33 

2.36 

n.d. 

8.50 

147 

212 

10/24/79 

55.4 

7.65 

63.48 

208.75 

5.49 

34.04 

2.99 

n.d. 

9.16 

155 

230 

Note: n.d. - not deterrained 

o o 

m 

Ca"*^ (ppm) 

11/27/79 

54,7 

7.85 

61.27 

208.03 

5.42 

32,42 

2.32 

0.34 

8.45 

145 

211 

Group III 

Group II 

Figure 2. Water chemistry Ca"*"^ versus SO^. 

o 

12/20/79 

52.7 

7.75 

60.27 

210.89 

5.50 

31.89 

2.63 

0.33 

8.70 

141 

211 

179 

1/9/80 

53.4 

7.70 

58.68 

195.27 

5.55 

29.46 

2.37 

0.32 

8.53 

140 

206 

1.2T 

0.9 

0.6 

0.3 

» 

2/3/80 

52.1 

7.85 

59.37 

199.64 

5.35 

29.78 

2.32 

0.31 

8.61 

141 

200 

3/7/80 

49.3 

7.80 

61.79 

202.12 

5.61 

29.52 

2.41 

0.31 

8,47 

138 

196 

Group I 

Croup II 

4/10/80 

47.6 

7.85 

62.01 

221.56 

5.39 

31.07 

2.43 

0.30 

8.31 

140 

189 

Group III 

o 

o 

Cl" (ppm) 

Figure 3. Water chemistry Cl" versus Li 

5/12/80 

47.7 

7.85 

62.25 

202.93 

5.54 

31.46 

2.50 

0.32 

8.64 

143 

206 

o

Satkln et al. 

GEOTHERMOMETRY 

The temperature of the geothermal reservoir 

at Castle Hot Springs has been estimated by the 

silica geothermometer (Fournier and Rowe, 1966), 

the Na-K, and Na-K-Ca geothermometers (Fournier 

and Truesdell, 1973, Table I). The calculated 

solubility of chalcedony closely approximates the 

silica content at Castle Hot Springs. Thus the 

chalcedony geothermometer yields the most reliable 

estiraate of water temperature at depth. 

Large travertine deposits occur near Castle 

Hot Springs. The deposition of calcium-carbonate 

will decrease the calcium ion concentration and 

should yield artificially high tanperature estimates. 

However, the Na-K-Ca geothermometer estimate 

closely resembles both the Na-K and Si02 

geothermometer estimates. Travertine may not be 

deposited during the rapid ascent of the fluid, 

just at the surface as the dissolved CO2 bubbles 

off at atmospheric pressure and lowered temperature. 

The chalcedony geothermometer gives an estimated 

subsurface teraperature of 82°C which Is 

above the surface temperature at Castle Hot 

Springs (Sl'C). This low surface water temperature 

may possibly be due to heat loss through 

conduction, boiling, or mixing. Because of the 

large flow rate at Castle Hot Springs, heat loss 

through conduction may be neglible. Cooling the 

ascending thermal water by mixing with cool 

groundwater is more probable because numerous 

intersecting faults may provide passageways. The 

graphical mixing model solution (Fournier and 

Truesdell, 1974) using chalcedony as the dissolved 

silica phase in equilibrium with the hot 

springs' water yields a subsurface tanperature of 

95°C and a cold water fraction of 56%. This temperature 

is similar to the calculated geothermometer 

temperatures. 

150r 

Group II 

Group I 

o 

Cl" (ppm) 

Group III 

FlEure 4. Water chemistry Cl versus Ca 

180 


The authors are indebted to Keenan Evans for 

the anion analysis of water samples. The Arizona 

State University Foundation has cooperated with 

this work. Financial support for this work is 

provided by the Department of Energy through the 

Arizona Bureau of Geology and Mineral Technology 

Agreenent No. DE-F107-79ID 12009. 

REFERENCES 

Fournier, R.O., and Rowe, J.J., 1966, Estimation 

of underground temperatures from the silica 

content of water from hot springs and wet 

steam wells: Am. Jour. Sci., v. 264, p. 585- 

697. 

Fournier, R.O., and Truesdell, A.H., 1973, An 

empirical Na-K-Ca geothermometer for neutral 

waters: Geochim. et Cosmochim. Acta, v. 37, 

p. 1255-1275. 

, 1974, Geochemical indicators of subsurface 

temperature - Part 2. Estimation of 

temperature and fraction of hot water mixed 

with cold water: U.S. Geol. Survey Jour. 

Research, v. 2, p. 263-269. 

Rainwater, F.H., and Thatcher, L.L., 1960, Methods 

for collection and analysis of water samples: 

Geological Survey Water-Supply Paper 1454, p. 

269-271. 

Nielson, D.L., and Moore, J.N., 1979, The exploration 

significance of low-angle faults in the 

Roosevelt Hot Springs and Cove Fort-Sulphurdale 

geothermal systems, Utah: Geothermal 

Resources Council, Transactions, v. 3, p. 503 

503-506. 

Sheridan, M.F., Wohletz, K.H., Ward, M.B., and 

Satkln, R.L., 1979, The geologic setting of 

Castle Hot Springs, Arizona: Geothermal Resources 

Council, Transactions, v. 3, p. 643- 

645. 

t 

15 

12 

6 

o 

0^ 

TDS (ppm) 

Group III 

Figure 5. Total dissolved solids versus K

Geotiiermal Resources Council, 'Ili'UiSACTIOiiS, Vol. 3 September 1979 

AN ANALYSIS OF GRAVITY AND GEODETIC CHANGES DUE TO RESERVOIR DEPLETION 

AT THE r.EYSERS, NORTHERN CALIFORNIA 

Roger P. Denlinger, William F. Isherwood, and Robert L. Kovach 

ABSTRACT 

In this paper gravity and geodetic data are 

combined with reservoir engineering studies to 

place upper and lower bounds on the volume and 

pore fluid mass changes within the depleted portion 

of che steam reservoir at The Geysers. We 

combined the gravity and temperature data to 

constrain the changes in pore fluid mass distribution 

due to fluid depletion, and thus 

limited the drainage volume to lie between 15 

and 25 cubic kra. We then modeled the surface 

geodetic data to determ.ine values of strain 

between 3. and 8. X 10"^ for these drainage 

volumes. We determined that this strain could 

be induced either mechanically or thermally, 

and there 'is presently no way of distinguishing 

thermal from mechanical strain. 

Since 1974, the average production rate at The 

Geysers steam field in Northern California (Figure 

1) has been nearly 90 million kg of steam per day 

(Lippman and others, 1977). This large fluid 

withdrawal rate has caused changes in mass and 

volumetric strain within the depleted reservoir 

volume. From 1973 Co''1977, time changes in pore 

pressure, surface strain (Lofgren, 1979), and 

gravity (Isherwood, 1977) occurred, while the 

reservoir•temperature did not measurably change. 

In this paper, the gravity and geodetic data 

from 1974 to 1977 are combined with reservoir 

engineering results (VJeres, 1977) to determine the 

pore fluid deficit and strain within the drainage 

volume. Previously, (Isherwood, 1977; Hunt, 1977) 

it has been demonstrated that decreases in observed 

gravity with time reflect mass redistribuCion and 

deficits within some depletion volume. By comparing 

the total mass deficit measured from the 

gravity flux (found be integrating the gradient of 

the potential over some bounding surface) with the 

net mass produced, the recharge was estimated 

(Isherwood, 1977). Here we combine the gravity 

changes with well data to constrain the drainage 

volume between 15 and 25 cubic km. Wc then 

analyzed the geodetic data to determine the 

reservoir strain within the possible range of 

reservoir voluraes. These concepts are summarized 

in Table 1. 

At The Geysers, mapped values of maxima in 

subsidence, gravity change, pore pressure decline 

overlap. Figure 2 compares the decreases in observed 

gravity and pore pressure decay due to 

U.S. Geological Survey 

Menlo Park, CA 94025 

153 

steam production. Isherwoods' (1977) previous 

analysis of this data determined that (1) the 

gravity changes were too large to be due solely 

CO a deep water table below the producing zone 

penetrated by the wells, and (2) the gravity flux 

implied a mass deficit equal to the met mass produced, 

suggesting negligible recharge. 

The lack of a measurable temperature change 

(plus or minus 3 degrees Celsius) limits the 

araount of water which has flashed to sCeam during 

production to less than 0.5% of the bulk rock 

volume. Yet reservoir engineering data imply thac 

water flashes to steam to supply the fluid produced 

by the wells (Weres, 1977). Since the heat 

energy required in the phase transition from water 

to steam must come from the rock matrix, the lack 

of a measurable temperature change limits the 

change in reservoir liquid content due to steap 

production to that allowed by the error in the 

temperature measurements (Weres, 1977; Denlinger, 

1979). The steam could come from a deep water 

table in this case, but this is inconsistent with 

the magnitude of the time changes in the gravity 

mentioned above. 

9 lp20»4O90«07DaaK« 

I—I I I—1—I I I I 

Figure 1. Index map, showing the region of discussion in 

this paper.

Denlinger 

We modeled the gravity data using the thermal 

constraints above on the mass distribution. The 

maximum mass change due to water flashing to steam 

over the bulk reservoir volume, which is consistent 

with the lack of a measurable temperature change 

is .004 g/cc. Values of this magnitude were used 

to model the time changes in the gravity and the 

results are shown in Table 2. The value of .002 

g/cc represents a lower bound in die modeling as 

the mass distribution is then too diffuse to 

reproduce the gravity amplitudes shown in 


Q 400-900 pilo 

O 300-400 pilo 

@ < 300 pclo 

I22»4S' 

POWER PLANT UNIT 

deficiency 

.002 a/cc 

II OBSERVED CHANGE IN ORAVITT 

(in mlcrogol, ) 

Figure 2. Time changes in surface gravity between 

1974 and 1977 and the pore pressure decay near the 

top of the steam reservoir (from Lippman and others, 

1977). 

TABLE 1, A STUDY OF RESERVOIR DEPLETION AT THE GEYSERS CEOTHERMAL FIELD, 

PHYSICAL CHANCES 

Pore fluid mass 

de£iciency due 

CO production. 

Volumetric strain 

within Che 

reservoir. 

Change in temperature 

of reservoir during 

production, and change 

in enthalpy of 

produced steam. 

SURFACE MEASURQIENT 

Change in gravity 

with clme. 

Geodetic measurement 

of surface strain 

with time. 

TemperaCure and 

pressure measurements 

of steam vithin wells. 

RESULT OF ANALYSIS 

A tradeoff between 

a depleted reservoir 

volume and some 

uniform mass 

deficiency. 

For uniform dilatation, 

a tradeoff occurs 

between volume 

and strain for a 

given maximum strain 

amplitude. 

Limits on the pore 

fluid mass changes 

due to water flashing 

to steam within the 

reservpir volume. 

154 

.003 9/cc 

.004 g/cc 

.04 g/cc 

(water 

saturation) 

RESOLTS FRCH KODELING OF RESERVOIR GRAVITY CHANGE 

POR A CYLINDRICAL VOLIHE. 

radius 

1.8 km 

2.1 km 

1.5 km 

1.7 km 

I.S km 

2.3 km 

1.0 km 

height 

3.7 km 

2.7 km 

3.7 km 

2.7 km 

3.7 km 

2.2 km 

0.6 km 

deotl 1 to too 

0.0 kn 

0.0 km 

0.5 

0.5 

km 

km 

1.0 kn 

1.0 kn 

1.5 km maximum 

We also modeled the geodetic strain 

to determine the volumetric strain within 

the depleted reservoir volume. At The 

Geysers, horizontal contraction and surface 

subsidence measured by Lofgren (1979) 

overlie the portion of the reservoir 

volume depleted by steam production, 

(Figure 3), as shown by pore pressure 

decay (Lippman and others, 1977). 

By modeling the geodetic data, 

(assuming simple dilatation), we calculated 

scrains up to 10"^ within the depleted 

reservoir volume. By assuming that the 

reservoir strain is a raechanical response 

to increased effective stress as the pore 

pressure decays, we also calculated a bulk 

or "framework" modulus for the reservoir 

matrix. The change in effective stress 

may be calculated from.the pore pressure 

change (which is estimated from data 

presented by Lippman and others, 1977), 

and a value for the "intrinsic" bulk 

modulus of the reservoir rock (Rice and 

Cleary, 1976). For an intrinsic bulk 

modulus of the reservoir ro,ck we used lab 

measurements of the compressional velocity 

of Franciscan graywacke (Stewart and 

Peselnick, 1978) combined with values of 

Poissons ratio form earthquake data (Majer 

and McEvilly, 1978). The scrain we calculated 

for a given reservoir volume was 

then combined with the changes in effective 

stress to produce a value for the bulk 

modulus of the reservoir matrix. The bulk 

moduli determined in this way from the 

geodetic data are listed in Table 3 for 

several reservoir voluraes (which were 

determined using the gravity and temperature 

measurements). 

Bulk moduli obtained from microseismic 

monitoring within the reservoir 

(Majer and McEvilly, 1978) are an order 

of magnitude larger (bulk modulus about 

3.x 10^.bars), and lie between lab values 

calculated from Stewart and Peselnick 

(1978) and calculated bulk moduli for the 

reservoir matrix. The bulk moduli determined 

from seismic measurements therefore 

produce much smaller strains given the 

observed changes in pore pressure and 

calculated changes in effective stress.

Q 400-SOO p

TABLE 3. RESULTS OF MODELING RESERVOIR STRAIN WITH PURE DILATATION. 

SHAPE. mass strain (Av/V X 10"^) 

radius height volurr^ deficiency d"0.5 tan

1 -.— 

ABSTRACT 

Average temperature-depth gradients in wells penetrating 

the Mississippian Madison Limestone in 

Edgemont, South Dakota, are 4.7°C/I00 m, whereas 

the average gradient in the Black Hills area is 

2.6OC/100 m. Chemical analyses of ground water 

from forty-one Madison wells and springs were 

obtained to define the geochemical characteristics 

of the low-temperature (

Knirsch 

Table 1. Continued 

Location 

Well Name 

Zn 

Al 

S2- 

HCO3 

F 

Cl 

SO. 

Si02 

pH 

9S-2E-laa3 

Edgemont-Burlington 

— 

— 

— 

181 

0.8 

139 

300 

34 

7.0 

All data reported in mg/l 

n.d. = not detected 

R.R. 

Lowest detectable limits: 

Li = 0.02 Sr = 0.02 Ni = 0.05 

Rb = 0.13 Co = 0.02 Fe = •- 0.01 

9S -2E-lacdbl 

Edgemont-City #1 

n.d. 

n.d. 

3.2 

157 

0.9 

244 

424 

45 

6.9 

Aq 

Pb 

Water temperatures ranged from 51.0 to 55.60C during 

the pumping tests. However, temperatures at 

each site did not increase significantly and the 

chemical composition of the ground waters did not 

vary significantly. Therefore, we concluded that 

increasing the discharge rate of the wells would 

not significantly alter either water temperature 

or water chemistry. 

= 0.0008 

= 0.01 

Cu 

Zn 

9S-2E-lbcdl 


n.d. 

n.d. 

0.04 

161 

1.1 

249 

465 

45 

6.8 

= 0.007 Al = 

= 0.015 S2- = 

5.0 

0.005 

9S-2E-2daal 


n.d. 

n.d. 

0.03 

177 

1.1 

284 

466 

43 

6.8 

GROUND WATERS SAMPLED WITHIN A 50-MILE RADIUS 

Of the forty-one wells and springs sampled in the 

Black Hills area, eighteen are within a 50-mile 

radius of Edgemont. The locations of four selected 

sample sites and the results of chemical 

analyses are listed in Table 2. Water temperatures 

ranged from IO.6OC to 53.30C, and temperature-depth 

gradients ranged from I.7OC/IOO m to 

4.0OC/100 m. 

Table 2. Chemical data from ground water for selected Madison wells and springs within a 50-mile 

radius of Edgemont, South Dakota 

Location 

Well/Spring Name 

Depth (m) 

Temp (OC) 

TDS 

Li 

Na 

K 

Mg 

Ca 

Sr 

Co 

Ni 

HCO3 

F 

Cl 

SO4 

Si02 

pH 

All data reported 

in mg/l 

8S-5E-20cda 

Cascade Springs 

21.5 

2636 

0.08 

38 

10 

95 

549 

6.9 

n.d. 

n.d. 

183 

1.0 

52 

1490 

21 ' 

6.9 

TEMPERATURE-DEPTH GRADIENTS 

A true geothermal gradient for the Black Hills was 

not calculated, due to the lack of available heat 

flow data. Temperature-depth gradients reported 

in this summary are defined in the following manner: 

Temperature of water recorded on-site=t^^pQ 

Mean annual temperature at or near site of well= 

tMA 

Corrected temperature=tH20-tMA=tc 

Total depth of wen=d 

7S-5E-13bdd 

Evans Plunge 

32.0 

1122 

0.14 

84 

14 

44 

200 

3.2 

n.d. 

n.d. 

183 

0.9 

110 

430 

21 

6.8 

166 

10S-2E-3daal 

Black Hills 

Ordnance Depot §1 

1219 

53.3 

1024 

0.25 

182 

18 

22 

121 

1.8 

0.07 

n.d. 

156 

0.6 

308 

310 

34 

7.3 

45N-60W-20dcal 

Newcastle #1 

804 

26.1 

266 

n.d. 

2.1 

1.9 

29 

62 

0.02 

n.d. 

n.d. 

281 

0.1 

2.5 

57 

14 

7.6 

Critical depth (depth to which temperature measurement 

is affected by mean annual temperature 

or near surface thermal disturbances)=18 meters 

(Schoon and McGregor, 1974)=dQR 

Corrected depth=d-dcR=dc 

Then, the temperature-depth gradient for a single 

measurement at one well=tc/dc=G-['o. 

For most wells, more than one temperature measurement 

was recorded. In some localities, more than 

one well exists. For these cases, the temperature-depth 

gradient was averaged for all measurements 

at all wells.

This method of calculation assumes the following: 

1. Depth is a vertical distance from ground surface. 

2. Correction for mean annual temperature is independent 

of discharge rate. 

3. Water is not mixing between aquifers. 

4. Temperature equilibrium is maintained in well. 

5. Mean annual temperature influences water temperature 

at surface and influences critical 

depth as defined above. 

CHEMICAL COMPOSITION 

The results of standard mineral analyses were 

plotted on multiple tri-linear diagr'ams after 

Piper (1944). Ground waters were classified as 

either sodium chloride-calcium sulfate type, calcium 

sulfate type, or calcium-magnesium bicarbonate 

type. The bicarbonate waters were generally 

found in wells and springs near recharge areas, 

and the calcium sulfate waters were found with 

either increasing distance from recharge areas 

or in ground waters which were known to be mixing 

between aquifers. The sodium chloride-calcium 

sulfate type water was found only in Madison 

ground watiers in the Edgemont geothennal area. 

The standard mineral composition of these ground 

waters was found to be significantly different 

from that of all other sampled ground waters. 

Of all the trace elements analyzed, only lithium 

and cobalt have higher concentrations in Edgemont 

area waters than in waters at all other sites. 

Strontium concentrations in Edgemont area waters 

ranged from 1,8 to 3,4 mg/l. Although cesium and 

rubidium were detected in Edgemont ground waters, 

it was not determined whether this is significant 

as there is no data from other sampled sites. 

Aluminum, copper, lead, manganese, silver, and 

zinc were not detected in Edgemont waters, and 

additional analyses supplied by the U.S. Geological 

Survey indicated that only trace amounts of 

these elements, if any at all, occur in ground 

waters at other sites in the study area. 

GEOTHERMOMETRY 

Temperatures were calculated using the quartz and 

chalcedony geothermometers defined by Truesdell 

(1975) and the Na-K-Ca geothermometer defined by 

Fournier and Truesdell (1973). Water temperatures 

calculated using the quartz geothermometer ranged 

from 9.70c to 46.IOC above observed temperatures, 

whereas temperatures calculated using the chalcedony 

geothermometer ranged from 24.50C below to 

14.0OC above observed temperatures. Water temperature 

calculated using the Na-K-Ca geothermometer 

ranged from 41.30C below to 41.50C above observed 

temperatures. 

Table 3 lists the results of selected geothermometer 

calculations. The chalcedony geothermometer 

yielded the best correlation between observed temperatures 

and calculated temperatures. This is in 

agreerent with Fournier (1973) who found that 

chalcedony, rather than quartz, controls the dissolved 

silica content of waters below lOOOC. 

167 

Knirsch 

Most work with geothermometers has been done for 

high-temperature geothermal systems. The highest 

observed temperature in this study was 560C. No 

correlations exist between the results of geothermometer 

calculations and temperature-depth gradients. 


We wish to thank the U.S. Department of Energy and 

the U.S. Geological Survey for their assistance 

with this study. 

REFERENCES 

Fournier, R. 0., 1973, Silica in thermal waters: 

Laboratory and Field Investigations, 2£ Proceedings 

of the International Symposium on Hydrogeochemistry 

and Biogeochemistry, Japan, 1970, v. 

I, Hydrogeochemistry: Washington, DC, The Clark 

Co., p. 122-139. 

Fournier, R, 0., and Truesdell, A. H., 1973, An 

empirical Na-K-Ca geothermometer for natural 

waters: Geochim. et Cosmochim. Acta, v. 37, 

n. 5, p. 1255-1276. 

Gries, J. P., 1977, Geothennal applications on the 

Madison (Pahasapa) aquifer system in South Dakota: 

Final Report, Contract No. EY-76-S-07-1625, 

South Dakota School of Mines and Technology, 

100 pp. 

Iszler, J., Carda, D,, Skillman, D., Dunham, G., 

and Reuter, W., 1979, Western South Dakota usage 

of geothermal energy from the Madison Formation 

--final report, ET-78-S-07-1707: Department of 

Energy, Division of Geothermal Energy, Washington, 

D.C., 153 pp. 

Piper, A. M., 1944, A graphic procedure in the 

geochemical interpretation of water analyses: 

Trans., Am. Geophys. Union, 25th annual meeting, 

p. 914-923. 

Schoon, R. A., and McGregor, D. J., 1974, Geothermal 

potentials in South Dakota: S.O. Geol. 

Survey Rept. Inv. 110, 76 pp. 

Truesdell, A. H., 1975, Summary of Section III: 

Geochemical techniques in exploration Ui Proceedings, 

United Nations Symposium on the Development 

and Use of Geothermal Resources, 2nd, 

San Francisco: Washington, D.C, U.S. Govt. 

Printing Office, p. LIII-LXXIX.

Knirsch 

Spring/Well 

Edgemont Burlington R.R. 

Edgemont City §1 

Edgemont City #2 

Edgemont City #4 

Cascade Springs 

Evans Plunge 

Black Hills Ordnance Depot #1 

Newcastle #1 

Table 3. Results of selected geothermometer calculations 

T, oc Observed T, oc Quartz T, "C Chalcedony T,oc Na-K-Ca 

51.7 

51.0 

53.3 

54.4 

22.2 

33.5 

53.3 

26.1 

84.8 

97.1 

97.1 

95.0 

65.5 

65.5 

84.8 

50.8 

168 

51.8 

65.0 

65.0 

62.7 

31.4 

31.4 

51.8 

16.1 

68.1 

87.8 

94.8 

91.0 

25.4 

25.4 

85.1 

0.3

Ceothermal Resources • 

GEOCHEHISTRY OF ACTIVE GEOTHERMAL SYSTEMS IN THE NORTHERN BASIN AND RANGE PROVINCE 

ABSTOACT 

Numerous thermal springs occur in the 

northern Basin and Range Province due primarily 

to the structure and high regional heat flow. 

Dilute to slightly saline (200 to 3,000 mg/L 

TDS) Ca and/or Na-UCO, type waters, many 

associated with travertine, are dominant in 

eastern and northeastern Nevada. CO.-charged 

Na-HCO waters are particularly common along the 

eastern side of the Sierra Nevada from Long 

Valley north to Bridgeport. Moderately to very 

saline (3,000 to 35,000 mg/L TDS) Na-Cl type 

waters predominate near major topographic lows, 

Na-SO. type waters are common in western Nevada 

and in northeastern California. Na-mixed anion 

waters are common along the north side of the 

Black Rock Desert in northwestern Nevada and the 

Alvord Desert in southeastern Oregon, 

Measured temperatures in deep geothermal 

wells in the northern Basin and Range Province 

are about 14 C cooler than the average 

temperature calculated using two chemical and 

one isotope geothermometer on waters discharged 

by nearby thermal springs and shallow wells 

(

Mariner et al. 

MomfflatI 

Min 

H>0^ 150 200 Ullii 

as 0 ^ .so 100 !5O_^.60 Kilpmot 

.Figure 1. Location map pf the major population centers and features* tnentioned 

in the text. 

this process in fhe Basin and Range is unknown. 

High chloride conceatrations are .an indication 

that more extensive inate.r-rock reaction has 

taken place, and this may infer longer flow 

paths and generally deeper circulation. Most 

high temperature geothermal wells in the-: Great 

FLftute I. DlK^ributi'on. of'Kar

out. The dilute Na-UCO, waters develop in areas 

where the rock contains appreciable sodium 

silicate or sodium aluminosilicate minerals and 

only small amounts of CO are available. 

Dilute to slightly saline Na-SO ( + Cl) 

waters occur principally in northeastern 

California and the adjacent part of Nevada 

(Fig. 4). High sulfate concentrations can 

result from dissolution of gypsum (anhydrite) in 

sedimentry rocks or dissolution of minerals such 

as alunite, jarosite, anhydrite, or pyrite from 

mineralized zones (Hem, 1970). Oxidation of 

sulfide to sulfate can also produce large 

sulfate concentrations and acid sulfate waters 

N,l1B.,/l»CI-ni,-:il C.ni,.,:^! t Ion of S..|tret,;(1 T1i.,r«.il W,itorii of tiw Horchcrn Hiisln iin-i \Linê—cunttou.',!. 

ICioi-t.iii r.it i IndlCHte itfl il;ili).| 

Conty 

ini Unii. i4prs> on the Carson [Uver 

SEHIiSK, sec, 14. T, II H., R, 20 P.. 

Itno, !t|>rs. on the Cirson River 

KWSU. sec. lb, T, 11 »,, R, 20 t. 

I.j*ascn County 

Anarfve Hot Springs 

KKSli. __. on. T. 28 N. R, 16 E. 

Ba.^stftt Hot Springs 

NUSe, sec. 12, T. 18 H., R. 7 t. 

Kel litg Hot Springs 

SUSt:, sec. 15. T, in a., R. 8 E. 

Uetidell Hot Springs 

HCb'U, sec, 21, T. 29 H., R, IS E. 

Zambonl Hoc Spring 

«WHU, sec. 24, T. 24 «.. R, 17 E, 

llodoc County 

Hoc Springs Hotel 

MESU. sec. 06. T, 42 «.,R, 17 E, 

Kelly Hot Springs 

HKNV. sec. 29, T, 42 H, R, in E, 

LcooArJs Hot Springs 

W.ue., sec, n, T. 4) N, R, 16 E. 

Llctle Hoc Springs 

NWSU, sec. 9. T. 19 K., I. 5 E, 

Seyforch Hoc Springs 

NUMV. sec. 12. T, 39 N , R, J E. 

West Valley Reservoir (spring) 

NWNE, sec, 29, T, 19 M,, R, 14 E 

Motio County 

Benton Hot Springs 

SU. sec. 2, T, 2 S.. R, Jl E, 

Fales Hot Springs 

SE, sec. 24, T, 6 N.. R, 2t E, 

Long Valley-Hot Creek Gorge 

NE, sec, 25. T. IS.. R. 28 E. 

Mono Lake - North Shore 

sec. II. T, 2 N.. R. 26 E, 

' South Shore 

sec, 18, T, IN,, R. 27 E. 

Travertine Hot Spring 

SU. soc. 34. T. 5 N.. R. 25 E, 

Ueor l„tke Ih.t Spring 

SU, sec. 11, T, 15 S., R, 44 

Ctssl.i Cuunty 

URCE-1 

sec, 23. T. 15 S., R, 26 E, 

Ir.tiiklln County 

Maple Crowe Hot Springs 

NE, sec, I. T, 13 S,, R, 41 E. 

UaylotuJ Hot Springs 

NE. sec, 8. T. 5 S., R. 39 E, 

One id.. County 

Uoodrutf Hot Springs 

HE, sec, 10, T, 16 S., R. 36 E. 

«,61 

6,52 

96 8.36 

79 11.53 

78.4 8.63 

95.5 8,26 

41 9.37 

98 8.40 

91.5 8,08 

61.8 7,82 

75,7 7.59 

85 7.66 

77.3 7,79 

56.5 9.32 

61 6.55 

90 6,6 

66 7.68 

33 6.38 

69 6.73 

76 7.3 

77 7.0 

178 

I in 

85 

125 

36 

100 

110 

IIO 

87 

IIO 

130 

63 

114 

ISO 

76 

76 

125 

15 

16 

20 

41 

13 

120 

64 

1.4 

1.6 

6.5 

4.0 


KjRiti/Locit Ion 

T:ihlo 1. Clicniril Ompimi I loii of Selected Tlii.Tniiil U.-ttrK of thf Nr>rthvrn lUstn nnA IttnK*—-cont Imicrf. 

(Oinrentr^t Ions .iro In BR/L, ieaperrfturt;s arc In °C; tiodltira (Na) values folloirfed hy K represent 

suJitim pluB potiiijslum; dasliCB (-) Indlc.ite nn ilatjial 

NEVADA 

Cariiun City 

Carvon Hoc Springs, 

SEHt. (ICC. i, T. 15 N., R. 20 E. 

Ptnyun Hills Udl 

sec. 2^. T. ib a., R. 20 E. 

amrchlU County 

Dixie Valley Hoc Springs 

se. sec. S, T. 22 N., 8. 3S E. 

l)Ule Federal S2-I8 

NE. sec. 18. T. 2* «., B. 37 E. 

~ Brtfdy'« Hot Spring (well) 

SU. sec. 12. T. 22 N., R. 26 E. 

Eagle S«U Works Spring 

sec. 34. T. 22 N., R, 26 E. 

Soda Lakc-Upsal Hogback 

SW. sec. 28, T. 20 M., R. 28 E. 

Stlllwiicer Area 

SW, sec. 07, T. 19 N.. R. 31 E. 

Lee Hot Spririgs 

Unsurveycd (39*'l2'N b I 18°43'U) 

DotJUlas County 

Hobo Hoc Spring 

SeSt, sec. 23. T. 14 H.. R. 19 E. 

Saratoga Hot Springs 

SES€, sec. 23. T. 14 N-, R. 20 E. 

Uatley's Hot Spring 

NE. ftec. 22, T. 13 N.,fl 19 E. 

Nile Spring 

SW, sec. 30. T. 47 N., R. 70 e. 

Trout Creek Ranch Well 

NWMW. sec. 23, T. 46 H.. R. 69 t. 

San Jacinto Ranch Spring 

HUNW, sec. 23. T. 46 H., R. 64 E. 

Rdzl RancU Hoi. Spring 

MC. 29, T. 45 N.. R. 54 E. 

Mineral (Contact) Hot Springs 

sec. 16, T. 45 t*., R. 64 E. 

Wild Horse Hot Spring 

SESe, sec. 4, T. 43 N.. R. 55 E. 

Hot Creek Sprlngit 

HW, sec. 12, T. 28 H., R. 52 E. 

Hot Creek Springs 

NW, sec. 34, T. 43 H., R. 60 E. 

Dot Sulphur Spring 

HE. sec. 8, T. 41 N. , R. 52 E. 

Wine Cup Ranch Well 

.WNW, sec 25, T. 41 N., R. 64 E. 

Hot Uke 

KNW. sec. 25, T. 38 H., R. 46 E. 

Unnaaed spring on Rock Creek 

SWSW. sec. I.T. 39 N.. R. 47 E. 

Huaboldc Wells Area 

SE. sec. 20, T. 38 N.. R. 62 E. 

Hot Hole 

ME, sec. 21, T. 34 M., R. 55 E. 

Hoc Spring near C«rlln 

sec. 33. T. 33 N.. R. 52 E. 

Sulphur Hot Spring 

NU. Bcc. II, T. 31 M., R. 59 E. 

Smith Ranch (Unn. spr. - Ruby Harsh) 

NU, sec. 2.. T. 27 H.. R. 58 E. 

Ettmeralda County 

Alkali Springs 

NU, sec. 26. T. Ol S.. R. 4| E. 

Sliver Peak (Waterworks) Hot Springs 

SE.ficc. 15. T 02 S.. B. 39 E. 

Eureka County 

Beowaue 

SU, sec. 08, T.. 31 N., R. 48 e. 

Hue Springs Point 

NW, sec. II. T. 29 N., R. 48 E. 

Bruffey's (Mineral Hill) Hot Spring 

sec. 14, T. 27 H.. R. 52 E. 

Waltl Hoc Springs 

SU.sec. 33. T. Z4 N., R. 48 E. 

Shipley Hot Springs 

NESE, sec. 23. T. 24 N., R. 52 E. 

IClobe Hot Springs ftartholomie) 

SE, sec.28, T. 18 N., R. 50 E. 

72 

boiling 

- 

boiling 

96 

88 

46 

50 

62 

43 

43 

26 

41 

60 

54 

26 

9.3 

8.6 

8,6 

8.27 

932°C 

6.78 

«24''C 

7.86 

«42''C 

7.57 

7.4 

8.9 

9,0 

8,8 

37. 5 6,76 

92 

59 

18 

35 

60 

56 

79 

93 

65 

98 

54 

66 

72 

39 

54 

7.2 

8,3 

8.1 

7.4 

9.1 

7.2 

7,30 

7.32 

8.4 

7.2 

6,87 

6.5S 

7.21 

7.6 

8.53 

8,0 

7.18 

8.98 

6.63 

7,0 

6.47 

7.2 

9.25 

lis 

383 

164 

259 

160 

170 

180 

47 

20 

58 

31 

21 

18 

23 

83 

40 

20 

139 

165 

- 

57 

23 

110 

65 

70 

210 

50 

320 

67 

58 

68 

40 

85 

275 

45 

2.6 

3.2 

4.4 

32 

82 

108 

44 

2 

.02 190 6.3 6 133 126 III 16.3 Mariner and others, 1974 

.03 

,32 

2.1 

1.7 

.6 

385 

850 

839 

IOOO 

1480 

450 

36 

36 

48 

42 

26 

6 .7 125 U7 

172 - 160k 

10 .01 145 3.6 

40 

16 

25 

29 

48 

46 

62 

49 

29 

41 

1.6 

9.4 

78 

60 

60 

45 

46 

540 

53 

52 

56 

57 

1.0 

1.0 

1 

11,5 

5.7 

8.6 

7.7 

Naae/Uictt Ion 

Tablf I. Clioalt-al t4tiniti>.-. tenptirntures are In '^C; sodlisg (Nu) values followed by K represent 

SIKIIIM pluu i>ot.-iNNliua; dashes (-) indicate no data.I 

Curdifto Mercury Mine well 

SE, sec. 28. T. 47 N., R. 37 E. 

Hog Hot Springs 

SWNU, sec. 07, T. 46 H.. R. 28 E. 

Baltazor Hot Springs (well) 

KW, sec. 13, T. 46 N.. R. 28 E. 

Howard-Hut Springs 

KE. sec. 04, T. 44 H.. R. 31 E. 

Dyke Hot Springs 

SE. sec. 25, T. 43 N.. R. 30 E. 

Ttie Hot Springs 

HE, sec. 20. T. 4| M., R. 41 E. 

Soldier Headows Hot Springs 

sec. 23, T. 40 H., R. 24 E. 

Pinto Hot Springs 

ESe.sec. 17, T. 40 H., R. 28 E. 

Double Hoc Springs 

sec. 4. T. 36 K.. R. 26 E. 

Macfarlane's Rath House Spring 

NW, sec. 27. T. 37 H.. R. 29 E., 

Well 

SWSE. sec. 03, T. 37 H., R. 39 E. 

Holcond^ Area 

SE. sec. 29, T. 36 N.. R. 40 E. 

Hot Pot 

SU, sec. II. T. 35 N.. R. 43 E. 

Hot Spring Ranch (Tipton) 

SE, sec. 05, T. 33 H., R. 40 E. 

Lander County 

Buffalo Vailey Hot Springs 

SE. sec. 23, T. 28 N., R. 4| E. 

Hoc Springs Ranch (Vailey of the Moon) 

NE. sec. 23, T. 27 H., R. 43 E. 

South Solth Creek Valley 

NE, sec. 25. T. 17 N.. R. 39 E. 

Spencer Hot Springs 

SE, sec. 13, T. 17 H., R. 45 E. 

Unnaaed spring near Walci Hoc Springs 

Unsurvcyed 39°56.6'N by I16**40-8'W 

Lyon__County 

Hazen Area 

SW, sec. la, T. 20 H., B. 26 E. 

Wabuska Hot Springs 

SE. ««c. lb, T. 15 N.. R. 25 E. 

Hind's (Kevada) Hot Sprioga 

SE. sec. 16, T. 12 M., R. 23 E. 

Uedeil Springs 

SW, sec. 07, T. 12 H., R. 34 E. 

Nye County 

Olana s Punch Boul 

SE, sec. 22, T. 14 N,, R. 47 E, 

Darrough's Hot Spring 

sec. 08, T. II N.. R. 43 E. 

Hot Creek Ranch Springs 

sec. 29. T. oa N., R. 50 E. 

Upper Hoc Creek Ranch Springs 

NESE. sec. 29, T. 08 H., R. 50 E. 

Uann (Hanny Coat) Spring 

NUSW, sec. 20. T. 04 H., R. 50 E. 

PcrshlnR County 

Colado (wells) 

SE sec. 33. T. 28 N. 32 e. 

Kyle Hut Springs 

SU. sec. 01, T. 29 N., R. 36 E. 

Trego Area 

40° 46'N by 119° 7'U 

Leach Hot Springs 

SE, sec. 36, T. 32 H., R. 38 C. 

Htnboidt House (Rye Patch) 

SE. sec. 21, T. 31 N., R. 33 E. 

srt. well 

Sou Hot Springs 

SE. sec. 29. T. 26 N.. R. 38 E. 

Hydcr Hot Springs 

SW. sec. 28, T. 25 N.. R. 38 E. 

60 

54 

90 

56 

66 

58 

54 

93 

80 

75 

70 

74 

57 

85 

49 

73 

53 

86 

72 

64 

8b 

94 

61 

60 

59 

95 

63 

67 

61 

60 

77 

- 

9.05 

7.50 

9.2 

8.86 

8.0 

8.53 

7.14 

7.93 

6.61 

7.4 

6.53 

6.95 

8.36 

6.53 

- 

8.0 

7.72 

6.49 

6.51 

7.05 

B.06 

8.65 

7,83 

esCc 

7.14 

8.29 

8.0 

8.1 

8.1 

84. 5 7.93 

92 

77 

70 

78 

7.56 

e3B''c 

6.50 

7.4 

_ 

7.3 

6.77 

57 

57 

150 

85 

85 

55 

63 

150 

105 

82 

- 

66 

39 

125 

BO 

71 

40 

no 

77 

83 

150 

110 

52 

153 

46 

98 

135 

161 

60 

85 

ISO 

79 

135 

340 

162 

440 

64 

63 

36 

10 

3 

10 

.2 

1.8 

3.1 

14 

4.8 

43 

30 

33 

18 

16 

45 

43 

20 

4.8 

43 

66 

70 

39 

4.5 

13 

50 

51 

1.3 

33 

43 

IIO 

95 

11 

8.8 

43 

120 

90 

106 

41 

10 


T.ibU' I. CftL'iBlr;il Oiispiitii t Ion til Selected TluTnal Waters of the northern FUuIn and Rjnge—cont InitcH. 

lOKutontriillons ar^ In ng/L, teap

'' 

I 

riRure 3. Distribution of Sa-HCO waters in the northern Basin and Range 

Province. ' 

discharges sulfate as enriched in oxygen-18 as 

gypsum of marine origin (+15 o/oo). Either 

marine gypsum is not available in areas where 

thermal springs develop or, more likely, the 

oxygen isotopic composition of the sulfate is 

being or has been reset in high temperature 

thermal-environments such as the intrusion of 

the Sierra Nevada Batholith or the development 

of mineralized zones. Sulfate-rich waters in 

some areas, such as northeastern California, are 

very constant in chemical composition (Table 

1). The dissolved sulfate concentration in the 

water is apparently controlled by the solubility 

of a common mineral, probably hydrothermal 

anhydrite. 

Mixed anion waters commonly develop in 

areas where the predominant bedrock or depth of 

circulation is changing. For instance, the Namixed 

anion waters common in northwestern Nevada 

west and northwest of the Black Rock Desert, 

represent a transition zone where rock type and 

depth of circulation of the thermal waters is 

changing. Instead of deep circulation in 

Mesozoic marine strata, which is common to the 

east and southeast, shallower circulation in 

predominantly unaltered volcanic rocks of 

Cenozoic age is more prevalent. The supposition 

of shallower circulation is evidenced by cooler 

spring temperatures and lower geothermometer 

temperatures. Sulfate is a major anion only 

locally where faults intersect mineralized 

areas, probably in the Mesozoic rock. 

Many of the springs in the Basin and Range 

Province have been analyzed several times over 

the last 100 years. These analyses are always 

slightly different and it is not possible to 

determine how much of the variation is due to 

improved analytical techniques and how much to 

actual changes in the chemical composition with 

101 

• 

2S0 50 too 

JgO, l}0..iLjlo 

CCS 

Tonopoh 

•EI.. 


•EI, 

•_/ 

Sail \ 

Lska "l 

cm \ 

y 

Figure 4. Distribution of Na-SO waters in the northem Basin and Range 

Province. 

time. Cole (1982) demonstrated that the major 

constituents of Becks Hot Springs and Wasatch 

Hot Springs in Utah varied by as much as 15 % 

during a single year. This variation was caused 

by dilution on six and three month cycles. Longterm 

variations certainly occur in many hot 

springs but these have not been dociunented. 

Chemical Compositions of Gases 

Most thermal springs discharge gas along 

with the water at rates which range from low to 

high. Chemically these discharges include 

nitrogen and/or carbon dioxide with lesser 

amounts of argon, methane, hydrogen, helium, and 

hydrogen sulfide (Table 2). These gases 

probably originate from the atmosphere (N. and 

and Ar.), soil (CO ), radiogenic processes (He 

and Ar7, and metamorphic or volcanic processes 

(CO-). Ratios of nitrogen to argon range from 

137/1 to 33/1 although most have N /Ar ratios 

are near the SO/1 expected from an atmospheric 

source. Organic decay product nitrogen is 

present in at least one sample (Wedell Spring - 

N-/Ar = 131/1). Methane concentrations are low, 

indicating that breakdown of organic material is 

contributing relatively little at most springs. 

Hydrogen concentations are occasionally well 

above that expected from an atmospheric source 

and indicate that hydrogen is being generated at 

depth. Detectable OO.OOS %) hydrogen concentrations 

occur only where high temperature 

systems are indicated by geothermometry. Helium 

concentrations are more than an order of magnitude 

higher than expected from an atmospheric 

source in roost springs and are almost certainly 

due to radiogenic decay of uranium, thorium, 

and/or their daughter products. Carbon dioxide 

makes up 99% or raore of the gas phase in the 

CO -charged slightly to moderately saline Na- 

HCO ( + Cl) waters.


Table 2. CoioposltLons of gas discharging from thermal springs, fumaroles and wells In the 

Northern Basin and Range. 

CALIFORNIA 

[Compositions reported In volume XI 

Alpine County 

Unnaned Spr. E. Fk. 

of the Carson River 

(9/3/81) 

Lassen County 

Zatsbonl Hot Springs 

''Fumaroles'* occur along the west side of 

Dixie Valley, at Fumarole Butte near Baker Hot 

Springs in Utah, and at Mammoth Mountain and 

Casa Diablo in Long Valley, California (Berry 

and others, 1980). The fumaroles in Dixie 

Valley in Nevada discharge water vapor 

mixed with air (Mariner and Evans, unpublished 

data). The fumarole on Mammoth Mountain 

discharges mostly CO. with minor amounts of 

nitrogen and traces of hydrogen (Table 2). 

(Hiemically the gas discharged by the 

•'fumarole" is more like the gases discharged 

from hot springs in the Hot Creek Gorge part of 

Long Valley than a fumarole associated with a 

volcano (analysis of a fumarole on Mt. Hood is 

included in Table 2 for comparison). 

Chemical Geothermometers 

The primary use of chemical data in 

geothermal exploration has been to estimate the 

temperature of the deep thermal-aquifer associated 

with a hot spring. The most useful 

geothermometers for estimating aquifertemperatures 

are either the quartz geothermometer 

of Fournier and Rowe (1966), the 

Na-K-Ca geothermometer of Fournier and Truesdell 

(1973), or the Mg-corrected Na-K-Ca geothermometer 

of Fournier and Potter (1979). Other 

means of estimating aquifer-temperatures include 

the sulfate-water isotope geothermometer 

(McKenzie and Truesdell, 1977), the gas 

geothermometer (D'Amore and Panichi, 1980), the 

Na/K geothermometer (Fournier, 1979), and ina 

very few systems, the solubilities of minerals 

such as anhydrite (Sakai and Matsubaya, 1974) . 

Geothermometer temperatures based on the 

chemical composition of water discharged from 

hot springs and shallow wells are shown on Table 

3. The high temperature areas in the northern 

Basin and Range Province O150 C in Table 3) 

include: Long Valley, Seyferth Hot Springs, 

unnamed springs on the East Fork of the Carson 

River in California; Raft River, Idaho,' Baltazor 

Hot Springs, Beowawe, Great Boiling Springs, 

Hazen, Hot Springs Ranch (Tipton), Hot Sulphur 

Spings (Tuscarora), Humboldt House, Leach Hot 

Springs, Lee Hot Springs, Pinto Hot Springs, San 

Emidio Desert, Soda Lake-Upsal Hogback, 

Steamboat Springs, Stillwater and Sulphur Hot 

Springs in Nevada; Alvord Hot Springs, Crump, 

Hot Lake, Hunters Hot Springs, and Mickey Hot 

Springs in Oregon; and Roosevelt Hot Springs in 

Utah. By types of waters, 10 are Na-Cl, 8 are 

Na-HCO,, 4 are Na-mixed anion waters, and 3 are 

Na-SO. waters. " Successful" geothermal wells 

have been drilled at roughly half of the Na-Cl 

discharging springs but only at one of the 

Na-HCO- discharging springs (Table 4). 

''Successful'' high-temperature geothermal wells 

have not been drilled near any of the Na-mixed 

anion or Na-SO. springs. 

Plots of silica and Na-K-Ca (Fig.5 ) show 

generally good agreement, with relatively few 

large disparities. Arbitrarily, the quartz 

103 

o 

w 

250 

200 

ISO 

- 100 

SO 

- 

- 

• 

^ 

« 

"'6 

50 100 ISO 

l-No-K-Co 

A'. • 

ftgur. ^. CantMrlsoo of [eo^.t.tui*. ..tlut.d lio. '.HI, 

• 


geothermometer was used when the Na-K-Ca geothermometer 

indicated a temperature of 100 C 

or more, the chalcedony geothermometer was used 

when the Na-K-Ca geothermometer indicated a 

temperature of less than 100 C. The few large 

disparities occur where waters discharge from 

silicic tuffs, CO -charged waters, waters 

contaminated with high-chloride saline lake or 

playa waters, and dilute high-pH waters. 

Springs issuing from silicic tuffs such as Hot 

Creek Ranch Springs in Nye County, Nevada and 

CO»-charged water such as the water discharged 

by Travertine and Fales hot springs in 

California have higher temperatures estimated 

from the silica geothermometer than from the Na- 

K-Ca geothermometer. Silica is apparently being 

taken into solution faster than quartz or 

chalcedony can be precipitated, supersaturation 

with respect to quartz or chalcedony is 

maintained and the quartz (or chalcedony) 

geothermometer give excessively high subsurface 

temperature estimates. The magnesium corrected 

Na-K-Ca geothermometer in these waters generally 

gives estimated aquifer-temperatures within 

25 C of the measured spring temperature. High 

CO. concentrations generally require high 

teraperatures for generation, but these 

conditions may be very deep (Barnes and others, 

1978). Some of the Na-Cl waters issue near 

saline lakes or playas and may contain some 

admixed saline lake waters (Utah Hot Springs 

adjacent to Great Salt Lake is an example). 

Since the saline water contains almost no 

calcium or magnesium, abnormally high Na-K-Ca 

geothermometer temperatures are calculated. The 

Na/K geothermometer is no better since the 

proportion of Na to K in the saline water was 

controlled initially by reactions which included 

calcium. Finally, the dilute high-pH waters 

1 

• 

• 

•/ 

•

Mariner et. al. 

Table 3. Geotherraoraeter temperatures foe springs of the Northern Basin and Range. 

Name 

[All temperatures In °C.] 

CALIFORNIA 

Alpine Qjunty 

Unn. sprs. on the (^rson River 

Unn. sprs. on the Carson River 

Lassen County 

Amadee Hot Springs 

Bassect Hot Springs 

Kellog Hot Springs 

Wendell Hot Springs 

Zamboni Hot Springs 

Modoc County 

Hot Springs Motel 


Leonards Hot Springs 

Little Hot Springs 

Seyforth Hot Springs 

West Valley Reservoir 

Mono (bounty 



Long Valley-Hot Creek (kirge 

Mono Lake - Worth Shore 

- South Shore 

Travertine Hot Springs 

IDAHO 

Bear Lake County 

Bear Lake Hot Springs 

Unn. spring 

RRGE-1 

Cassia County 

Franklin Oaunty 

Maple Grove Hot Springs 

Wayland Hot Springs 

Oneida County 

Woodruff Hot Springs 

NEVADA 

Carson City 

Carson Hot Springs 

Pinyon Hills Well 

Churchill County 

Brady's Hot Spring (well) 

Dixie Valley Hot Springs 

Dixie Federal 52-18 

Eagle Salt Works Spring 

Lee Hot Springs 

Soda Lake-Upsal Hogback 

Stillwater Area 

Silica 

172 

1A6 

109 

86 

101 

150 

(65) 

110 

116 

143 

102 

143 

152 

40 

118 

161 

94 

126 

110 

55 

39 

159 

77 

125 

47 

Geothermometers 

Na-K-Ca SO4-H2O 

175 

140 

95 

62 

78 

121 

51 

96 

95 

124 

69 

129 

129 

79 

81 

191 

79 

28 

71 

73 

44 

171 

64 

105 

57 

insufficient data 


167 

145 

229 

198 

173 

165 

169 

104 

157 

144 

207 

- 

162 

161 

140 

200 

198 

205 

247 

684 

224 

173 

165 

127 

268 

282 

127 

177 

Measured 

Surface Depth 

84 

65 

96 

79 

78 

96 

41 

98 

92 

62 

79 

85 

77 

56 

61 

90 

66 

33 

69 

48 

42 

145 

76 

77 

27 

49 

46 

- 

72 

191 gas geot. 

- 

88 

100 

96 

122 

142 

188 

188 

178

Table 3. (ôthermometer temperatures for springs of the Northern Basin and Range - 

continued. 

[All temperatures in °C.) 

Name Silica 

Douglas County 

Hobo Hot Spring 

Saratoga Hot Springs 

Walley's Hot Spring 

Elko County 



Hot Hole 

Hot Lake 

Hot Spring near Carlin 

Hot Sulphur Spring 

Huraboldt Wells Area 

Mineral (Contact) Hot Springs 

Nile Spring 

Rizzi Ranch Hot Spring 

San Jacinto Ranch Spring 

Sulphur Hot Spring (Ruby Valley) 

Smith Ranch 

Trout Creek Ranch Well 

Unnamed spring (Rock Creek) 

Wild Horse Hot Spring 

Wine Cup Ranch Well 

Esmeralda County 

Alkali Springs 

Silver Peak (Waterworks) Hot Springs 

Eureka (iaunty 

Beowawe 

Bruffey's (Mineral Hill) Hot Spring 

Hot Springs Point 

Klobe Hot Springs 

Shipley Hot Springs 

Waltl Hot Springs 

Humboldt County 

Baltazor Hot Springs (well) 

Bog Hot Springs 

Ckirdero Mercury Mine well 

Doable Hot Springs 


Golconda Area 

Hot Pot 

Hot Spring Ranch (Tipton) 

Howard Hot Springs 

Macfarlane's Bath House Spring 


Soldier Meadows Hot Springs 

The Hot Springs 

Well 

69 

31 

80 

31 

132 

86 

79 

90 

167 

117 

127 

50 

37 

27 

183 

72 

33 

37 

61 

Inst 

Geotherraoraeters 

Na-K-Ca S0^-H20 

70 

- 

84 

17 

66 

85 

57 

75 

183 

34 

129 

43 

71 

44 

181 

71 

69 

69 

73 

fficlent data 


140 142 

196 

80 

87 

69 

61 

88 

161 

65 

108 

140 

128 

86 

S9 

150 

71 

99 

161 

84 

77 

- 

Lander Ctounty 

Buffalo Valley Hot springs 

119 

Hot Springs Ranch(Valley of the Moon) 61 

South Smith Creek Valley 

143 

Spencer Hot Springs 

95 

Unn. spring near Walti Hot Spring 127 

194 

64 

36 

72 

48 

78 

148 

88 

- 

126 

137 

92 

81 

162 

80 

71 

176 

64 

54 

81 

126 

51 

156 

95 

129 

105 

175 

161 

251 

158 

207 

140 

143 

Measured 

Surface Depth 

46 

50 

62 

26 

37 

56 

18 

79 

92 117 

60 

60 

43 

41 

_ 

93 

65 

43 

35 

54 

59 

60 

40 

98 201 

66 

54 

54 

39 

72 

90 

54 

60 

80 

66 

74 

57 

85 

56 

75 

93 

54 

58 

70 

73 

53 

86 

72 

64 

Mariner et al.


Table 3. Geotherraometer temperatures for sprlngsl of the Northern Basin and Range 

continued. 

Name 

(All temperatures in °C.) 

Lyon County 

Hazen Area 

Hind's (Nevada) Hot Springs 


Wedell Springs 

Nye (ûnty 

Darrough's Hot Spring 

Diana's Punch Bowl 

Hot Creek Ranch Springs 

Upper Hot Creek Ranch Springs 

Warm (Nanny (kiat) Spring 

Pershing County 

Colado 

Humboldt House (Rye Patch Reserv.) 

- artesian well 

Hyder Hot Springs 

Kyle Hot Springs 


Sou Hot Springs 

Trego Area 

Washoe County 

Bowers Mansion Hot Springs 

Fly Ranch (Ward's) 

Great Boiling Spring 

Lawton Hot Springs 

Moana Springs Area (Biglin well) 

San Emidio Desert 

Steamboat Springs 

The Needle Rocks 

White Pine Oaunty 

Cherry Creek Hot Springs 

Monte Neva Hot Springs 

OREGON 

Harney County 

Alvord (Indian) Hot Springs 

Crane Hot Springs 

Mickey Hot Springs 

Trout Creek Hot Springs 

Unn. spr. near Hot Lake 

Unn. spr. near Harney Lake 

Lake Cbunty 

Barry Ranch Hot Springs 

Crump 

Fisher Hot Springs 

Hunters Hot Springs 

Suramer Lake Hot Springs 

UTAH 

Beaver Oaunty 

Roosevelt Seep 

Roosevelt Steam Well 

Thermo Hot Springs 

(ô thermometers 

Silica Na-K-Ca SO^-HjO 

161 

74 

143 

162 

136 

67 

130 

143 

81 

128 

219 

166 

84 

137 

155 

85 

124 

38 

126 

167 

84 

114 

185 

201 

143 

114 

74 

152 

124 

185 

140 

165 

133 

152 

172 

123 

157 

107 

167 

238 

144 

106 

166 

86 

146 

139 

126 

80 

62 

36 

29 

169 

252 

238 

70 

81 

176 

84 

124 

45 

105 

205 

145 

98 

189 

207 

214 

90 

60 

157 

124 

197 

143 

176 

105 

139 

173 

123 

143 

112 

142 

234Na-K 

120 

220 

140 

176 

154 

176 

93 

207-220 

231 

273 

235 

231 

202 

158 

189 

216 

278 

142 

Measured 

Surface Depth 

86 

61 

94 

60 

95 

59 

63 

67 

61 

61 

- 

77 

78 

77 

92 

70 

84 

46 

80 

86 

49 

85 

89 

94 

56 

61 

79 

78 

78 

86 

52 

96 

68 

88 

78 

68 

96 

43 

25 

208 

90 

lOB 

129 

155 

156 

126 

115 

208 

208

Table 3. (feotherraometer teraperatures for springs of the Northern Basin and Range 

continued. 

Name 

[All teraperatures In °C.] 

Box Elder County 

Crystal (Madsen's) Hot Springs 

Udy Hot Springs 

Juab County 

Baker Hot Springs 

Millard County 

Meadow Hot Springs 

Salt Lake County 

Beck's Hot Springs 

Toole County 

Wilson Hot Springs 

Weber County 

Ogden Hot Springs 

Utah Hot Springs 

Geotherraoraeters Measured 

Silica Na-K-Ca SO^-HjO Surface Depth 

42 

42 

86 

69 

84 

68 

91 

63 

51 82 

52 

104 

90 

60 

218 

219 

Table 4. Geothermal Systems with Estiraated Reservoir-Temperatures >150°C 

Na-HCOj Waters 

*Beowawe 

Hot Springs Ranch 

Hot Sulphur Springs 

(Tuscarora) 


Long Valley 

Mickey Hot Springs 


Sulphur Hot Springs 

(Ruby Valley) 

Na-Mixed Anion Waters 

Alvord Hot Springs 

Hot Lake (Alvord Desert) 


Unn. Springs-Carson River 

Na-SO^ Waters 

Baltazar Hot Springs 


Seyferth Hot Springs 

•Locations of "successful" geothermal wells. 

such as Zamboni or Benton hot springs which 

discharge from granites near the contact of the 

Basin and Range with the Sierra Nevada contain 

unusually large silica concentr-ations due to 

dissociation of silicic acid (H.SiO. to H.SiO.and 

fl.SiO.=). With one of the computer codes 

such as SOLMINEQ (Kharaka and Mariner, 1977) the 

temperature at which the thermal water is in 

equilibrium with chalcedony or quartz, as 

appropriate, can be determined. These values 

are enclosed in parentheses in Table 3. 

107 

22 

56 

43 

85 

41 

56 

61 

56 

57 

Na-Cl Waters 

Miiriner et al. 

Crump 

Great Boiling Spring 

Hazen 

*Huraboldt House 

*Raft River 

•Roosevelt 

San Emidio Desert 

*Soda Lake-Upsal Hogback 

•Stearaboat Springs 

•Stillwater 

The apparent agreement between the 

temperatures estimated from the silica and 

cation geothermometers in most waters of the 

Great Basin could be fortuitous. A more 

important question is, how do the estimated 

temperatures compare with measured temperatures 

in geothermal wells? Deep—well temperature data 

are available for only 15 systems (Table 5). 

Surprisingly, when measured and estimated 

temperatures are compared for all IS, the 

measured temperatures are, on the average, 

only 14 C cooler than the estimated temperatures. 

The standard deviation is however.


Table 5. Expected and Measured Temperatures of Geothermal Systems 

in the Northern Basin and Range. 

Name 

High Discharge Springs 

Beowawe 

Hot Sulfur Springs (Tuscarora) 


Long Valley 


Wendel Hot Springs 

Low Discharge Springs 

Humboldt House 

Roosevelt Hot Springs 

San Eraidio Desert 

Wells 

Brady's Hot Springs 

Colado 

Raft River 

Soda Lake 

Stillwater 

Wabuska 

Teraperatures 

Expected^ Measured 

214 

175 

167 

196 

205 

136 

184 

175 

187 

162 

148 

161 

151 

162 

143 

•Average of ^silica, ^cation, and '•S0^-H20 when available. 

rather large ( + 28 C). The estimated 

temperature for each system is an average which 

includes values from the quartz or chalcedony 

geothermometer, as appropriate, the Na-K-Ca 

geothermometer, and when available, the SO.-ILO 

isotope geothermometer. Surprisingly, the 

average difference between expected temperatures 

calculated from geothermometry and the measured 

temperatures for low discharge rate (

thermal water discharging at Leach if yoUgSssume 

that the small oxygen shift (+0.3 o/oo 6 0) 

observed in the cold spring water is due to 

nonequilibrium evaporation (Fig. 6). This 

evaporation could have taken place prior to 

recharge, or in an unconfined aquifer. Although 

Mt. Tobin is the highest mountain in the region, 

and could be the recharge area for Leach Hot 

Springs, this interpretation forces the data to 

the limits of credibility, only a small snsmiit 

area on Mt. Tobin exists as a catchment basin 

and, most damaging, two travertine depositing 

springs, Buffalo Valley Hot Springs east of Mt. 

Tobin and Hyder Hot Springs in Dixie Valley 

south of Mt. Tobin are even more depleted in 

deuterium (-132 per mil and -133 per mil, 

respectively). 

-no 

-120 

-130 

_ 

_ 

- 

- / 

/ • 

*x 

/ 

1 

/ 

L*act« H» 

/ 

S»>l


Table 6. Isotopic data for thermal 

Range. 

CALIFORNIA 

NEVADA 

Alpine Qjunty 

Unn. sprs. E.Fk. Carson River 

(84°C spring) 

(65°C spring) 

Lassen County 

Amadee Hot Springs 

Bassett Hot Springs 

Kellog Hot Springs 

Wendell Hot Springs 

Zamboni Hot Springs 

Modoc County 

Lake City Mud Eruption 


Little Valley Hot Springs 

Hot Springs Motel (well) 

Menlo Hot Springs 

Seyforth 

Mono (ûnty 



Long Valley (Hot Creek (kirge) 

- LDMW 

Mono Lake - North Shore 

- South Shore 


Travertine Hot Springs 

Churchill County 

Brady's Hot Spring (well) 

Dixie Federal 52-18 

Dixie Valley Hot Springs 

- LDMW 


Stillwater Area (well) 

Douglas C>3unty 

Walley s Hot Springs 

Elko County 

Hot Creek 

- LDMW 


- LDMW 

Hot Hole 

Hot spring near Carlin 

Hot Sulfur Spring (Tuscarora) 

Humboldt Wells 

- LDMW 

Mineral (Contact) Hot Spring 

Nile Spring 

Sraith Ranch Hot Spring 

Sulphur Hot Spring (Ruby V.) 

- LDMW 

Sulphur Hot Spring (Elko) 

no 

springs of the northern Basin and 

del D del 180 

126.5 

125.3 

120.0 

115.1 

115.5 

120.8 

118.1 

113.0 

115.1 

116.9 

117.0 

112.3 

121.2 

135.5 

132.8 

120.3 

115 to -13C 

126.6 

126.9 

137.3 

139.3 

-121.2 

-133.9 

-126.1 

-120.0 

-125.8 

-110.0 

-119.5 

-126.7 

-121.4 

-135.7 

-128.9 

-144.7 

-132.7 

-138.6 

-134.7 

-122.1 

-139.0 

-139.1 

-132.8 

-130.1 

-124.6 

-145.9 

-15.56 

-15.54 

. 

-13.54 

-14.09 

-14.04 

-15.34 

-14.79 

-13.54 

-14.20 

-13.81 

-15.30 

-14.05 

-17.46 

-17.46 

-14.83 

-16.91 

-15.69 

-16.29 

-16.64 

-14.22 

-14.72 

-15.89 

-15.22 

-13.34 

-12.36 

-15.55 

-16.28 

-15.69 

-17.40 

-16.20 

-15.31 

-16.64 

-16.65 

-15.81 

-17.61 

-18.24 

-16.24 

-16.09 

-16.87 

-17.67

• 

Table 6. Isotopic data for thermal s 

Range—continued. 

Esmeralda County 

Silver. Peak (Water Works spr.) 

Eureka County 

Beowawe 

Hot Springs Point 

Klobe Hot Springs 

Waltl Hot Springs 

Humboldt (>Junty 

Baltazor Hot Springs 

Bog Hot Springs 

Double Hot Springs 


Hot Pot 

Hot Springs Ranch (Tipton) 

Howard Hot Spring 

Macfarlanes Hot Springs 


Soldier Meadows Hot Springs 


Lander County 

Buffalo Valley Hot Springs 

- LDMW 

Hot Springs Ranch 

(Valley of the Moon) 

Sraith Creek Valley 

Spencer Hot Spring 

Unn. Spr. (Grass V. nr Waltl) 

Lyon Ckjunty 

Hazen Area 

Hinds (Nevada) Hot Springs 


Wedell 

Mineral County 

Soda Springs 

Nye County 

Diana's Punchbowl 

Darroughs Hot Springs 

Pershing County 

Colado 

Hyder Hot Springs 

Humboldt House - deep well 

- shallow well 

- LDMW 

Kyle Hot Springs 

- LDMW 


Summit Spring - LDMW 

Trego Hot Springs 

111 

prings of the northern Basin and 

del D 

-118.2 

-130.0 

-136.1 

-127.9 

-129.8 

-125.3 

-124.3 

-128.8 

-128.0 

-136.7 

-131.4 

-127.1 

-127.2 

-129.2 

-129.2 

-134.6 

-131.6 

-135.2 

-117.3 

-127.8 

-130.4 

-135.8 

-134.8 

-121.5 

-123.2 

-129.7 

-131.9 

-130.3 

-124.9 

-122.5 

-125.5 

-133.2 

-130.6 

-127.2 

-119.9 

-130.0 

-121.1 

-128.6 

-126.8 

-124.5 

del 180 

-13.50 

-14.76 

-15.97 

-16.28 

-16.87 

-15.26 

-15.30 

-15.93 

-16.29 

-16.70 

-15.74 

-16.17 

-12.54 

-14.48 

-16.56 

-16.44 

-15.85 

-13.61 

-14.95 

-16.28 

-16.68 

-16.01 

-16.73 

-13.30 

-16.01 

-15.38 

-15.90 

-16.13 

-16.24 

-15.50 

-14.01 

-15.66 

-14.64 

-14.09 

-15.-25 

-15.50 

-14.71 

-15.70 

-16.80 

-14.40 

Mariner 

et al. 

., --....,-


Table 6. Isotopic data for thermal springs ,of the northern Basin a'nd 

Range—con t inued. 

Washoe Ciounty 

Bowers Mansion Hot Springs 

Fly Ranch 

Qreat Boiling Springs- 

San Eraidio Desert 


The Needle Rock's 

White Pine (kiuncy 

Cherry Creek Hot Springs 

Monte Neva Hot Springs 

del D del 180 

-102-.3 

-120-7 

-100.5 

-10*8.3 

-116.7 

•^106; 5 

-127.8 

-i;27.8. 

OREGON 

Harney County 

Alvord (Indian) Hot Springs' -123.6 

Graiie Hoc Springs -133.3 

Hlickey Hot Springs -124*3 

Kike Creek - LDMW -108.4 

Trout Creek Hot Spring- -127.4 

Trout Creek- LDMW " -115.3 

Unn.. Sprs. near Hot Lake -125.4 

Unn. H. Sprs near Harney take -128.5 

Lake County 

Barry Ranch Hot Springs 

Crane Creek-.LDMW 

Crump 

Deep Greek - LDMW 

Fisher Hot Springs 


Summer Lake Hot Springs 

Malheur County 

Unn. Spr. nr. McDermltt 

UTAH 

Beaver Co linty 

Roosevelt Seep 


.Steam Weil at Roosevelt H.S. 

-119.4 

-1.0U2 

-115.5 

-10'6i6 

-117.0 

-119.0 

-115.0 

•134,6 

-M3-, 

-118. 

-115, 

-14.79 

-14.72 

-10.83 

-12,05 

-12.16 

- 6.33 

-16.20, 

-16.68' 

-13.23 

-16.17 

-13.42 

-14.05 

-16;17 

-15.50 

-14.36 

-13.72' 

-13.40 

-13.,28 

-13.46 

-14.32: 

-13i32 

-16.951 

-12.95 

-14.3.2 

-12-99 

Juab County 

Grater (Baker,Abraham) Hot S. -126.3 -16.0 

changes due to exchange with minerals in the 

confining rock (Craig, 1963). In the northern 

Great Basin, dilute Na-HCO, waters and Na-SO. 

waters generally "have less oxygen enrichment 

than Na-Cl waters (Figs, 8, 9, and 1(>) . 

Bicarbona^te—rich waters,, however, occasionally 

have very large oxygen shifts lap to 4 o/ooJ 

Fig:. 8). Carbonates 'in linietsoBes are 

usually -t^lO tb +30 per mil in 6 6 while 

silicates in most igneous rocks range from -t-5 to 

+15 6/oo. Larger oxygen shifts are observed in 

water associated with limestones, than in waters 

1.12 

associated with silicate rocks because of the 

concentration difference and the faster exchange 

rates between carbonates and waters. Tlie lack 

of cortelatioii between oxygen shift and amount 

of dissolved solids in the Na-Cl waters is an 

indication that although these waters generally 

occur where most wa'ter-roct. reaction has taken 

place, the chloride concentration is at least, 

in part, a function of chloride availability. 

ITie oxygen isotopic compositions of a few 

sulfates in thermai waters of the Basin and 

5' 

I 

t'l

5 - 

4- 

^^- 

>> 

S2 

^ 3 

• • •• 

•• • • 

t 

I 

10 20 30 40 50 60 70 

Meq. cations 

Figure 8. Oxygen shift of HCO -rich thermal water as a function of mllllequivalents cations (specific 

conductivity). 

I - 

• A 

tt 

.A A 

I 0 20 30 40 50 60 70 

Meq. cations 

Figure 9. Oxygen shift cf SO^-rlch thermal waters as a function of mllllequivalents cations (specific 

conductivity). 

113 

Mariner et al.


9 

K 

O 


10 20 30 40 50 60 70 

Meq. cations 

Oxygen .shift of Cl-rlch thennal waters as a function of mill icquivolents cations (specific 

conductivity), 

Range Province have been reported by Nehring and 

Mariner (1979) . Chir intent was to estimate the 

thermal-aquifer temperature using the sulfatewater 

isotope geothermometer. of McKenzie and 

Truesdell (1977). The sulfate-water isotope 

geothermometer generally gives calculated 

temperatures that are slightly hotter than 

those obtained from the quartz or Na-K-Ca 

geothermometers. However, in some areas, the 

sulfate-water isotope geothermometer gives 

temperatures considerably lower than the 

measured surface temperatures or considerably 

higher than the temperatures estimated from the 

other geothermometers (Table 3). It is possible 

for sulfate to be dissolved from tbe country 

rock after tbe thermal fluid leaves the thermal 

aquifer or the thermal fluid raay mix with 

sulfate-rich nonthermal water before it 

discharges at the surface. This added sulfate 

probably will have a different original isotopic 

composition and could significantly change the 

isotopic composition of the total sulfate in the 

discharge. 

In the northern Basin and Range Province, 

the sulfate-vater isotope geotherraometer 

indicates aquifer-temperatures which are 

generally 50 to 100 C higher than those estimated 

from the silica or cation geothermometers. 

A possible explanation for these 

higher apparent temperatures is that the 

depleted sulfate is from dissolution of minerals 

formed during previous high temperature 

114 

hydrothermal or metamorphic events. However, 

these minerals must be situated along the flow 

path from the reservoir to the surface or the 

residence times of fluids in the thermal 

reservoir must be very short. The latter 

possibility does not appear likely due to the 

old apparent age of most of the waters. 

However, in mineralized areas, there is the 

possibility of dissolving isotopically depleted 

sulfate which does not have enough time to 

attain equilibrium with the dissolving fluid. 

For example, pickeringite (ideal formula 

MgAl,(SO.). 22H,0) from a site near Lahontan 

Reservoir west of Fallon was -6.53 o/oo 8 0. 

Dissolution of such a raineral without 

concomitant reequilibratlon would result in 

excessively high apparent SO .-HO isotopic 

equilibrium temperatures. Sulfate minerals are 

often associated with ore deposits in western 

Nevada and so isotopically depleted sulfate is 

readily available. 

Alternatively, although the sulfate-water 

isotope temperatures are no closer to the 

measured teraperatures in the deep wells then the 

temperatures calculated from the cation or 

silica geothermometers, the apparent sulfatewater 

equilibrium temperatures could be 

correct. Calculations with the computer code 

SOLMNEQ (Kharaka and Barnes, 1973, as modified 

by Kharaka and Mariner, 1977) indicate 

saturation with respect to anhydrite (CaSO.) at 

temperatures near those estimated from the

ulfate—water isotope geothermometer in several 

f the systems in northeastern California (Table 

) . This may be an indication that the 

emperatures calculated from the sulfate-water 

sotope geothermometer are accurate in this 

rea. The cooler teraperatures estimated from 

he quartz and Na-K-Ca geothermometer may 

ndicate that chemical equilibrium was 

pproached in a shallow aquifer at temperatures 

ear the spring temperature but the isotopic 

omposition remained unchanged. Anhydrite 

aturation temperatures (Table 7) for Travertine 

ot Springs, Hot Lake (Oregon), Stillwater, Soda 

ake-Dpsal Hogback, Hazen and Alvord Hot Springs 

re also reasonably near the sulfate-water isoope 

equilibrium temperatures. The differences 

n temperatures estimated from theoretical 

nhydrite saturation (175 C) and sulfate-water 

sotopic data (127°C) at the Soda Lake-Upsal 

ogback area may indicate that reequilibratlon 

r mixing has taken place in a shallow aquifer 

ince deep wells have encountered temperatures 

ore than SO C hotter. Lee Hot Springs, located 

onth of Fallon, has an apparent anhydrite 

aturation temperature of only 173 C, almost 

00 C cooler than the sulfate-water isotopic 

qnillbrium temperature. The sulfate at Lee 

ust be from a near surface hydrothermal mineral 

ource. At the other extreme, Abraham Hot 

prings in Utah had a sulfate-water isotopic 

quilibrium temperature less than the measured 

pring temperature. Apparently, the sulfate 


discharged at Abraham Hot Springs is of marine 

origin (initially about +15 o/oo in 6 0) and 

it never attained, isotopic equilibrium with the 

thermal water. 

Summary 

Thermal waters in tbe Basin and Range 

Province range from dilute Na-HCO,and Ca-HCOj 

waters to very saline Na-Cl waters. The 

most saline Na-Cl waters occur near Great Salt 

Lake or near the sinks and playas of 

northwestern Nevada. Slightly saline CO,charged 

Na-HCO, waters are common near the 

Sierra Nevada. Na-SO ( + Cl) waters occur in 

northeastern California and western Nevada. 

Sulfate in these waters may be from sulfate 

minerals, initially deposited during previous 

hydrothermal events. 

Meteoric waters in the probable recharge 

areas for most hot springs in the Northern Basin 

and Range Province are generally not as depleted 

in deuterium as the waters currently discharged 

by the hot springs. This difference is largest 

for waters associated with travertine and is 

almost certainly an indication that the thermal 

waters recharged during times of colder climate, 

probably the Pleistocene. 

Measured temperatures in deep wells are, on 

the average, 14 C cooler than expected from the 

chemical geothermometry on waters from nearby 

Table 7. Anhydrite saturation teraperatures and sulfate-water Isotope 

equilibrium teraperatures for thermal waters of the northern 

Basin and Range. 

Name of Sample Anhydrite Saturation T - S04-H20 

California 

Fales Hot Springs 310 

Hot Springs Motel (Surprise Valley) 211 

Kelly Hot Springs 193 

Seyferth Hot Springs 189 

Travertine Hot Springs 190 

West Valley Reservoir (Hot Spring) 220 

Nevada 

Hazen (Hot Springs) 


Soda Lake - Upsal Hogback (well) 

Stillwater (well) 

Wabuska (shallow well) 

185 

173 

125 

180 

176 

Oregon 

Alvord Hot Springs 275 

Spring near Hot Lake (Alvord Desert) 215 

Utah 

Abraham (Baker) Hot Springs 


115 

159 

172 

184 

200 

198 

205 

173 

247 

220 

282 

127 

177 

140 

231 

230 

22 

142

Mariner, et al. 

hot springs and shallow wells. The measured 

temperatures in the geotbermal reservoirs are, 

on the average, 22 C cooler than expected when 

spring waters are used to estimate the deep 

aquifer-temperature, however measured 

temperature are only 2 C lower than expected 

when waters from shallow wells are used to 

estimate the temperature of the deep aquifer. 

Anhydrite saturation temperatures are 

similar to sulfate-water isotope equilibrium 

teraperatures for the more saline thermal waters 

of the northern Basin and Range Province. 

However, some systems in northeastern California 

have aquifer-temperatures of 200 to 220 C based 

on anhydrite saturation and SO,-H_0 isotopic 

equilibrium temperatures. These temperatures 

are roughly 100 C above the temperatures 

estimated from silica or Na-K-Ca 

geothermometers. 

The oxygen-18 enrichment of Na-HCO, thermal 

waters generally increases as the total 

dissolved solids increase. Concentrations of 

dissolved solids in Na-Cl waters generally are 

higher than either Na-HCO, or Na-SO. waters. 

Although Na-Cl waters are generally more 

enriched in oxygen—18, no correlation seems to 

exist between their oxygen-18 enrichment and 

amount of dissolved solids. 

RP.FF.RENCES 

Adams, W. B., 1944, Chemical analysis of 

nnnicipal water supplies, bottled mineral 

waters and hot springs, Nevada: Nevada 

University, Reno, Department of Food and 

Drugs, Public Services Division, 16 p. 

Banwell, C. J., 1963, Oxygen and hydrogen 

isotopes in New Zealand thermal 

areas. In Tongiorgi, E., ed.. Nuclear 

Geology on Geothermal Areas: National 

Research Council, Laboratory of Nuclear 

Geology, Pisa, p. 95-138. 

Barnes, Ivan, Irwin, W. P., and White, D. E., 

1978, Global distribution of carbon 

dioxide and major zones of seismicity: 

U.S, Geological Survey, Water- 

Resources Investigations 78-38, 12 p. 

Bateman, R, L. and Scheibach, R. B., 1975, 

Evaluation of geothermal activity 

in the Truckee Meadows, Washoe County, 

Nevada: Nevada Bureau of Mines 

and Geology, Report 25, 38 p. 

Benoit, W. R., 1978, The discovery and geology 

of the Desert Peak, Nevada, geothermal 

field, in Energy exploration and politics: 

California Division of Oil and Gas, 11 p. 

Berry, G. W., Grim, P. J. and Ikelman. J. A.. 

compilers, 1980. Thermal springs list 

for the United States: National Oceanic 

116 

and Atmospheric Administration key'to 

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BOREHOLE GEOPHYSICAL TECHHIQUES FOR DEFINING PERMEABLE ZONES 

IN GEOTHERNAL SYSTEHS 

ABSTRACT 

Borehole electrical geophysical methods have 

considerable potential for helping to define hot 

and permeable zones in geothermal systems. Borehole 

geophysics differs from geophysical well 

logging and has a much greater area of search 

around a borehole. Very little developmental work 

has taken place in borehole electrical methods to 

date. At UURI, we have been developing computer 

methods to model various electrical arrays for 

borehole configurations. We plan to compare, the 

several possible survey methods and then design a 

field system based on the method that appears from 

the computer studies to be optimum. 

From our studies to date we tentatively 

conclude that the cross-borehole method produces 

larger anomalies than does the single-borehole 

method; cross-borehole anomalies using a pole-pole 

array are smaller than those for a dipole-.dipole 

array; the cross-borehole mise-a-la-masse method 

produces larger anomalies than does other crossborehole 

methods; and, the anomalies due to a thin 

structure are generally much smaller than those 

for a sphere, as is to be expected. 

INTRODUCTION 

The key problem worldwide in development of 

hydrothermal resources appears to be more in 

locating permeable zones than in locating high 

temperatures. Grindly and Browne (1976) note that 

of 11 hydrothermal fields investigated in New Zealand, 

all of which have high temperatures (230°C 

to 300°C), five are non-productive chiefly because 

of low penneability. Three of the eleven fields 

are in production (Wairakei, Kawerau and Broadlands) 

and in each of these fields permeability 

limits production more than temperature does. Hot 

but unproductive holes have been drilled at many 

of the major geothermal areas in the world, 

including The Geysers, Roosevelt Hot Springs, 

Coso, and Meager Creek, to name a few. 

Permeability can be primary or secondary. 

Primary permeability in clastic rocks originates 

from int.ergranular porosity and it generally 

decreases with depth due to compaction and cementation. 

In volcanic sequences, primary intergranular 

porosity and permeability exist, but greater 

permeability exists in open spaces at flow contacts 

and within the flows themselves. Primary 

permeability in crystalline igneous rocks is 

generally very low. Secondary permeability occurs 

in all rock types in open fault zones, fractures 

Phillip M. Wright and Stanley H. Ward 

Earth Science Laboratory 

University of Utah Researcli' Institute 

391 Chipeta Way. Suite C 

Salt Lake City, Utah 84108 

147 

and fracture intersections, along dikes and in 

breccia zones (Brace, 1968; Moore et al., 1985). 

Changes in permeability come about through mineral 

deposition in open spaces or by leaching by the 

thermal fluids. 

Although none of the geophysical methods maps 

permeability directly, any geological, geochemical 

, or hydrological understanding of the factors 

that control the penneability in a geothermal reservoir 

can be used to help determine geophysical 

methods potentially useful for detecting the 

boundaries and more permeable parts of a hydrothermal 

system. At UURI, we have been developing 

electrical borehole techniques to detect and map 

permeable zones in the subsurface, especially 

fractures. 

BACKGROUND—BOREHOLE GEOPHYSICS 

It is important to understand the differences 

between geophysical well logging and borehole geophysics. 

In geophysical well logging, the instruments 

are deployed in a single well in a tool or 

sonde, and the depth of investigation is usually 

limited to the first few meters from the wellbore. 

Well-logging techniques have been developed 

by the petroleum industry over a period of half a 

century and have been applied with variable success 

by the geothermal industry. The major adaptations 

to the geothermal environment are the 

requirements of high temperature tools and the 

different interpretation required for hard rock 

(volcanic, igneous) lithologies. Other differences 

include a strong emphasis in geothermal 

exploration on fracture identification and the 

effects of hydrothermal alteration upon certain 

log responses. Much research remains to be done 

in order to understand fully the responses of 

various well logs in geothermal reservoirs and 

their typically fractured, altered, commonly 

igneous and metamorphic host rocks. In spite of 

the relative lack of knowledge of well-log 

response in geothermal reservoirs, several logs or 

log combinations have been used successfully to 

investigate such properties as lithology, alteration, 

fracturing, density, porosity, fluid flow 

and sulfide content, all of which may be critical 

in deciding how and in what intervals to complete, 

case, cement or stimulate a well (Glenn and Hulen, 

1979; Keys and Sullivan, 1979; Sanyal et al., 

1980; Glenn and Ross, 1982; Halfman et al., 1982). 

By contrast, borehole geophysics refers to 

those geophysical techniques where energy sources 

and sensors are deployed (1) at wide spacing in a

w- \''" • ' 

'' .,si"hgle borehole, (2) partly in one borehole and 

partly on the surface, or (3) partly in one borehole 

and partly in a second borehole. Thus, we 

speak of borehole-to-surface, surface-to-borehole 

aiid borehole-to-borehole surveys. The depth of 

investigation is generally much greater in borehole 

geophysical surveys than it is in geophysical 

well logging. 

" Only one of the several borehole geophysical 

techniques, namely vertical seismic profiling 

(VSP), has been developed to any extent. The 

petroleum industry has funded relatively rapid 

development of VSP over the past several years. 

VSP 

Vertical seismic profiling (VSP) can be done 

using both P- and S-wave surface sources (usually 

mechanical vibrators) arranged circumferentially 

around a well. Direct and reflected seismic waves 

are detected by strings of down-hole geophones 

clamped to the wall of the well or by hydrophones. 

VSP has been used mainly to trace seismic 

events observed at the surface to their point of 

origin in the earth and to obtain better estimates 

for the acoustic properties of a stratigraphic 

sequence. Oristaglio (1985) presents a guide to 

the current uses of VSP. 

Borehole Electrical Techniques 

Borehole-to-borehole and borehole-to-surface 

electrical methods appear to have considerable 

potential for application to geothermal exploration. 

In a benchmark introductory paper, Daniels 

(1983) illustrated the utility of hole-to-surface 

resistivity measurements with a detailed study of 

an area of volcanic tuff near Yucca Mountain, 

Nevada. He obtained total-field resistivity data 

for a grid of points on the surface with current 

sources in three drill holes, completed a layeredearth 

reduction of the data, and interpreted the 

residual resistivity anomalies with a 3D ellipsoidal 

modeling technique. 

The borehole electrical techniques, however, 

are in general poorly developed. One reason for 

this is that there are a large number of ways that 

borehole electrical surveys can be performed and 

it has been unclear which methods are best. At 

the same time, computer algorithms to model the 

several methods have not existed so that it has 

not been possible to select among methods prior to 

committing to the expense of building a field 

system and obtaining test data. 

RXD PROGRAM AT UURI 

The objective of our program is to develop 

and demonstrate the use of borehole electrical 

techniques in geothermal exploration, reservoir 

delineation and reservoir exploitation. Our 

approach is: 

1. Develop computer techniques to model the 

possible borehole electrical survey systems; 

2. Design and construct a field data acquisition 

system based on the results of (1); 

3. Acquire field data at sites where the nature 

and extent of permeability are known; and. 

148 

4. Develop techniques to interpret field data. 

To the present time, we have made considerable 

progress on item (1) above and we are .now at such 

a point that item (2) could be started. 

Our research staff has consisted of the 

following personnel: Stanley H. Ward, Project 

Manager; Luis Rijo, Professor of Geophysics, 

Universidade Federal Do Para, Brazil (on 2-year 

post-doctoral leave at U of U and UURI); F. W. 

Yang, Peoples Republic of China (visiting 

scholar); J. X. Zhao, Peoples Republic of China 

(visiting scholar); Craig W. Beasley (doctoral 

candidate U of U, awarded MS degree); Richard C. 

West (MS candidate at UU). Additional technical 

support has been provided by Philip E, Wannamaker, 

Howard P. Ross and Phillip M. Wright of UURI and 

by Gerald W. Hohmann of U of U. Project costs for 

Rijo, Yang and Zhao have been minimal because 

these scientists have been supported by their 

governments. TJius, a great deal has been accomplished 

at minimal cost while supporting the 

education of several students. The remainder of 

this paper will discuss the significance of our 

research to date. 

COMPUTER MODELING OF BOREHOLE ELECTRICAL METHODS 

Computer techniques for modeling borehole 

electrical geophysics have largely been lacking, 

especially for three-dimensional (3D) cases. Figure 

1 indicates conventional usage of the terms 

ID, 2D and 3D in geophysical interpretation. In 

the ID case, also called the "layered earth" case, 

the physical property of interest (resistivity for 

this study), varies only in the vertical direction. 

In the 20 case, physical property variations 

in the vertical and one horizontal dimension 

are allowed, and the anomalous body illustrated 

has the same shape in and out of the paper for infinite 

distance. In the 3D case, physical property 

variations are specified in all three space dimensions. 

Obviously, the real earth is only occasionally 

ID in nature in geothermal areas. The 

usual case is for physical properties to vary in 

all three dimensions in the earth, the 3D case. 

However, the mathematical formulations for electrical 

anomalies of bodies increase greatly in 

complexity from the ID case to the 3D case. This 

accounts for the fact that in order to begin our 

task of applying borehole electrical techniques to 

delineation of permeability, we were required to 

develop original mathematical formulations of the 

problem. 

ID 2D 3D 

p, 

h 

PX 

f= e.iiiiMit 

\\\\\ vx 

h 

vSWYvV.-"^--- 'sSSV^S 

FIGURE 1 

Illustration of the meaning of the terms ID, 2D 

and 3D in geophysical modeling. 

Pi

Thick-Body Studies ^ 

Prior to 1982, only three published papers 

considered computer modeling of downhole electrodes 

for three-dimensional bodies. Daniels 

(1977) studied six buried electrode configurations 

and plotted normalized apparent resistivity or 

apparent polarizability against such configuration 

parameters as 1) source and receiver depth, 2) 

depth/bipole length, 3) receiver distance from 

body, 4) depth of body, and 5) distance of source 

and receiver from body center. Snyder and Merkel 

(1973), computed the IP and apparent resistivity 

responses resulting from a buried current pole in 

the presence of a buried sphere. Their plots are 

center-line profiles for normalized apparent resistivity 

and normalized IP response. Dobecki 

(1980) computed the effects of spheroidal bodies 

as measured in nearby single boreholes using the 

pole-pole electrode array. These three studies 

are obviously very limited in terms of the problems 

of defining permeability in geothermal 

systems. 

In 1982, Newkirk (1982) from our group published 

a study of downhole electrical resistivity 

with 3D bodies. Using a numerical modeling technique 

described by Hohmann (1975), theoretical 

anomalies due to a three-dimensional body composed 

of simple prisms were computed. The results were 

presented in terms of 1) the potential, 2) the apparent 

resistivity calculated from the total horizontal 

electric field and 3) the apparent resistivity 

calculated from the potential. Two electrode 

configurations were considered for each 

model. Each configuration consisted of a pair of 

electrodes, where one of the electrodes was remote 

and the second electrode was located either in the 

body, for mise-a-la-masse or applied potential, or 

outside the body, simulating a near miss. Newkirk's 

computer program was used by Mackelprang 

(1985) of our group to compute a catalog of models 

due to bodies that might be of interest in detection 

of thick fracture zones. 

Figures 2a and 2b show the conventions used 

by Newkirk (1982) and Mackelprang (1985) in calculations 

of the effects of 3D bodies. The bodies 

are buried in a homogeneous earth and two of many 

options for a downhole point electrode are illustrated. 

Figure 3a and 3b illustrate anomalies on 

a surface resistivity survey produced by a narrow 

conductive body buried at a depth of 7 units with 

the electrode in the body (Fig. 3a) and off the 

end of the body (Fig. 3b). The peanut shaped 

anomaly shown in Figure 3a is particularly characteristic 

on surface resistivity surveys with the 

borehole electrode in the body. 

One basic shortcoming of Newkirk's (1982) 

algorithm is that it does not apply when the anomalous 

body becomes thin, i.e. to the case of delineation 

of fractures or thin fracture zones. To 

address this important problem, the thin-body 

studies described in the next section have been 

undertaken. 

Thin-Body Studies 

These studies are aimed at targets simulating 

fracture zones which are thin relative to their 

149 

-X 

(b) (o) • 

FIGURE 2a 

Plan view of standard model, 

/ Kl 

(Oj 

(o) 

FIGURE 2b 

Cross-section view of standard model. 

FIGURE 3a 

Surface resistivity anomaly due to deep fracture 

with downhole electrode in body. 

other two dimensions. For the most part, we have 

standardized the aspect ratios of the target dimensions 

at 10:10:1. While the effect of varying 

the contrast in resistivity has been examined.

I CD 

1.6 

FIGURE 3b 

Surface resistivity anomaly due to deep fracture 

with downhole electrode at side of body. 

most of the results are for the case of a fracture 

zone ten times more conductive than the host 

rocks. 

Four numerical techniques have been utilized 

in the studies; three have been applied with the 

D.C. resistivity method. The techniques applied 

to the resistivity problem are (1) a 3D surface 

integral equation (Yang and Ward, 1985a,b), (2) a 

30 volume integral equation (Beasley and Ward, 

1986), and (3) a 2D finite element method (Zhao et 

al., 1985). A solution for the time domain EM 

method has also been obtained which uses a 3D 

volume integral equation formulation (West and 

Ward, 1985). Elaboration on these four approaches 

is given below. 

Yang and Ward (1985a,b) present theoretical 

results relating to the detection of thin oblate 

spheroids and ellipsoids of arbitrary attitude. 

The effects of the surface of the earth are neglected 

and the body is assumed to be enclosed 

within an infinite homogeneous mass. The surface 

of the body is divided into a series of subsurfaces, 

and a numerical solution of the Fredholm 

integral equation is applied. Once a solution for 

the surface charge distribution is determined, the 

potential can be specified anywhere by means of 

Coulomb's law. The theoretical raodel results 

indicate that cross-borehole resistivity measurements 

are a more effective technique than singleborehole 

measurements for delineating resistivity 

anomalies in the vicinity of a borehole. 

Figure 4a shows cross-borehole resistivity 

responses of a vertical conductive fracture zone 

between two boreholes. The electrode configuration 

is the pole-pole array with electrode B fixed 

and electrode M moving in the second borehole. 

Several curves are plotted depending on the distance 

between the fracture and the second borehole. 

The larger anomalies occur when the second 

150 

£l.cifed. Coniigvoiion 

r:..d So.'c. 

Mo.Ing CUti'Od. 

SBt.lO SBfSBi.O 

tM»'0 

Bod, y.t. 

.'61.) 

cOJI.I 

Angl*^ 

O.O- 

B-«0r-o- 

>..,„;.,,, c 

A , 0.10 

FIGURE 4a 

Downhole cross-borehole resistivity anomalies for 

vertical fracture showing effect of varying 

distance from fracture to second borehole. 

El.cirodi Co,,.d. 

Sa»'!5 SB"SBZiO 

e«Y.o 

OOSS BOtSHOlt 

Bod, y.t. 

0' 7 

- b- J 

fO.J 

I 

o 1 

0 

- 

- 

- 

_ 

- 

- 

- 

».al.. 

O.O- 

r-o- 

'./'• 

' ' 'IV 

! i\ 

1 \ r^ eMX'7,5 

^, Coniro.t 

•0,10 

FIGURE 4b 


dipping fracture showing effect of varying 

' distance from fracture to second borehole. 

borehole is nearer to the fracture zone.. Figure 

4b shows anomalies for the same situation as Figure 

4a except that now the fracture dips toward 

the first borehole. Figure 4c shows the effect of 

varying the resistivity contrast between a dipping 

fracture and the host medium. As expected, the 

large contrast cases produce the largest anomalies. 

Figure 4d shows the change in anomaly shape 

for the dipping fracture when four electrodes are 

placed downhole instead of two (compare with Fig. 

4b, EMX = 2.5). By study of a large suite of such 

graphs as these, the comparative capabilities of 

the various' possible cross-borehole arrays can be 

determined. 

The volume integral equation approach of 

Beasley and Ward (1985) incorporates a half-space 

formulation, i.e. the earth's surface is not neglected. 

As with the surface integral equation 

technique of Yang and Ward (1985a,b), the volume 

integral equation method requires that only 

inhomogeneities be discretized. Any number of 

inhomogeneities of differing sizes and physical 

properties can be accounted for by this algorithm. 

Inhomogeneities are discretized into 

rectangular cells whose size may vary in each of 

I' 

I' 

t, 

•X- *

J-. - 

(l.ti.od. Co' 

FIGURE 4c 


dipping fracture showing the effect of varying 

resistivity contrast between fracture and host 

medium. 

COOiS, BOSEHOK 

1' '1 

Et,ei'od* Conliguroxon 

Mo.ing Bloot. Sov-c. 

Mo.,ng 6,DoU K.C.,.., 

SAT.SBr ,0 

Swr •ENYio 

Bod, s:i. 

0 • 2 

b> 2 

< .0.2 

7 

- 

- 

- 

. 

- 

.0 

Aogl.. 

o .O- 

1- •©• 

c< 

,' ' 

' K 

'^ 

1 / / 

'/ 

fl t? > 

J:>~'-" 

n.i;nr.:t, Co.iroi' 

•^••oio 

FIGURE 4d 


dipping fracture showing the effect of dipole 

length for downhole electrodes. 

the three directions. The fact that targets must 

be comprised of rectangular or cubic cells means 

that dipping bodies must be simulated by cells 

arranged in a staircase fashion. Section and plan 

views of computed apparent resistivities are the 

end product of this algorithm. The algorithm is 

flexible in that it permits a buried electrode to 

be placed either inside (mise-a-la-masse) or outside 

(near-miss) the body. The dip of the body 

and the location of the energizing electrode within 

it were both varied. The maximum depth at 

which a body could be located and still produce a 

detectable anomaly on surface surveys was found to 

be dependent, as expected, upon the position of 

the buried electrode and upon the contrast in resistivity 

between the body and the host. It was 

found that locating the buried electrode just outside 

the body did not significantly alter the results 

from those when the electrode is embedded in 

the inhomogeneity. 

Figures 5a, 5b and 5c show representative results 

from Beasley and Ward (1986). Each figure 

is a vertical section through the earth with contours 

of the resistivity anomaly. A borehole can 

be placed anywhere on this figure and the resistivity 

curve that would be observed in such a 

151 

Noi to $e""oU ^ i "=1 . •%s 

r • ^ ^ 

/-V >^ 

V 

y 

K 

*>. • . 

fc*iS£-*-i.A-"ASSe: 

HORtzcMÂL eoov 

APPARENT neSISTIVlTV-FflOM V 

SECriOH VCW f^ •3000 • m 

0"^.^5 0^«TS ^,* lofJ • m 

I SCALE:1 UMT • 

FIGURE 5c 

Subsurface resistivity contours for a horizontal 

permeable zone with an imbedded downhole current 

source. 

0 = Cuoltl 

DE = luniu 

W = .?5unil 

Scole 1 Unit 

P,'\000 

A=100 

FIGURE 6a 

Subsurface resistivity contours for a vertical 

permeable zone with current source to the side. 

Our most versatile algorithm for the borehole 

resistivity method is the 2-D finite element algorithm 

used by Zhao et al. (1985). The versatility 

of this algorithm arises from the fact that the 

entire subsurface is discretized. Since triangular 

elements are used for discretization, dipping 

bodies are readily handled. The algorithm also 

accomodates a layered-earth host environment. 

This algorithm was used to evaluate signal-tonoise 

ratio for various types of noise. 

Figures 6a and 6b show typical results from 

152 

Stole 1 Unn 1— 

p^ = 1 ooon-m 

p, =ion.- 

• = Sou'ce 

iifoce 

0 =6 ur.',ti 

DE = 0 unill 

T, = 1 uni, 

Tj = 3onit» 

W =.25 unit 

FIGURE 6b 

Subsurface resistivity contours for a vertical 

permeable zone beneath geologic structure with 

varying positions of the downhole current electrode. 

Zhao et al. (1985). Figure 6a shows subsurface 

resistivity contours in section for a vertical 

fracture with a current source outside the body. 

This plot is similar to those given by Beasley and 

Ward (1986) in Figures 5a, 5b and 5c. Figure 6b 

illustrates how subsurface topography due to geologic 

structure affects results. Note that the 

anomaly due to the fracture is obscured to a great 

extent by the resistivity pattern created by the 

contact. This is due in part also to the relatively 

large distance of the fracture from the 

downhole current source, shown by the star. A 

current source in a borehole closer to the fracture 

would cause a much clearer anomaly. 

All computations by Yang and Ward (1985a,b) 

and Zhao et al. (1985) were performed on an HP9826 

desk top computer with 1.6 Mbytes of memory. The 

algorithm used by Zhao et al . (1985) is currently 

being extended to 3-D. It is probable that the 

HP9826 wil.1 accomodate the 3-D version. If so, 

these modeling programs could easily be used in 

the field with no need to return to a large 

computing facility. 

From the above studies we tentatively conclude 

the following: the cross-borehole method 

produces larger anomalies than does a single-borehole 

method; the cross-borehole anomalies using a 

pole-pole array are smaller than those for a 

cross-borehole dipole-dipole array; the crossborehole 

mise-a-la-masse method produces larger 

anomalies than for the other cross-borehole 

OE 

II 

TJ

' X • , 

methods; and, the anomalies uue to a thin sheet 

were generally t.ierally much smaller smaller than those for a 

sphere. as is to be expected. 

, Using a 3-0 integral equation algorithm 

developed by San Filipo and Hohmann (1985), West 

and Ward (1985) performed a model study to evaluate 

the time-domain electromagnetic (TDEM) response 

of a horizontal conductive body (fracture 

zone) imbedded in a half-space. Simplifying 

assumptions in the algorithm allow modeling only 

of bodies with two vertical symmetry planes with 

sources directly above or below. The source 

transmitter is a large square loop located on the 

surface of the earth. Receivers are located in 

boreholes at various locations in the vicinity of 

the body. Responses are computed at 60 time steps 

at intervals of 0.4 ms for a total data window of 

24 ms. EM field decay curves and plots of decay 

versus depth are obtained for all three components 

of the primary, secondary, and total responses. 

The results are expressed in terms of percent 

difference plots, and are still under study at 

this time. 

Surface-to-borehole EM in which a large 

transmitter is coaxial with the well and a downhole 

detector is run in the well may provide useful 

information on the location of conductive 

fractures intersecting the wellbore. Whether this 

technique will work in cased wells and whether a 

"crack" anomaly can be distinguished from a 

stratigraphic conductor are topics under study. 

The above discussion outlines our research to 

date. Other current research involves a model 

study using the VLF (very low-frequency) method as 

well as developing a borehole inversion scheme 

using the finite-element technique. Inversion of 

the 3D integral equation is also being investigated. 

An inversion scheme which can incorporate 

multi-array data is an ultimate goal. Interpretation 

of complex borehole field data from geothermal 

sites may then become a reality. 

DISCUSSION 

The problem of selecting an appropriate 

borehole electrical system is quite complex. 

Variables include where to place the electrodes, 

i.e. how many on the surface and how many down 

each borehole, and whether to use direct-current 

galvanic resistivity, which each of the above 

figures illustrate, or some alternating current, 

electromagnetic scheme. It is clear that the 

computer based study of these questions is cost 

effective in helping select and design an optimum 

field system. 

Our current opinion is that the more data one 

can collect the better one should be able to characterize 

the subsurface. We have therefore been 

making a preliminary investigaton of the design of 

a system for obtaining both borehole-to-borehole 

and borehole-to-surface data simultaneously. Such 

a scheme is conceptually illustrated in Figure 7. 

We believe we are nearing the stage when a field 

system can be designed with the very real hope of 

yielding much more subsurface information than can 

be realized by presently available systems. 

153 

••^.(Ji^'i i-AiuVAV-'boiii-tiuLu iiL-:î:i I i Vl'l'V SuKVLV 

A, M, K, B.-oo 

- 4 - 3 - 2 - 1 0 1 J 3 4 

A.. 

M., 

V 

• LONG LATERAL ARRAY-AgB. MjNj •CONVENTIONAL LOGGING TRUCK 

• SURFACE-TO-BOREHOIE—AsB. MjNj •POTENTIAL AND CURRENT 

ELECTRODES ON SURFACE AND 

• BOREHOLETO-SUHFACE-ABB. MJNJ DOWNHOLE 

• MISEA-LA-MASSE- 

*°iini*""" •"ARID SEQUENCING THROUGH 

MBNBOIMSNS EIECTRODES 

FIGURE 7 

Conceptual illustration of a multi-array borehole 

resistivity system. 

REFERENCES 

Beasley, C. W., and Ward, S. H., 1986, Threedimensional 

mise-a-la-masse modeling applied 

to mapping fracture zones: Geophysics, 51, 

January. 

Brace, W. F., 1958, The mechanical effects of pore 

pressure on the fracturing of rocks: Geol. 

Survey Canada, Paper 68-52. 

Daniels, J. J., 1977, Three-dimensional resistivity 

and induced-polarization modeling 

using buried electrodes: Geophysics, 42, 

1006-1019. 

Daniels, J. J., 1983, Hole-to-surface resistivity 

measurements: Geophysics, 48, 897-97. 

Dobecki, T. L., 1980, Borehole resistivity curves 

near spheroidal masses: Geophysics, 45, 

1513-1521. 

Glenn, W. E., and Hulen, J. B., 1979, A study of 

well logs from Roosevelt Hot Springs KGRA, 

Utah: 2n_ SPWLA 20th Ann. Logging Sympos. 

Trans., II. 

Glenn, W. E., and Ross, H. P., 1982, A study of 

well logs from Cove Fort-Sulphurdale KGRA, 

Utah: Univ. Res. Inst., Earth Sci. Lab., 

rep. 75. 

Grindly, G. W., and Browne, P. R. L., 1976, Structural 

and hydrological factors controlling 

the permeabilities of some hot-water geothermal 

fields: \n_ Proc. Second United Nations 

Sympos. on the Development and Use of Geoth. 

Res., San Francisco, 1, 377-386.

.• Halfman, S. E., Lippmann, M. J., Zelwer, R., and 

Howard, J, H., 1984, Geologic interpretation 

of geothermal fluid movement in Cerro Prieto 

Field, Baja, California, Mexico: Bull. Am. 

Assn. Petr. Geo!., 68, 18-30. 

Hohmann, G. W., 1975, Three-dimensional inducedpolarization 

and electromagnetic modeling: 

Geophysics, 40, 309-324. 

Keys, W. S., and Sullivan, J, K., 1979, Role of 

borehole geophysics in defining the physical 

characteristics of the Raft River geothermal 

reservoir, Idaho: Geophysics, 44, 1115-1141. 

Mackelprang, C. E., 1985, A catalogue of total I 

horizontal electric field resistivity models i 

using three-dimensional conductive bodies and 

a downhole current electrode: Earth Sci. • | 

Lab., Univ, Utah Research Inst. Rept., in 

press. 

) 

Moore, J. N., Adams, M. C, and Stauder, J. J., '_ 

1985, Geologic and geochemical investigations 

of the Meager Creek geothermal system, 

British Columbia, Canada: Proc. Tenth ; 

Workshop on Geoth. Res. Eng., Stanford Univ., ^ 

Stanford, CA. 

Newkirk, D. J., 1982, Downhole electrode resis- '. 

tivity interpretation with three-dimensional [ 

models: Masters Thesis, Dept. of Geology and 

Geophys., Univ. of Utah. 

1 

Oristalgio, M. L., 1985, A guide to the current | 

uses of vertical seismic profiles: 

Geophysics, 50, in press. 

I 

San Filipo, W. A., and Hohmann, G. W., 1985, 

Integral equation solution for the transient I 

electromagnetic response of a three-dimen- i 

sional body in a conductive half-space: '< 

Geophysics, 50, 798-809. 

Sanyal, S. K., Wells, L. E., and Bickham, R. E., i 

1980, Geotherraal well log interpretation 

state of the art - Final report: Los Alamos 

Scientific Lab. Rep. LA-8211-MS. 

West, R. C, and Ward, S. H., 1985, The borehole 

transient EM response of a three-dimensional 

fracture zone in a conductive half-space: to 

be submitted to Geophysics. 

Yang, F. W., and Ward, S. H., 1985a, Single- and 

cross-borehole resistivity anomalies of thin 

ellipsoids and spheroids: Geophysics, 50, 

637-655. 

Yang, F. W., and Ward, S. H., 1985b, On sensitivity 

of surface-to-borehole resistivity, 

measurements to the attitude and the depth to 

the center of a 3-0 oblate spheroid: 

Geophysics, 50, 1173-1178. 

Zhao, J. X., Rijo, L., and Ward, S. H., 1985, 

Evaluation of the ratio of signal-to-noise in 

cross-borehole electrical surveys: submitted 

to Geophysics. 

154

Geolhermal Resources Council TRANSACTIONa VOL 9 • PART I. Augusl 1985 

A E I O U: ACCELERATED EXPLORATION for INTEGRATED and OPTIMAL UTILIZATION 

A Strategy for Geothermal Resource Development at Department of Defense Installations 

Dennis T. Trexler Thomas Flynn George Ghusn, Jr. and Caria Gerrard"" 

Division of Earth Sciences UNLV 255 Bell St. Reno, Nevada 

"•"Energy Program Management Office Naval Weapons Center, China Lal

Trexler et al. 

PRELIMINARY SURVEY 

Energy needs 

and suitability 

for occurrence of 

Geotherraal Resources 

PRELIMINARY 

ENVIRONMENTAL 

ASSESSMENT 

STOP 

YES 

NO 

FIGURE 1, 

PRELIMINARY 

FEASIBILITY STUDY 

Strategy for Geothermal Development 

at Department of Defense Installations 

The integrated program approach that is currently 

underway at the Marine Corps Air-Ground Combat 

Center (MCAGCC), Twentynine Palms, California, 

deraonstrates the benefits of resource development 

by the directed efforts of agencies familiar with 

military operations and geothennal energy. 

PRELIMINARY SURVEY 

Interest in developraent of geothermal resources 

beneath the MCAGCC was stimulated by the 

report of a well, 122 ra deep, with a water temperature 

of 73°C, located 3.6 km southeast of the Cencer's 

boundary. tm^cyaf/fUj^ 6o**- 7 

Warra ground water in the Twentynine Palras area 

tias been known for at least 30 years. Wells drilled 

for domestic water north of the city of Twentyline 

Palras have reported temperatures of 40-73°C. 

Wiggins (1980) reported 3 wells ranging in tempera- 

:ure from 48°C to 63°C. The approxiraate boundary 

)f the geothermal area in the vicinity of Twentyline 

Palras was described in Leivas and others 

[1981) as extending approximately 15 km in an eastjest 

direction and 6 km north-south. 

The Center encompasses approximately 2,600 

square kiloraeters of the southern Mojave Desert. 

°he administrative and housing area is located 8 km 

74 

YES 

DEFINE RESOURCE 

Drilling 

Teraperature 

Measurement s 

Pump Tests 

EXPLORATION 

Utilize: Geology 

Geochemistry 

Geophysics 

YES 

PROCEED WITH 

DEVELOPMENT 

STOP ) 

north of the city of Twentynine Palras, California 

(fig. 2). Large buildings such as offices, barracks 

and classrooms are heated by a central boiler 

plant employing a low pressure steara and distribution 

system. Individual and multiple family 

housing employ individual gas-fired forced air 

heating systems. 

An expeditionary air field (EAF) is located at 

Camp Wilson, approxiraately 10 km northwest of the 

Center's administrative area. The only permanent 

structures at Camp Wilson are 14 shower and lavatory 

buildings. Water is heated by fuel oil. 

The annual expenditures for heating oil and 

natural gas for the entire Center were $2,050,000 

for fiscal 1983 (Facilities Engineer personnel per. 

coram., 1983). 

EXPLORATION 

Geophysical exploration was performed by the 

Geotherraal Utilization Division, Naval Weapons Center, 

China Lake. Gravity and raagnetic surveys indicated 

a geologic structure, the Bullion Mountain 

fault, trenditig northwest-southeast beneath the 

MCAGCC administrative area and trending southeasterly 

towards the geotherraal well mentioned above. 

Other geophysical anoraalies tended to confirm Che 

i

Figure 2. Index map of MCAGCC, 

Twentynine Palms, California 

tistence of northwest trending structures subparllel 

to the Bullion Mountain fault. These are 

rom east to west: 1) Mesquite Lake fault; 2) Surrise 

Spring fault; and 3) Emerson Copper Mountain 

lult system (fig. 3). 

;S0URCE DEFINITION 

Seven sites for teraperature gradient drilling 

ire selected based on geophysical surveys and 

-oxiraity to the Center's administrative area. The 

•illing program was supported by the Navy and the 

S. Department of Energy, as a cooperative program 

reement, and supervised by the Division of Earth 

iences. University of Nevada, Las Vegas (Trexler 

d others, 1984). A pre-drilling conference was 

Id at MCAGCC to appraise base personnel of our 

tent to proceed with teraperature gradient drillg 

and to ascertain what restrictions would be 

aced on drilling operations. 

The drilling plan specified drilling to a 

pth of 304 m or bedrock, which ever came first, 

nee no wells had been drilled at the Center to a 

pth of 304 m or greater, blowout prevention 

uipment was required on the first hole. Hole No. 

(fig. 3) was located adjacent to a housing area 

d as near to the suspected trace of the Bullion 

jntain fault as possible. Quartz monzonite bedck 

waa encountered at 201 ra; drilling continued 

268 m. Maximum mud return temperature recorded 

ring drilling was 27°C. 

Hole No. 2 was located 1.37 km southwest of 

le No. I, perpendicular to the strike of the 

lllon Mountain fault. This location is near the 

75 


Mesquite Lake fault which was considered to be a 

favorable controlling structure for geotherraal 

fluid migration- 

Hole No. 2 was completed to a depth of 304 ra 

without encountering bedrock. Maximum raud return 

teraperature of only 27°C suggested that if a geothermal 

resource was present it was very deep. 

The third drill site was located approxiraately 

half-way between teraperature gradient hole No. 1 

and temperature gradient hole No. 2 (fig. 3) along 

the trend of the gravity anomaly and 2.1 km to the 

north of temperature gradient hole No. 2. This 

location would confirm if the Bullion Mountain 

fault (gravity anomaly) was the controlling structure 

for the geotherraal fluids. 

This hole was completed to 335 m and maximum 

mud return temperatures were 30°C. These data confirmed 

that the Bullion Mountain fault, in the vicinity 

of the Center's administrative area, was not 

the controlling structure for the raigration of geothermal 

fluids. 

After analyzing the results of drilling, it 

was decided by DES and Navy personnel to drill different 

structural blocks on the Center to determine 

which faults controlled the raigration of geothermal 

fluids. 

Temperature gradient hole No. 4 was located 

immediately east of the Bullion Mountains (east of 

the Bullion Mountain fault, fig. 3), to ascertain 

if the geothermal fluids reported south of the Center 

were controlled by faults on the east side of 

the Bullion Mountains. Bedrock was encountered at 

271 m and drilling was terminated at 280 m. Maximum 

mud return temperature was 29°C at 280 m which 

indicated that the geothermal fluids are not in 

this structural block. 

At this point, DES and Navy personnel agreed 

to drop two reraaining primary sites near the administrative 

area and focus on other secondary sites 

west of the Bullion Mountain fault. This was done 

in an effort to locate the controlling structures 

for the geothermal fluids. These two additional 

sites were chosen on opposite sides of the Surprise 

Spring fault. A major logistical problem surfaced 

because these sites are located on training ranges 

with restricted access. Teraperature gradient hole 

No. 5 was drilled while permission to enter the 

training area was obtained. 

Site 5, is located 3 miles west-northwest of 

the Center's administrative area. It is situated 

between the Mesquite Lake fault on the east an Surprise 

Spring fault on the west. Maxinura mud return 

temperatures were 34°C, indicating the presence of 

geothermal fluids. The hole was to be drilled to 

335 ra, however, a bit change was required at 287 m 

and, upon tripping back into the hole, circulation 

could not be recovered. Subsequent attempts to 

recover circulation failed and temperature gradient 

hole No. 5 was completed to 287 m.

Trexler et aL 

•^s^:^ Tortoise high density habitat 

Figure 3. Composite map showing important geologic, geothermal, and environmental features at MCAGCC 

Once permission to enter the training area was 

received, hole No. 6 was drilled to a depth of 335 

m. Maximum mud return teraperatures were 39.4°C, 

however, after termination of drilling and prior to 

trip-out, the mud return temperature increased 

1.4°C in 20 minutes during circulation. 

Hole No. 7 is located west of the Surprise 

Spring fault (fig. 3). The hole was completed to 

323 m and the raaximum mud return teraperature was 

76 

FAULT 

only 23''C. The low mud return teraperatures tentatively 

indicated' that geothennal fluids were 

migrating up the Surprise Spring fault and flowing 

east. 

All drill holes were cased with 6.35 cm T. (, 

C. iron pipe capped on the bottom and filled with 

water. The holes were back-filled with cuttings 

and a cement seal was placed from ground surface to 

3.3 m. 

1

SMPERATURE GRADIENTS 

Temperature gradient measurements were made on 

jbruary 13th and 14th, and February 27th and 28th, 

984, two and four weeks after the termination of 

ie drilling program. Temperature measurements 

;re made at 6 ra intervals. 

A maximum temperature of 32.6°C was raeasured 

: 268 m in hole No. 1. The temperature gradient 

ilculated over the interval from 61 m to 244 m 

JS l.3°C/100 m. Hole No. 2 had a BHT of 29.7''C 

\d a gradient of 2.7°C/100 ra. A sirailar temperaire 

gradient of 2.7°C/100 ra was raeasured in hole 

3. 3. The temperature gradient in hole No. 4 was 

.6''C/100 ra which is quite similar to holes 2 and 

The teraperature gradients in holes 1 through 4 

robably reflect the regional background teraperaire 

gradient for this portion of the Mojave block, 

lich is 2.5 to 3.0°C/100 m. 

A maximum temperature of 5l.6°C was measured 

C 287 m in hole No. 5 (fig. 4). The teraperature 

radient calculated in the interval between 110 ra 

id 287 ra was 8"'C/100 ra. As shown in figure 4, the 

radient remains positive at the bottora of the 

jle. Hole No. 6 had the highest measured teraperaire 

of all holes drilled during this phase of geolermal 

development at MCAGCC. A raaximum temperaire 

of 67.1°C was raeasured at 335 m. The temperaire 

gradient below 275 m (fig. 4) is 3.3''C/100 raid 

probably reflects the convective gradient in / | 

le geothermal reservoir. v ' 

Hole No. 7, Located west of the Surprise 

jring fault, has a maximum teraperature of 33.9°C 

: 323 m and a gradient of 3.8°C/100 ra. 

IVIRONMEOTAL FACTORS 

The ultiraate developraent of geothermal rejurces 

at the MCAGCC will require an acceptable 

ithod of fluid disposal and will have an irapact 

)on the desert ecosystem. ' Although the absolute 

ignitude of the environmental impact is not pre- 

:ntly known, selected fluid disposal options can 

: discussed in terras of the impact they will have 

1 the major environmental issues on the base. A 

jchnical report corapleted in April, 1984, desribed 

the fluid disposal options available at the 

:nter (Flynn and others, 1984). 

Four fluid disposal options, identified as 

ichnically feasible at MCAGCC, included surface 

.sposal on existing playas, fluid injection, irriition, 

and sewage disposal. Figure 5 shows a sug- 

:sted utilization rationale that includes all four 

id that may be easily accommodated by the existing 

ise structure. 

Nine major environmental issues were also 

lentified and the ramifications of each, with 

ispect to geotheirmal fluid utilization, were disissed. 

The nine issues and pertinent comments are 

resented in Table 1. 

77 

^ 

0-1 

50- 

100- 

150- 

E 

£ 

•,• 

Q, 

O 

o 

200- 

250- 

300- 

350- 

10 

"T 

20 

Hole 5 

T—r 

30 40 

Temperature 

50 60 

C 

Figure 4. Temperature gradient 

profiles of holes 5 and 6 


T 

70 

Hole 6 

No environmental issues were identified that 

would preclude development of geothermal resources 

at MCAGCC. The total impact is estimated to be 

equivalent to the impact of the existing potable 

water well field and associated pipelines. 

In addition to the obvious fuel savings, several 

ancillary benefits will accrue frora the development: 

1) reduce stress on potable water aquifer 

2) enhance vegetation and tree growth with 

irrigation 

3) increase bacterial digestion efficiency 

(sewage) 

4) mitigation of dust from Deadraan Lake Playa 

80


Environmental Issue 

1. Land use 

2. Fish, wildlife, 

vegetation, endangered 

species 

of plants and 

animals 

i. Water quality 

. Air quality 

GINEERING FEASIBILITY 

Site Characteristics 

Well field and fluid distribution 

system will be in 

training area - present potable 

water distribution system 

Is located along roads in 

training area. Proposed surface 

disposal on playa (Deadman 

Lake) represents area of 

minor concern. 

There are no species of fish 

within the study area. Alchough 

some sensitive species 

have been identified surrounding 

che base, the prospects 

of geothermal utilization 

and surface disposal (on 

playas) represents no more 

hazard than present activities 

associated with training. 

The habitats of two sensitive 

species, indigenous to the 

area, have been identified 

and will not be seriously 

affected by proposed development. 

There are no permanent surface 

waters within the study 

area that can be used as a 

source of potable water. 

Geothermal waters are likely 

CO contain slightly high concentrations 

of fluoride and 

boron. 

Although geochermal fluids 

for direct-use rarely contain 

appreciable amounts of noncondensable 

gases, a chemical 

analysis is warranted. 

Estiraated teraperatures of the geothermal 

uids at a depth of 610 m near hole No. 5 range 

ora 80''-85°C based on the observed teraperature 

adient. The priraary uses for fluids at these 

mperatures are space heating and domestic hot 

ter. These uses employ existing technology and 

inmercially available equipraent. 

Cost effectiveness is a priraary concern at the 

liter. The costs for a new geothermal heating 

stem include a production well, piping system, 

sposal system, and end-user heating retrofits. 

:h of these costs increase as the service area 

Table 1. 

78 

Environmental Issue 

5. Hot springs 

6. Physical geology 

a) subsidence 

b) induced 

seismicity 

7. Noise 

8. Socioeconomics 

9. Archaeological/ 

cultural 

resources 

Site Characteristics 

There are no therraal springs 

presently flowing within the 

study area. 

The geothermal reservoir rock 

at MCAGCC, Twentynine Palms, 

is nearly identical to the 

unconsolidated formations 

that produce non-thermal 

drinking waters. Although 35 

feet of drawdown has occurred, 

there have been no reports of 

subsidence within the well 

field. 

This is generally associated 

with deep, high-pressure injection 

and is not likely to 

be a problem. 

The area is presently used 

as an air-ground combat 

training center. Also, no 

residential, recreational or 

breeding areas are adjacent 

to proposed production area. 

Will likely reduce the cost 

of heating at Mainside, Secondary 

application may also 

reduce amount of fluids 

pumped from non-thermal 

aquifers. An economic feasibility 

study is presently 

being conducted. 

Archaeological surveys have 

been successfully used to 

locate and isolate sensitive 

cultural areas (I.e., Surprise 

Spring) within the 

study areas. Proposed development 

will not affect sites. 

expands. Critical to the geothennal system is the 

location of the production well in close proximity 

to the heat load. 

Relative to the known geothermal reservoir, 

Ocotillo Heights, which is coraposed of 250 family 

housing units, is the closest existing large heat 

load. A prelirainary cost estimate for converting 

Ocotillo Heights (O.H. on fig. 3) to geotherraal 

heating from a source at hole No. 5 is presented 

in Table 2. 

The estimated offset natural gas consumption 

is 150,000 therms per year or S90,000/year in natural 

gas costs. This gives a simple payback period 

I 

[ 

E 

Ol 

ai 

b; 

Wc 

h.

EOTHEFttVlAL RESERVOIR— FLUID TEMPERATURE 75°C 

± 

Reinjection Well(s) 

tricf Space Heating 


Surface Disposal- 

evaporation pond on playa 

Irrigation 

Aquaculture 

Silviculture 

Direct Utilization of Geothermai Energy 

MCAGCC Twentynine Palms, CA. 

Table 2. 

.,000 ft. production well & pump $ 150,000 

0,000 ft. 8" insulated pipe $25/ft.* 500,000 

,000 ft. 6" insulated pipe $30/ft. 60,000 

50 retrofits @ $l,200/unit 300,000 

0,000 ft. disposal line @ $4/ft.** 40,000 

Estimated Total $1,050,000 

•Installed on surface 

**Buried 

2 years. If the geotherraal well can be located 

cent to Ocotillo Heights, the conversion cost 

500,000 less and the corresponding simple paytime 

is 6 years. 

If the new construction is located in the 

nity of hole No. 5, then these new buildings 

i be ideal candidates for geothermal space 

ing. Supply line costs will be minimized and 

rofit" costs would be limited to the cost difitial 

between heat exchangers and conventional 

ices. 

79 

CONCLUSIONS AND RECOMMENDATIONS 

Trexler et at. 

This report demonstrates the utility of integrating 

data from those well defined parameters 

that most influence the success of geothermal resource 

utilization. The teraperature, depth and 

approxiraate areal extent of a low-temperature geothermal 

resource (70°C) was deterrained on the basis 

of data derived from geological, geophysical, and 

teraperature gradient hole drilling surveys carried 

out by the Geothermal Division at China Lake Weapons 

Center and the Division of Earth Sciences, 

UNLV. Oata from those studies were used to develop 

use-scenarios that included heat and water utilization 

in a framework that was consistent with existing 

military operations and environmentally beneficial 

. 

Data are presently being collected that will 

help determine the engineering and econoraic feasibility 

of offsetting all or part of the Center's 

energy demand with geothennal heat. A report by 

Bakewell and Renner (1982) included an economic 

analysis of using geotherraal fluids for MCAGCC 

which was based on assuraptions which have been 

found to be totally raisleading. The important data 

are listed in Table 3: 

Resource 

Character 

Location 

Temperature 

Depth 

Table 3. 

Bakewell & 

Renner 1982 

unknown 

63°C 

90 m 

Trexler and Others 

1984 

between #5/6 on raap 

70°C - 85°C 

350-600 ra 

The conclusion that the attractiveness of geothennal 

utilization is sensitive to co-locating the 

resource and end use is correct. The report differs, 

however, in assuming the location of the 

resource, in ignoring optional uses for the fluids, 

and for not considering separating isolated heat 

loads from the entire base heat load. 

The principal recommendation of this report is 

to define the eastern-raost limit of accessible and 

usable geothermal fluids by drilling temperaCurei 

gradient holes. A series of 2-3, 600 m holes i 

the area of Ocotillo Heights and west will provid 

the required data. Following this, a pump test o 

a properly sited well will coraplete the resoorc 

definition phase of the program. 

Detailed engineering and economic feasibility 

studies using the most accurate resource data would 

then be warranted. Preliminary estimates show that 

econoraic benefits may be realized within 6 years if 

the Ocotillo Heights residential area is retrofitted 

for space and water heating. More significantly, 

new construction located at the site of the 

geothermal reservoir would achieve a payback in a 

shorter time period if geothermal heating systems 

were included during construction.



Many people participated in the successful 

completion of this project and the authors would 

like to acknowledge their contributions. John 

Crawford and Bill Holman, of the San Francisco 

Operations Office of the U.S. Department of Energy, 

provided pertinent suggestions during site selection 

review and the drilling phase of the program. 

Geothermal Utilization Division, Naval Weapons Center, 

China Lake, personnel were instrumental in 

conceiving the project, providing geophysical data 

used in drill site selection, and assisting in temperature 

gradient measurements and site restoration. 

Individuals of the G.eothermal Utilization 

Division who provided this support are Al Katzenstein. 

Jack Neffew and Ted Mort. Carl Halsey's 

critical review of the drilling report showed that 

the characterization of specific mission contraints 

must, utilize and be functionally interwoven with 

the preliminary qualification limit. 

Logistical support during activities at the 

Marine Corps Center was provided by Lt. Col. C.E. 

Schaffer and the staff of the Installations Division, 

specifically Staff Sgt. William Flunimerfelt, 

who provided assistance in acquiring necessary permits 

for drilling activities at the MCAGCC, and 

baseline data for the fluid disposal study. Stu 

Hammonds helped secure data for the engineering 

feasibility study, and Charles Miles and David 

Holmes of the Naval Civil Engineering Laboratory 

were instrumental in funding this prograra. 

We would also like to acknowledge the drilling 

contractor, Fred Anderson and Son Exploration 

Drilling, Inc., for a job well done and for their 

patience while drill site locations and depths were 

changed because of data acquired during drilling. 

Without the assistance and support provided by 

these individuals and organizations, this project 

would not have been completed. 

This work was funded under the following contracts: 

DOE Contract No. DE-AC03-83SF11956; Navy 

Work Order No. N60530-M-23BQ; DOE Grant No. 

DE-FG03-85SF15555. 

Finally, many thanks to U.R. Bearmatt for 

keeping the lines of communications at MCAGCC open. 

10-4. 

REFERENCES 

Andersen, S.O., 1975, Environraental impacts of geotherraal 

resource development on comraercial 

agriculture: A case study of land use conflict: 

in proceedings. Second United Nations 

Symposium on Development and Use of Geothermal 

Resources, San Francisco, CA, pp. 1317-1321. 

Bakewell, C.A., and Renner, J.L., 1982, Potential 

for substitution of geotherraal energy at 

domestic defense installations and White Sands 

Missile Range: U.S. DOE Contract No. ACOS- 

80NV10072, NTIS No. DE82007081. 

80 

Flynn, Thomas, Ghusn, G.E., Jr., and Trexler, D.T., 

1984, Geothermal fluid disposal options Marine 

Corps Air-Ground Combat Center, Twentynine 

Palras, California: Report prepared for Naval 

Weapons Center, China Lake. CA, pp. 47. 

Higgins, C.T., 1980, Geothermal resources of California: 

California Div. of Mines and Geol., 

Geologic Data Map Series No, 4, scale 

1:750,000. 

Leivas, E. , Martin, R.C, Higgins, C.T., and 

Bezore, S.P., 1981, Reconnaissance geothermal 

resource assessment of 40 sites in California, 

report of the third year, 1980-81 of the U.S. 

Department of Energy; California State-Coupled 

Program for reservoir assessment and confirmation, 

243 p. 

Trexler, D.T., Flynn, T. , and Ghusn, G.E. , Jr., 

1984, Drilling and thermal gradient measurements 

at U.S. Marine Corps Air-Ground Combat 

Center, Twentynine Palras, California: Final 

Report, U.S. DOE Contract No. AC03-83SFI1956, 

OTIS No. DE84012803. 

Trexler, D.T., Koenig, B.A. , Flynn, T. , Bruce, 

J.L., and Ghusn, G., Jr., 1981, Low- to moderate-temperature 

geothermal assessment for 

Nevada: Area specific studies:' U.S. Dept. of 

Energy contract no. AC08-79NV10039, NTIS No. 

DE81030487.

Geolhermal Resources Council TRANSACTIONS, VOL 9 - PART I. Augus11985 

GEOCHEMICAL EXPUJRATION OF THE CALISTOGA GEOTHEBMAL RESOURCE AREA, 

NAPA VRLLEy CALIEDRNIA 

Kent S. Murray^-'-'-'' Mark L. Jonas^^' Carlos A. Lopez (3) 

(1) Depart^ment of (Seology, Caiifomia State University 

6000 J St. Sacramento, Caiifomia 95819 

(2) Mackay School of Mines, Departnent of Geology, 

University of Nevada, Reno, Nevada 89557 

(3) Caiifomia Energy Ooinmission, 1516 9th St., Sacramento, 

California 95814 

ABSTRACT 

Chemical analysis of well waters in the upper 

Napa Valley, near the city of Calistoga, 

California suggest that the upwelling and 

localization of fluids with temperatures up to 

135°C, may be related to faulting or fracturing 

along the geographic axis of the Napa Valley. 

Calculated temperatures from chemical 

geothermometry are always higher than measured 

temperatures, with maximum values often 50°C 

higher than sampling temperatures at well point. 

Two shallow, subsurface systems of moderately-high 

temperatures were detected using waters with 

locally high chloride values (Cl ISOppm). • Maximum 

reservoir temperatures may exceed ISCC Mixing 

of the geothermal water with shallow, cool 

groundwaters is indicated by intermediate 

concentrations of Cl, F, and B, by ternary 

molality plots of Cl, B and HCO-,, and by a 

trilinear diagram of major cations and anions. 

INmBUCTION 

The Calistoga geothermal area, located near 

the head of the Napa Valley, in northern 

California is a shallow hydrothermal convection 

system of low-to-moderate temperature (Fig. 1). 

The hottest wells—The Geysers at 135"C, and wells 

near Pacheteau's spa at 120°C—are coincident with 

the geographic axis of the valley (Fig. 2). 

Tertiary volcanic rocks, resting unconformably 

on rocks of the Jura-Cretaceous Franciscan 

assemblage form the most prominent surficial 

exposures in the highlands around Calistoga and 

along the margins of the valley. The volcanic 

rocks which consist predominantly of ash flows, 

welded and partially welded tuffs, and tuff 

breccia, agglomerate and rhyolite are considered 

to be part of the Sonoma Volcanic Field of Upper 

Plicene age (Sarna-Wojcicki, 1976; Fox, 1983). 

The youngest published date on this volcanic 

sequence, obtained from the summit of Wt. St. 

Helena seven miles north of Calistoga, is 2.9+,2ray 

(Mankinen, 1972, p. 2065). Further to the 

northeast, lies the Clear Lake Volcanic field 

which has been active into the Holocene (Fox, 

1983). Two large negative gravity anomalies 

centered both north and south of Calistoga maybe 

339 

related to the geologically young volcanism. 

Although the cause of the anomalies is uncertain. 

Youngs and others (1980) suggested that underlying 

the southem anomaly could possibly be an elongate 

intrusive mass. Although little additional 

information is available concerning the northern 

gravity anomaly, the area is immediately southwest 

of the Clear Lake volcanic field. Thus, both the 

northem and southem anomalies may well r^resent 

shallow magma chambers that were the source of the 

late Pliocene-Pleistocene volcanic sequences in 

the Calistoga-Clear Lake region. It is thus 

possible that residual heat from either of these 

chambers is the driving mechanism responsible for 

the geothermal activity at Calistoga. 

Rocks underlying the Napa Valley have 

undergone gentle folding and faulting. Major pre- 

Pliocene northwest trending fault zones in 

Franciscan rocks have laeen mapped to the northwest 

of the Napa Valley by Fox and others (1973), but 

the Sonoma Volcanic sequence and Quaternary 

alluvium mask any pre-Sonoma faulting that may be 

present within the upper Napa Valley. Minor 

faulting of the Sonoma Volcanic sequence however, 

was noted just to the north of Calistoga, as well 

as some relatively large-scale faults of probable 

normal displacement approximately five to six 

kilometers southwest of Calistoga (Fox and others, 

1973; Fox, 1983). 

Fox and others (1973) have also indicated the 

presence of a major northwest-trending thrust 

fault along which Franciscan rocks have been 

thrust over rocks of the Sonoma Volcanic field at 

an angle of 20° to 30°. This fault is a major 

feature of the western limb of the Napa Valley 

syncline. Its eastern terminus has been 

interpreted as possibly being coincident with the 

current axial plane of the Napa Valley (Youngs and 

others, 1980). The eastern terminus of this 

thrust may represent the major structural 

discontinuity underlying the upper Napa Valley as 

suggested by Waring (1915), Faye (1975), and 

ISylor (1981), enabling geothermal fluids to rise 

into the alluvial and fractured volcanic aquifers 

beneath Calistoga. 

Geofiiysical studies (Youngs and others, 1980) 

undertaken by the California Division of Mines and

.Vlurray, et al. 

38-30' 

Figure 1. Hap showing the general location of the Calistoga Geothermal Resource area 

(Modified from Fox and others, 1973). 

Figure 2. Isochloride lines outlining the Calistoga geothermal anomaly. The hottest wells in the 

area—135°C and 120°C—occur at The (teysers (TG) and Pacheteous Spa (P), The zones 

afpear to line along an inferred fracture zone which coincides with the geogr^hic axis 

of the valley. 

340 

122'30f 

• ^ • ' 

J3S.. 

m

Geology ((aJMG) within the Napa Valley-Calistoga 

area indicated several areas of possible, but 

inconclusive evidence of faulting associated with 

areas of known geothermal waters (Taylor, 1981). 

In particular, seismic refraction and •' 

electrical resistivity surveys (Youngs and ot±ers, 

1980) have detected possible zones of hot water 

that maybe associated with this faulting near Ihe 

Geysers. The resistivity sections indicate an 

irregular but somewhat elongate distribution of 

the conductive zones. Some of the lines, running 

perpendicular to the axis of the valley, do not 

show any lower depth limits for the resource near 

the center of the valley, perhaps suggesting the 

upwelling of fluids. In this model, the hottest 

water wells would be expected along the fracture 

zone, or geographic axis of the valley, while 

progressively cooler water, caused by mixing with 

surface water, would be encountered in wells 

located closer to the margins of the valley, away 

from the fracture zone. Our field and geochemical 

work has shown that geothermal waters do indeed f\ 

rise near the geographic axis of the valley, and j 

further, that these waters have a distinctively! 

different chemistry than water from the margins of 

the valley. As a result, water chemistry can bel 

used to isolate and trace the geothermal system H 

throughout the tfapa Valley - Calistoga area. " 

Sanple 

Nmitier 

H-002-80 

1-+1-004-80 

2-«-015-81 

3-M-O10-81 

4-+1-018-81 

5-G-016-80 

6-G-001-80 

7-C-O09-81 

8-0-012-80 

9-G-O16-80 

lO-G-020-80 

H-G-025-80 

12-O-037-80 

13-G-044-80 

14-G-058-80 

15-G-096-80 

16-G-097-80 

17-G-105-80 

18-G-I11-80 

G-112-80 

X9-G-115-80 

20-G-116-80 

21-G-122-80 

22-O-143-80 

23-O-181-80 

24-G-201-80 

2S-G-205-80 

26-O-006-80 

27-G-O77-80 

28-G-083-80 

29-G-089-80 

30-0-121-80 

3X-G-135-80 

32-&-150-80 

G-165-80 

33-G-169-80 

34-G-173-80 

3S-G-175-80 

G-195-80 

36-G-196-80 

37-G-205-80 

Depth 

meters feet 

54.9 

61.0 

97.6 

189.0 

64.0 

3.7 

91 

58 

60 

123 

59 

61 

125 

61 

61 

72 

46 

76 

63 

- 

61 

57 

38 

73 

46 

64 

55 

91 

73 

54 

42 

79 

134 

65 

49 

107 

146 

57 

73 

61 

55 

180 

200 

320 

620 

210 

12 

300 

190 

198 

400 

193 

200 

410 

200 

200 

235 

152 

250 

207 

- 

200 

187 

125 

240 

151 

210 

180 

300 

240 

210 

139 

260 

440 

212 

160 

350 

480 

186 

240 

200 

180 

Sanpling 

temp. "C 

26 

33 

38 

51 

36 

12 

91 

135 

81 

37 

116 

61 

52 

40 

74 

85 

95 

44 

104 

30 

35 

41 

15 

27 

20 

64 

55 

16 

19 

19 

22 

15 

19 

20 

20 

40 

22 

21 

22 

19 

55 

pa 

7.05 

7.10 

7.16 

7.90 

8.36 

7.75 

7.00 

8.50 

7.20 

6.50 

7.75 

6.97 

6.70 

6.65 

6.65 

8.05 

8.40 

7.40 

7.85 

6.40 

7.00 

6.95 

6.98 

6.88 

5.99 

6.33 

6.35 

6.25 

6.80 

5.98 

6.18 

6.90 

6.52 

6.42 

6.00 

6.10 

6.32 

6.20 

5.64 

6.18 

8.00 

(a 

176 

174 

183 

204 

170 

13 

198 

206 

202 

184 

190 

179 

188 

180 

191 

192 

222 

200 

205 

239 

143 

238 

29 

138 

121 

173 

186 

13 

12 

10 

11 

26 

61 

107 

17 

54 

55 

40 

12 

41 

21 

R 

16 

8 

5 

6 

4 

L 

8 

9 

7 

4 

7 

10 

7 

12 

4 

6 

10 

7 

9 

7 

10 

7 

4 

5 

4 

11 

7 

2.5 

2.5 

2.5 

2.5 

4 

9 

11 

7 

2.5 

2.5 

12 

4 

10 

9 

13 

16 

7 

8 

14 

22 

5 

2 

2 

28 

30 

22 

8 

11 

10 

10 

4 

6 

6 

10 

6 

8 

17 

14 

19 

13 

16 

9 

51 

30 

13 

15 

14 

15 

16 

20 

16 

21 

12 

26 

15 

GEOCHEMISTRY 

Murray, et al. 

We have analysed a variety of geochemical 

parameters to form a preliminary assessment of the 

low-to-moderate temperature resource at Calistoga. 

Water chemistry for selected water wells within 

the Calistoga area shown in Table 1. Chemical 

geothermometry results for several of these wells 

are presented in Table 2. The equations used to 

calculate the geothermoraeters are shown in 

Appendix A. Two shallow, localized, subsurface 

systems of elevated temperatures are indicated by 

geothermometry, using water with high chloride 

values (Cl 180ppm). A subsurface aquifer of 

intermediate depth generally yields maximum values 

approximately 50°C higher than the sampling 

temperatures registered at shallow depths. A 

deeper aquifer is indicated by Na-K-Ca 

geothermometry to have a temperature range of 100° 

to 135°C Several of the calculated temperatures 

however, are much higher, perhaps suggesting the 

potential of still greater temperatures at depth. 

Recent deep drilling in the greater Calistoga area 

by the CDMG and the Caiifomia Eiiergy Commission 

however, indicate only moderate increases in/ 

temperature with depth, are expected unless the/ 

wells are located directly along the fracture zone j 

shown in Figure 2. For example, in two test wells 

drilled by the CDMG to depths of 787 and~836 feet, 

Ma 

6 

6 

2 

1 

4 

4 

1 

0.5 

0.5 

2 

1 

4 

1 

4 

1 

0.5 

0.5 

0.5 

0.5 

2 

3 

3 

7 

8 

18 

5 

2 

3 

21 

7 

3 

5 

7 

9 

9 

3 

20 

11 

5 

• 8 

9 

ppra 

Si


EMfiU a uvllm 

•UMt Um^. 

W-OOl-tO 

t-î-CM-W 

i-n-oii-ti 

3-H-01D-4) 

*-«-01l-«) 

^^>.41t-M 

*

^C Bomw of (tw VaAmf 

Figure 4. Trilinear diagram showing three 

distinct water types in the greater 

Calistoga area. 

northeast and southwest border of the valley. The 

proportions of cations and anions in the 

groundwater from a variety of wells in the upper 

Napa Valley, exhibit three distinct water types 

when plotted on a trilinear diagram (Piper, 1953). 

Water from the southwestern border areas of the . 

valley can be easily distinguished from mid-valleyj 

water by a more variable, but generally lower! 

chloride compositions, and increased HOO^, SO^ and\ 

Fe concentrations. Water from the northeastern 

border areas, as typified by wells 5, 27, and 28 

are even lower in Cl with higher concentrations of 

Ca and Mg. Well 7, plotting within the midvalley, 

high-Cl range, most likely representis the 

true chemical characteristics of the deeper/ 

geothermal reservoir. This water is high in Cl 

(201ppm), B {9.8ppm) and F (ll.Sppm) and low in Fe 

(Oppm), SO^ (Oppm) and Mg ( O.Sppm). It has a 

calculated Na-K-Ca temperature of 159°C. The 

scatter associated with the remainder of the 

analyses plotting within the NaCl-type range 

probeibly reflect minor mixing with surface waters. 

CONCLUSIONS 

The source of the geothermal component of 

waters in the upper Napa Valley may be related to 

one of two possible shallow plutonic bodies 

located both north and south of the city of 

Calistoga. Geophysical and geochemical evidence 

suggests the presence of a subsurface fracture 

zone aj^roximately coincident vith the geographic 

cixis of the valley. The fracture zone ajârs to 

act as a conduit for the upward migration of 

fluids. The hotter wells in the Calistoga area 

are distributed along the geographic axis of the 

valley, have similar Cl/B ratios and are high in 

Cl, B, F and Na. These wells also indicate higher 

temperatures by geothermometry, inplying a deeper 

aquifer source. 

.Murray, et al. 

As the geothermal water seqps upward along the 

fracture zone it migrates laterally towards the 

margins of the valley, Emd gradually becomes 

enriched in Fe, SO^ and HCOj by mixing with the 

cool, near surface groundwater. A comparison of 

these geochemical indicators on trilinear 

diagrams suggests various degrees of mixing 

between the geothermal waters and shallow fresh 

groundwater, at different locations throughout the 

greater Calistoga area, and can thus be used to 

trace and map the geothermal waters. 


The authors are grateful to Les Youngs and 

Roger Chapman whose constructive suggestions and 

discussions of geophysical analyses greatly 

contributed to ideas and supportive data presented 

in this paper. We are also indebted to Catherine 

Light and Faustino Flores for their invaluable 

technical assistance in compiling the final 

manuscript. This research has in part supported 

by a grant from the Caiifomia Energy Commission. 

REFERENCES OTED 

Arnorsson, S., 1983, Chemical equilibria in 

Icelandic Geothermal Systems - Implications 

for Chemical Geothermometry Investigations. 

Geothermics, V.12, No. 2/3, p. 119-128. 

Back, W., 1961, Techniques for Mapping of 

Hydrochemical Facies. U.S. Geological Survey 

Professional Paper 424-D, p. 380-382. 

Barnes, I., 1970, Metamorphic Waters from the 

Pacific Tectonic Belt of the West Coast of 

the United States: Science, V. 168, p. 973- 

975. 

Benjamin, T., Charles, R., and Vidale, R, 1983, 

Thermodynamic Parameters and Experimental 

Data for the Na-K-Ca Geothermometer: Journal 

of Volcanology and Geothermal. Res. 15, p. 

167-186. 

Ellis, A.J., 1970, Quantitative Interpretation of 

Chemical Characteristics of Hydrochemical 

Systems: Geothermics Special Issue 2, p. 

516-528. 

Faye, 1975, Groundwater Quality and its Relation 

to Geologic Structure and Formations in the 

Napa Valley area, California: Unpublished 

thesis. 

Fournier, R.O., 1977, Prediction of Aquifer 

Temperatures, Salinities, and Underground 

Boiling and Mixing Processes in Geothermal 

System: In Proceedings of the 2nd 

International Symposium on Water-rock 

Interaction, 1977, Strasbourg, Prance. 

Fournier, R.O., 1979, A Revised Equation for the 

Na/lc Geothermometer: Geothermal Resources 

Council Transactions, Vol. 3 p. 221-222.


Fournier, R.O., and Potter, P.W., II, 1979, 

Magnesium Correction to Na-K-Ca Chemical 

Geothermometer: Geochlmica et Cosmochimica 

Acta, V. 43, p. 1453-1550. 

Fournier, R.O. and Truesdell, A.H., 1973, An 

Empirical Ite-K-Ca Geothermometer for Natural 

Waters: Geochlmica et Cosmochimica Act:a, V. 

37, p. 1255-1275. 

Fournier, R.O., White, D.E., an Truesdell, A.A., 

1976 Convective Heat Flow in Yellowstone 

^btional Park: United âtions Symposium on 

Development and Use of Geothermal Resources. 

San Francisco, 1975, V. 1, p. 731-739. 

Fox, K.F., Jr., Sims, J.D., Barrow, J.A., and 

Helley, E.J., 1973, Preliminary Geologic Map 

of Eastern Sonoma County and Western Napa 

County, California: U.S. Geological Survey 

Miscellaneous Field Studies Map MF-483 (also 

Basic Data Contributions 56), Scale 1:62,500. 

Fox, K.F., Jr., 1983, Tectonic Setting of Late 

Miocene, Pliocene, and Pleistocene Rocks in 

Part of the Coast Ranges North of San 

Francisco, California: U.S. Geologic Survey 

Professional Paper 1239, 31 pp. 

Hull, CD., and Elders, WJV., 1984, Geochemical 

Exploration Techniques Applied to Well Waters 

of the South San Bernardino Geothermal Area 

and the Upper Santa Ana River Valley, 

California: Geothermal Resources Council 

Bulletin, V. 13, No. 10, p. 4-8. 

Mankinen, E.A., 1972, Paleomagnetisra and 

Potassium-Argon Ages of the Sonoma. Volcanics. 

California: Geological Society df America 

Bulletin, V. 83, No. 7, p. 2063-2072. 

Piper, A.M., 1953, A Graphic Procedure in the 

Geochemical Interpretation of Water Analyses. 

U.S. Geological Survey, Water Res. Div. 

Groundwater Notes, (Seochemistry. No. 12, 14 

PP- 

Sarna-Wojcicki, A.M. 1976, Correlation of Late 

Cenozoic Tuffs in the Central Coeist Ranges of 

California by Means of Trace and Minor 

Element Chemistry. U.S. Geological Survey 

Professional Paper 972, 29 pp. 

Taylor, G.C, 1981, Calistoga Geothermal Resource 

Area: Caiifomia Geology; Caiifomia Division 

of Mines and Geology, p. 208-217. 

Waring, G.A., 1915, Springs of California: U.S. 

Geological Survey Wat:er-Supply Paper 338, 410 

P- 

APFEIOU A 

Rcyiat.innft £0^ { 

IMP 

(1) Criatobolitc! fC - 4.78-lc}q Si02 

(2) aialc:edony 

(3) 

(«) Quartz 

• (5) 

(6) le - K 

(7) 

(8) la - K - Ca 

(5) 

(10) 

1112 

f^: - 4.91-109 siOj 

UH 

t°C = 5.31-log Si02 

fC ' S.lS-log SiOj 

_1522_ 

t'C •• 5.75-lcjg SiO^ " •"•'•'^ 

12^2 571 1^ 

fx: - i.483+iog((e/K)" '".15 

_SU_ 

t°C =• 0.993tlog(l&/K>" 

1H7 

f^ = 2.2«+lC)g(te/K)«filog( .Ca/le) " 273.15 

4-340'\: 

B =• 4/3 for .Ca/Ki 1 s t"C 100 

B - 1/3 for .Ca/te 1 I f^: 100 

z222iiat°C 

=• log(Mj/1!)-6.31og( .Ca/IB)-64.2 " 273.15 

t < lOO'C 

(1) 

2S-180»C (2) 

(cxmcJucrtive)' 

100-180'^: (2) 

(adiabatic) 

0-250'C (1) 

(QDnductive) 

1116 -„ ,. 

fC • lc3g(Ki/K)-lO.0551c)g( *a/>^)*-l.«9 " •'"•IS 

t > 100»C 

(11) fk} correction dt-^'X: = 10.66-4.741Rt325.87(logR)2 

for ffi-^-Cd ^ 5 5 7 2 5 

-1.032x10^ (logH) '/r-l. 968ia0 ' (logR) ^/r' 

(12) NJ - U 

+1.605x10'(logR)'/r2 

R - {(«g/(K«Ca-Hlg)) X 100 

1000 

t"C = log(iaAi)*0.38 " 273.15 

T = K" 

cone, in ppn for eq. (1) tbru (7); Molar for oq. (8,9,10,12)1 

equivalents for (11). 

10O-250"C (1) 

100-30CI"C (3) 

25-250'C (1) 

sourc:eo: (1) Foumier (1977); (2) Amoroon (1983) i (3) Foumier (1979); 

W Ftoumler ( Tmesdell (1973); (5) Benjainln s others (1983) i 

(6) Foumier $, Potter (1979); (7) FoulUac k Wchard (19SI). 

Youngs, L.G., Bacon, C.F., Chapman, R.C., Higgins, 

C.T., Majmundar, H.H., and Taylor, G.C, 

1980, Resource Assessment of Low-and 

Moderate-Temperature Geothermal Waters in 

Calistoga, Napa County, California: Report 

of the Second Year, 1979-1980 of the U.S. 

Department of Energy - California State 

Coupled Program. .1 

344 

W 

(5) 

(5) 

(6) 

(7)

Geolhermal Resources Council. TRANSACTIONS. Vol. 10. Seplember 1986 

A GEOCHEMICAL MODEL OF THE CALISTOGA GEOTHERMAL RESOURCE 

NAPA VALLEY, CALIFORNIA 

ABSTRACT 

The Calistoga Geothermal Field consists 

of a shallow, moderate 

temperature resource located at the 

head of the Napa Valley in northern 

California. Li)ce many near-surface 

low-to-moderate temperature (180ppm, B>8ppm, F>7ppm and 

Na>170ppm. By noting the locations of 

water wells displaying the highest 

concentrations of these elements, the 

position of the deep water source, the 

Kent S. Murray (1,2) Mark L. Jonas (3) 

(1) Departnent of Geology, California State University 

6000 J St. Sacramentc-, Calilornia 9S819 

(2) California Energy Coimission, 1516 9th St. 

Sacrane.-itc;, California 956K 

(3) Canp Dresser and McKee, 71G S. Broadway Suite 201 

Walnut Creek, California 9

flurray and Jonas 

Figure 1. Map showing the general location of the 

Calistoga Geotherraal Field in the upper Napa Valley, 

California. Cross-valley profile lines show location of 

wells used in the composite diagram shown in Figure 3. 

Figure 2. Map of the greater Calistoga area showing the 

linear nature of the B, Cl, and Hg anomalies. The light and 

dark shaded areas circumscribe a cluster of wells with water 

temperatures in excess of 50°C, and 100°C respectively. 

140 

•l! 

I I 

-.m 

1

Geophysical studies by Youngs and 

others (1980) at Calistoga, and an 

initial assessment of the geothermal 

resource at Calistoga by Taylor and 

others (1981) also indicated several 

areas of possible faulting associated 

with the areas of known geothermal 

resources, but were uniable to confirm 

the actual existence of a fault or 

fracture zone. Finally, recent 

physical evidence developed during a 

test drilling program has also tended 

to support this hypothesis, but without 

confirmation (Murray, 1986). 

The mapping of geochemical anomalies 

(areas of anomalously high concentra- /> 

tions of Cl, B, F, Na, and Hg) however, 

has been successfully employed 

elsewhere in California to not only 

locate faults but to trace waters 

transported upward along these shear 

zones (Barnes, 1970; Hull and Elders, '' 

1984). The application of these same 

techniques to the Calistoga Field has 

resulted in a good correlation between 

geophysical data and the occurrence of 

the hot water resource. High chloride 

concentrations, in particular, have 

been used to locate the source of the 

deep hot water zones, with the highest 

chloride values representing the location 

of probable upwelling of thermal 

fluids from depth (Hull and Elders, 

1984). In addition, Chloride, along 

with B, F and Hg can also be used to 

delineate the actual boundary of the 

geothermal resource. 

Figure 2 is a composite diagram 

combining areas of anomalously high Cl, 

B, and Hg along with an outline of 

wells discharging water in excess of 

50°C. The notably linear appearence of 

this diagram tends to confirm that the 

upwelling of geothermal fluids is 

localized along a vertically permeable 

fault or fracture zone trending 

parallel the axis of the upper Napa 

Valley. The upwelling geothermal 

fluids can also be recognized by a 

localized increase in the potentiometric 

surface, coincident with wells 

displaying the highest values of B and 

Cl. The location of the two areas with 

the highest surface discharge 

temperatures, the California Geyser at 

135°C and Pacheteau's at 1210C are also 

aligned along the projected trace of 

the fault or fracture zone (Fig. 2) . 

Both of these areas produce hot water 

from wells drilled to depths of 192 and 

201 feet respectively. 

141 

A CONCEPTUAL MODEL 

Murray and Jonas 

A conceptual model of the Calistoga 

resource based upon water chemistry and 

soil mercury profiling is shown in 

figure 3. The model is similar to 

other shallow hydrothermal convection 

systems found throughout the Basin and 

Range and Cascade Range provinces of 

California, Nevada and Oregon. Hot 

water flows up the vertical fault and 

spreads laterally into a relatively 

thin aquifer under pressure. The roc)c 

matrix above the aquifer is assumed to 

be sufficiently permeable to allow 

vertical mixing with the overlying 

fresh water aquifer (Murray, 1986). 

The fluid then flows through the 

aquifer losing heat by conduction to 

the caprock and basement. 

A corollary of this model is the 

development of a distinctive temperature 

reversal below the aquifer. 

Figure 4 is a schematic diagram which 

illustrates the evolution of this 

temperature gradient with time. In the 

case of Calistoga, the graph can also 

be used to predict the temperature 

profile at any given location away from 

the fault. 

Figure 5a is a series of temperature 

gradient profiles from five geothermal 

wells located in the upper Napa Valley 

along profile line D-D'(Fig. 1). The 

wells were logged originally by 

Occidental Geothermal Inc. and the data 

published by Youngs and others (1980). 

Figure 5b is an interpretive diagram 

showing the relationship of the wells 

to the geothermal- aquifer and their 

relative distance away from the central 

fault or fracture zone. As shown in 

Figure 5a, two of the temperature 

profiles, wells 6 and 9, show a 

distinctive temperature reversal with 

depth, at 164 and 190 feet respectively. 

The profiles from other wells, 

while displaying no reversal, can be 

easily interpreted in terms of distance 

from the fault or fracture zone, or the 

depth of the well relative to the 

geothermal aquifer. For example, 

wells 7 and 8 show a continuous 

increase in temperature with depth, and 

are thus probably located within the 

permeable fracture zone. Whereas, 

wells 6 and 9 penetrated through the


ComposfTe ProfTIo of Chemical TrocerA 

Upper Nopa Vafloy-Canatooa 

8»i*r*«o Trsa 

.::L 

Mercury and CMorido Proliles UpDer Napa Valley-CalislOQa 

M«'Ourv in SO'I 

M«rci^y In soil 

I kilomeief 1 

Figure 3. Conceptual model of the 

Calistoga Geothermal Field based on the 

concentrations of Cl and Hg. The lower 

cross-sections show the measured values 

of Cl and Hg along three separate 

traverses across the upper Napa Valley 

(see Fig. 1). 

14Z 

0 

Q 

=1 

-1.0 

-2.0 

R::::::::-^^.^^ ' 

1 1 . AOU'CII'.' • * • ~ I • 1 •• >• • • • • - . 

' I /"^ 

__,„——^ 

'l 

, y 

^^ / 

-^7 

/ '1 

/ 1 

Figure 4. A schematic diagram 

illustrating the evolution of faultcharged 

hydrothermal systems with time. 

Modified from Benson and others (1981). 

(a) 

mixing. 

Cb) 

sem i-pcrmab'9 

îmoernioabio boundary 

Figure 5. (a) Five temperature 

gradient logs selected from a series of 

geothermal wells drilled by Occidental 

Geotherraal Inc. (b) Diagrammatic crosssection 

across the Napa Valley 

illustrating the relationship between 

the temperature gradient profiles shown 

in (a) and the geothermal aquifer. 

oo 

.1 

•î

feothermal aquifer into a zone of 

iooler temperature. Well number 10, on 

he other hand, shows no change in 

.emperature gradient with depth and 

lischarges water of a much cooler 

emperature than the other wells 

lentioned. This suggests that well 10 

s probably not of sufficient depth to 

ntersect the main body of the 

eothermal aquifer (Youngs and others, 

980) . 

lESERVOIR VOLUME ANALYSIS 

The Calistoga geothermal reservoir 

s a complex, heterogeneous system of 

ock and water. The temperature 

:ontour of 50°C, indicated on Figure 2, 

ircumscribes a cluster of water wells 

ithin the greater Calistoga area that 

ischarge water in excess of 50°C below 

depth of 200 feet. The boundary line 

as drawn to enclose the v/ells, then 

odified slightly to fit geophysical 

nd geochemical evidence as 

ppropriate. The boundary as drawn, 

erves as an estimate of the lateral 

xtent of the geothermal aquifer, an 

rea of approximately 5.79 scjuare 

iles. 

Youngs and others (1980) vertically 

ivided the upper Napa Valley into four 

jbsurface zones. From top to bottom 

lese are: (1) alluvial sediments 

rom the surface to 120 feet in depth, 

>) alluvial sediments below 120 feet 

id extending to the top of the 

iderlying southwest dipping pyroclas- 

.c beds (a cumulative thickness 

iproaching perhaps 14 00 feet on the 

luthwest side of the valley). 

) impermeable pyroclastic material 

imposed wholly of volcanic ash and 

h-flow tuff; and, (4) saturated 

roclastic material and interbedded 

diments underlying zone 3. 

Zone 2 appears to represent the main 

idy of the Calistoga reservoir. The 

erage thickness of the aejuifer was 

timated by Youngs and others (1980) 

' be approximately 64 0 feet. This 

ickness represents a volume of rock 

d water above 25°C and is considered 

conservative estimate based on the 

ility of the aquifer to transfer heat 

conduction, with time, to the 

rrounding rock matrix. The actual 

servoir thickness, as shown in 

gure 3, is probably relatively thin, 

rhaps no more than 100 feet, based on 

(nperature gradient profiles and 

bsurface water chemistry. 

143 

Murray aniJ Jonas 

A reservoir volume can thus be 

calculated from the boundary 

determinations and an estimated 

average thickness. From these 

calculations, a conservative, steady 

state aquifer yield of approximately 

13,500 to 20,500 acre feet or 4.4 x 10^ 

to 6.6 X 109 gallons has been estimated. 

Current withdrawal of water from 

the resource by bottlers of mineral 

water and spa operators is estimated at 

55 X 10^ gallons per year. Assuming no 

recharge to the system .and no further 

development, the reservoir would thus 

be expected to last approximately 100 

years. 

Geocheraical mapping, however, has 

demonstrated that recharge of the 

resource is taking place along a ij 

central fault or fracture system, [[ 

suggesting that further developraent of 

the resource is feasible. The rate of 

natural charge and the rate of 

downstream discharge (surplus water) 

currently leaving the the system, 

however, is not Icnown and cannot be 

accurately determined. Thus an accurate 

prediction of reservoir longevity 

is not possible at this time. The 

determination of reservoir depletion, 

however, can be made through careful 

well monitoring, and/or numerical 

modelling techniques. Detectable 

drawdown of the potentiometric surface 

and seasonally corrected declines of 

chemical tracers such as chloride, in 

selected wells, will serve as a measure 

of the rate of reservoir depletion. 

CONCLUSION 

Geocheraical mapping of the Calistoga 

Geothermal Resource Area has led to the 

development of a conceptual model which 

satisfactorily explains the chemical 

and thermal characteristics of the 

reservoir. Anomalously high values of 

Cl, B, F, Na and Hg were used to locate 

a central fault or fracture system of 

high vertical permeability through 

which water flows to the surface. 

A volumetric analysis was completed 

based on geochemistry, geophysics and 

the distribution of thermal wells 

displaying temperatures in excess of 

50°C. Recharge versus withdrawal rates 

suggest that the resource could undergo 

reasonable development without 

detriment; however, accurate depletion 

rates must be based on subsequent well 

monitoring and/or numerical modelling 

studies.



The authors gratefully acknowledge 

the efforts of Richard Thomas, whose 

careful review significantly iraproved 

the manuscript. We are also indebted to 

Faustino Flores and Rexford Smith for 

their invaluable assistance in 

compiling the final manuscript. This 

research was in part supported by a 

grant from the California Energy 

Commission to the City of Calistoga. 

REFERENCES CITED 

Barnes, I., 1970, Metamorphic waters 

from the Pacific Tectonic Belt of 

the west coast of the United 

States: Science, V. 168, p. 973- 

975 

Benson, S.M., Bodvarsson, G.S., and 

Mangold, D.C, 1981, Reservoir 

engineering of shallow faultcharged 

hydrothermal systems: 

Proceedings Seventh Workshop 

Geothermal Reservoir 

Engineering, Stanford University. 

Faye, R.E., 1973, Groundwater hydrology 

of northern Napa Valley, 

California: U.S. Geological Survey 

Water-Resources Investigations 13- 

73, 64p. 

Faye, R.E., 1975, Groundwater quality 

and its relation to geologic 

structure and formations in the 

Napa Valley area, California: 

Unpublished Thesis. 

Hull, CD., and Elders, W.A., 1984, 

Geochemical exploration techniques 

applied to well waters of the south 

San Bernardino geothermal area and 

the upper Santa Ana River valley, 

California: Geothermal Resources 

Council Bulletin, V.13, No.7, 

p.2063-2072. 

Murray, K.S., Jonas, M.L., and Lopez, 

C.A., 1985, Geochemical exploration 

of the Calistoga Geothermal 

Resource Area, Napa Valley 

California: Geothermal Resources 

Council Transactions V.9, p.339- 

344. 

Murray, K.S., 1986, Geothermal Resource 

Assessment - City of Calistoga: 

California Energy Commission Draft 

Report 8Op. 

144 

Sarna-Wojcicki, A.M., 1976, Correlation 

of late Cenozoic tuffs in the 

central Coast Ranges of California 

by means of trace and minor element 

chemistry: U.S. Geological Survey 

Professional Paper 972, 29p. 

Taylor, G.C, Bacon, C.F., Chapman, 

R.H., Chase, G.W., and Majmundar, 

H.H., 1981, Drilling addendum to 

resource assessment of low-and 

moderate temperature geothermal 

waters in Calistoga, Napa Valley, 

California: Report of the Second 

Year, 1979-80 of the U.S. Dept. of 

Energy-California State Coupled 

Program 73p. 

Waring, G.A., 1915, Springs of 

California: U.S. Geological Survey 

Water Supply Paper 338, 410p. 

Youngs, L.G., Bacon, C.F., Chapman, 

R.C, Higgins, C.T., Majmundar, 

H.H., and Taylor, G.C, 1980, 

Resource Assessment of low-tomoderate 

temperature waters in 

Calistoga, Napa County, California: 

Report of the second year, 1979- 

1980 of the U.S. Department of 

Energy-California State Coupled 

Program. 104p. 

f

INTRODUCTION 

Geothermal Resources Council. TRANSACTIONS. Vbl. 10. Seplember 1986 

ANALYSIS AND INTERPRETATION OF THERMAL OATA FROM THE BORAX LAKE GEOTHERMAL PROSPECT. OREGON 

David D. Blackwell (1) Shari A. Kelley (1) and Robert C. Edmiston (2) 

(1) Departraent of Geological Sciences, Southern Methodist University, Dallas, Texas 75275 

(2) Anadarko Production Company, 835 Pine Rd., Santa Rosa, California 95101 

The results of geothermal exploration at the 

Borax Lake geothermal prospect, Harney County, 

Oregon with emphasis on Interpretation and 

thermal modeling of temperature gradient data are 

presented in this paper. The total heat loss of 

the Borax Lake system is calculated and compared 

to other Basin and Range geothermal systems. 

Thermal models are developed to test the 

hypothesis that the location of geothermal 

activity at Borax Lake is controlled by the 

structures and/or stratigraphic section 

associated with the buried horst block. In 

addition, downward continuation modeling is used 

to estimate the subsurface configuration of 

isotherms ranging from 160 to 190°C. The Borax 

Lake area of southern Oregon is located in the 

northern part of the Basin and Range province. It 

lies in the Alvord Valley, a north-trending, 

complex graben between the horst blocks of the 

rugged Steens Mountains to the west and the Trout 

Creek Mountains to the east (Figure 1). 

' 

'-, -A 

V: g 

- 13 -^ 

: 5 

: O 

C 

Z 

; -A 

\ 

> 

'- z 

: ^ 

z 

•^ ^ ~ 1 KM 

l 

t. 

z. 

— 

_~ 

E 

.,!«*• 

/'', 

'..^ 

Figure 1. Location map of Borax Lake area. The circles represent drill holes less than 76 (n deep; the 

dots represent drill holes deeper than 76 m. 

169 

t Ml 

SCALE 

'^ 

', 

'.

ilackwell, Kelley and Edmiston 

thermal systera. Both gravity (Cleary and others, 

1981, and unpublished Anadarko reports) and 

seismic reflection surveys (unpublished Anadarko 

reports) Indicate that a burled, north-northeast 

trending horst block exists beneath the geothermal 

area. The location of the fault that 

bounds the eastern margin of this horst block 

coincides with the location of the hot springs at 

Borax Lake (Figure 1). The horst block becomes 

narrower and has less relief to the north, and 

may not be present north of the south end of 

Alvord Lake. 

Geothermal activity Is found at two other 

locations In Alvord Valley. Mickey Springs are 

approximately 45 km northeast of the Borax Lake 

Hot Springs. Alvord Springs emerge frora a fault 

along the eastern front of the Steens Mountains 

at a locality about 25 kra north-northeast of the 

Borax Lake Hot Springs. The regional heat flow 

in this part of Oregon Is 60-100 mWm"' and the 

regional geotherraal gradient is ilO-60''C/km 

(Blackwell and others, 1978), based on sparse 

data. Since no Pliocene or (Juaternary volcanic 

rocks are found in the area, there is no evidence 

that a volcanic heat source is responsible for 

the geothermal activity in Alvord Valley. Thus 

the heat source for the geothermal systems 

appears to be the natural heat flow of the 

region. The minimura depth of circulation of 

ground water required to reach the highest 

observed temperature In the Borax Lake system of 

160°C (320°F) would be 3-U km, and the minimum 

depth to reach the Inferred reservoir temperature 

of igO'C (375°F) would be 1-5 km. This situation 

Is analogous to the Basin and Range province of 

northern Nevada which Is the site of several 

major geothermal systems such as Desert Peak, and 

Dixie Valley. These geothermal systems are 

described by Edmiston and Benoit (1981) and by 

Benoit and Butler (1983). 

DISCUSSION OF THERMAL DATA 

The thermal modeling presented In this report 

is based on data collected during the exploration 

process (Gardner and others, 1980; and Nosker and 

ôsker, 1981). Information from interpretations 

Prom the gravity and seismic reflection surveys 

Is incorporated into the structural features of 

the geothermal models. 

A location map of the temperature gradient 

loles in the area is shown in Figure 1 . The 

iverage geothermal gradient for the depth 

interval of 61 to 76 ra in each hole based on the 

'eports Is shown on Figure 2. There are two 

llfferent sets of temperature-depth data. The 

loles with the W designation were obtained from 

Inion Oil Company. This series of holes was 

Irilled to a nominal depth of 76 m. Another 

lerles of holes was drilled by Anadarko to a 

lomlnal depth of 150 m. The geothermal gradient 

:ontours shown in Figure 2 are based on coraputer 

lontouring of the data by GSI, Inc. An area of 

iver 20 kra* (15 mi') has gradient values of at 

east 100°C/km (5.5°F/100ft), approximately twice 

he regional average gradient, and an area of 2 

;m' (1.5 mi') has gradient values greater than 

170 

3lO°C/km {19°F/100ft) 

do not become isothermal or have negative 

gradient sections. Since the drilling and 

completion history of both of the deep holes Is 

complicated, the curves are open to different 

Interpretations. 

TEMPERATURE, DEC C 

Figure 3. Temperature-depth plot of selected 

noles. The non-equllibrura W-1 log was made !06 

lours following completion of drilling. 

As part of this study, the thermal data were 

-einterpreted. The temperature-depth data were 

reanalyzed and interpreted geothermal gradients 

jsed in subsequent modeling are shown in Figure 

1. Heat flow values corresponding to the redeter- 

li-zts' 

"jf'ioo.w-jr-";?* 

" o O 

tl. "• 

Igure 1. Map of "deep" geotherraal gradients, 

le high gradients due to shallow leakage over 

le horst were not used in preparing the map (see 

ixt). These contours were used in the downward 

intinuation modeling. 

171 

Blackwell, Kelley and Edmiston 

mined gradients were calculated, but since the 

shallow thermal conductivity does not vary, the 

heat flow and geothermal gradient contours are 

identical in shape. No terrain corrections to 

the gradients are necessary because of the very 

low relief in the valley. The gradients shown in 

Figure 1 were contoured by hand to serve as a 

second anomaly pattern for Interpretation in 

addition to that shown in Figure 2 and are 

referred to as the "deep" gradients (see 

discussion below). 

HEAT LOSS 

One of the characteristic parameters of a geothermal 

system is the rate of heat loss I.e., the 

excess heat above the background transported 

through the system by the convecting ground 

water. The flow rate of the Borax Lake hot 

springs is approximately 3500 1 min"' and the 

exit temperature is 96''C (205°F) according to 

Brooks and others (1979). The estimated reservoir 

teraperature ranges from 165''C (329''F) based on 

the quartz adlabatic geothermometer, to 176''C 

(319°F) based Qr\ the Na-Ca-K geothermometer, to 

191 °C (376''F) for the "best jri situ reservoir 

temperature" (Brooks and others, 1979). The 

actual heat loss, assuraing a temperature drop of 

81°C (the exit teraperature minus the surface 

temperature), is 2.0xl0'W. The overall heat loss 

of the system, assuming that the temperature 

field of the system is in steady state. Is calculated 

using the reservoir rainus the surface temperature. 

That value is 1.3xlO'W if the reservoir 

temperature is 190°C. The difference in the two 

values should be the heat lost to the surroundings 

during flow of the water through the system. 

The heat lost by conduction can be calculated 

by integrating a heat Mow contour map for the 

prospect. This calculation gives a value of 1.2x 

10' W above the assumed background of 80 raWm"'. 

The addition of the actual convective heat 

loss and the conductive heat loss for the prospect 

gives a total heat loss for the Borax Lake 

system of 2.7x10' W. This value compares to the 

value calculated from the assumed reservoir teraperature 

and the observed flow rate of 1.3x10' H. 

Since either method of calculating the total heat 

loss could easily have an error of ±20%, the 

agreement of the two figures is satisfactory. A 

good estimate of the heat loss of the prospect is 

3-1x10' W. 

This heat loss is equivalent to the total heat 

loss due to the regional heat flow over an area 

of 50 km'. The heat loss compares to values that 

range frora 10' to 10' W for geotherraal systeras in 

the Basin and Range province such as Grass 

Valley, Nevada, Roosevelt, Utah, Desert Peak 

Nevada and the geothermal systems in the Imperial 

Valley in California. 

FORWARD'THERMAL STRUCTURE MODELS 

As a second stage in the thermal interpretation 

the thermal structure in the valley was 

evaluated using forward modeling. In this

ilackwell, Kelley and Edriiiston 

approach the configuration of the heat source 

causing the anomaly was assumed and theoretical 

heat flow profiles caiculated' for comparison to 

the observed anomaly. The technique used was a 

two-dimensional finite difference rsolution. The 

structure of Alvord Valley has been explored by 

the seismic reflection technique -and by gravity. 

A simplified cross section based on the interpretation 

of th^. geo phys Ipal .da.ta jalong profile A-A' 

0(1 Figures 1 and lis shown ih .Figure; 5, 

Figure 5. Forward numerical models. The; cdhtact 

between- the beidropk and ^the valley fill (stippled 

area) is generalized from s^'ismic^ idata 'along 

secti'on A-A'. The generalized heat flow based on, 

the gradient data from Figur.e; 1 is shown ga the 

dashed line' on Figures 5b and 5c. 

The model shown in Figure 5a is deaigh'ed to 

investigate, the magriltuae of thermal conductivity 

refraction effect. Ttie nature of this- eTfect and 

its influence on the thermal conditions in the 

172 

Basin and Range setting are discussed- by 

Blackwell arid ' Chapmajn (1977) and Blackwell 

0983), The ther-mal GoriauGtivity ' refraction 

effect Is caused by dlffeiênces in thermal .conductivity 

between th"e low-conduct Ivity, valleyfill 

sediments -ani the higher-conductivity 

volcanic rocks. The regional heat flow used lh 

this model was assumed tb be 60 raWm"*, ..and the' 

tKermal conductivity values assumed are shown. 

The assumed suf face temperature, in all of the 

modela was IS^C. 

Based on thia baakgrouhd, conductive-heat-flow 

model, the surface heat f.low would be depresse"d, 

valley over the horst by a few percent. In 

add it ion, larger heat flow anoma lies of ± 15S 

would be present 'at the: contact between the 

volcanic bedrock of the ranges and the valley 

sedimeht's. The, temperature at a given depth in 

the' valiey would be" higher than the temperature 

at that same clepth in the volcanic bedrock 

because, of the dirference in thermal conducttVity. 

The- temperature in the horst brack would 

be, intermediate bjet.ween the- valley and the, range. 

Even tJiough the geothermal -system is due to 

transfer of heat by cbnvebtion, I'n mafiy real 

geologic .si'.tuations,, conductive modeling can tie 

used to evaluate, the. geometry of the "reservpir". 

For the conductipn raodeling to apply, the fluid 

circulation must be-' cbhfined to dlaprete paths 

rather than circulating freely through a "homogeneous, 

porous, medium," These discrete, paths canbe 

treated as ^boundaries of known- t.emperature'r, 

and tlie'ir ;geoinetry can be inferred from conductive, 

models of the surface heat flow or subsurface 

temperatures outside the circulation paths. 

The basis bf thia approa.ch ia dlaoussed by 

Blackwell and Chapman (1977) .arid by Brott and 

others (,198l). The approach is particularily 

useful in the early stages ot p'rospect evaluation 

when a- minimum of subsurface Information heeded 

for convective modeling i's not available. 

Two forward modela of jjpasjlble: isobherm configurations 

associated with a geothermal sya.tera 

[Figure's 5b and 5c) were calculated. In the model 

•shown in Figure 5b, the to"p> oT the system was 

approxi mated as a faulted horizohtal. plane of 

constant temperature (IfeCC) ;at depths of 100 ;and 

.800 m. In the model shown in Figure 5c, the heat 

'sou'rpe was approximated, by two fault zones at a 

constant temperature of 160 = C. The' location of 

the two fault zones was assumed to coincide with 

the edges o'f the horst. The assumed -temperatureia 

conservative- .because It is the temperature 

actually observed in hole W-l. the temperature; 

of the heat source (reservoir) could be higher 

{'and .the' sources correapondingly deeper) without. 

a major change In the isotherms: calculated away 

from the heat source, as long as heat transfer Is 

Gohductive throughout the region out aide the, 

paths of clfculatibh modeled as i'sothermal 

surfaces. 

The actual heat flow janomaiy is asymmetrical 

along cross section A-A', and neither of the heat 

flow curves calcurated fro'tn the finite dlffer.enc^ 

modala match this .asymmetry. When compared to 

i. 

It' 

it

the heat flow anomaly predicted from the models, 

the, actual anomaly la steeper ori the east aide 

and less steep on the weat, side. Thus if taken 

literally, the actual source would be .shallower 

or have a steeper dip oh the eaat side than 

either model configuration. Ori the west aide the,, 

actual source Would be deeper, 'or have a 

shallower dip than aaaumed Iri the model'a. 

The model with a heai—horizontal aource 

(Figure 5b) haa gradienta that ane too steep.' on 

both si diss and doea not raatoh the' width of the 

observed anomaly. Thus the source would appear 

to be broader than the model configuration. The. 

model of the aystem as tHo: discrete fault zones^ 

(Figure 5c) .has a heat flow anomaly that ahowstwo 

discrete peaks, ih contrast to the heat flow 

anomaly from the actual system. However, the 

calculated width ,'of the anomaly matchea: the 

observed anomaly width better than the single 

aource model. The calculated anomaly shape also 

matches the observed' anomaly shape' clpsely ori Jihe 

east 'aide of the profile. 

The raodel with a source within the horst 

(Figure 5b) appears to give the better fit to the 

overall ahape of the observed anoraaly. However,, 

tfie discriete heat flow peaks predicted by the 

two-jfault, model (Figure '5c) may be .obscured by 

shallow h'orizcntal flow, and/or the .gradient d'ata 

may be sparse enough that such fapi'd; latec;al 

variations are not resolved; 

DOWNWARD CONTINUATION MODELING 

Finally an Inverse modeling'technique'waa used 

to evaluate the poasible subsurface ther'tnal 

condition based on the .observed surface pattern. 

The downward continuation techriique' (Brott and 

othera, 198-1) was. used in this part of the study. 

Gradients .from the 50-150 m depth range were 

plotted arid contoured (Figure 1). irifomatiori on 

the, structural geology of the area, provided by a 

seismic reflection survey across the thermal 

anomaly, was used to ;guide the location- of the 

geothermal .gradient contours where control waa 

sparse. The resulting ob'served profile' acrpas, 

the thermal ,a_nomaly along croas section A-A' is 

shown on Figure 6. The gradient was .determined 

at equal intervals (500 m)-, by interpolation. 

:The aelectipri of dalta spacing is equivalent to 

low pass fllteririg of the bbaerved anomaly (see 

Li arid others, 1982,. -for -a different app'roach). 

The data, set Is to spars;,e to allow more complicated 

filtering techniques. The equall'y spaced 

gradient data; were then Input into the- 'downward 

continuation modeling prbgram tb determine the 

depths of the 150, 175, and igO^C isotherms. 

The very high gradienta (greater thari about 

SSCC/kjn) fourid in a.prae, of the shallow holes over 

trie horst (aee Figure 2) must be related to the 

shallow- clroîlatlon of hot water -derived from a 

deeper aource. if the -gradients of 350''C/km found 

iri some of these shallow holes were projected tb 

depth, the predicted temperatures would be' much 

higher than those- actually observed lh t'he, two 

dee'pest. hblea. One of the. maj.or assumptions 

173 

B.Vackwell, Kelley and Edmiston 

asaociated with the downward continuation 

•technique Is that no; heat spurcea .exiat between 

the surface and the "target" reservoir. The 

exlatehee of shallow leakage violates this 

aaaumptlon. The ,only drill Hole th'at can b'e 

directly uaed to characterize the e'eothe'rmal 

gradient due to the deeper source is W-1, the 600 

m deep hole. The geothermal gradient associated 

with the 'deeper aource estimated from W-i Is 

approxi'raa'tely 250''C/ktri',. which iS; well below the 

peak values of over 100"C/km aaaoclated with the 

shallow leakage. So In order .to model the 

temperatures at depth due to the deeper heat 

source, .a maximum gradient :pF- asCG/km estimated 

from "W-l was assumed to be th'e gradient over the' 

hbr.at (site of holes W-1, W-5, W-13, W-IU, AN-6'i, 

AN-Sa, 81-l"). 

aiOT P0lrl,T NUMBER 

Figure- 6:., laotherms' along croaa- section A-A' 

calculated by the technique of downward continuation, 

fhe isotherma are superimposed oh the 

structure along the aection based on the gravity 

and seismic ihterpretatLona. Trie temperature 

gradients used in the interpretation and trie fit 

of the, calculated gradrents are shown al.so. 

fhe inferred 190

Blackwell, Kelley and Edmiston 

assumption that temperatures', will continue to 

increase with depthj which ia cons!atent with the 

"data frbm W-1. However, a sudden de.creaae of 

temperature with depth, in the lower portion of 

the shallow ayatem may occur, and our model would 

no longer be valid. If convective fluid motions 

occur in the valley sediments' then the major 

aasumption on which the Interpretation is baaed 

breaks down. The final limitation is triat there 

are large par.ts of the area; that are top -sparsely 

sampled for the horizontal gradierit'a in thermai 

gradient (heat flow) to be> well enough determined 

to constrain the cb'ntiriuatipn. 

CONCLUSIONS 

In spite of the limitations of the model-ing 

several iraportant cbnciuaio'na about the B'prax 

Lake gepthermal syatem can be reached: 

1) Th'e Borax Lake 'syateiii is a major Basin-and 

Range geothermal system with a heat losa of 

3-1x1.0,' W. The heat 'source i'a the regional heat 

flow of the area. 

2) The systera la associated with a horst block 

in' the cpnter of the* valley as delineated by 

Interpretation of gra.vity and .seismic studies. 

3) Temperaturea pf leo^C (32p°F) are- measured 

in a 500 m (!206oft) hole -in triis syatem and geochemical 

thermometry suggeats temper aturea- of 

•rgo^G (395°F)'. 

1) Based on the downward continuatibn modeling 

an area in the subsurface at a depth pf approximately 

900 m (3Cfbft-) with a size of at least ,6", 

km' {2.5 ml') and, ppssibly as large as 15 km' 

(6 mi'') has temperatures In excess of leo^C 

(320 = F);; 

5. The clpse' match between the pbserved, and 

calculated anomalies along the east side of the, 

triermal prPTll.es ia s.trong evlderice' that the; 

fault bounding the east side of the hbnst la one 

.of the: major controls on trie geothermal system. 

The» geothermai ayatem Is clearly aaaociated 

with trie hbrat. The nature of the -.BSSPciatipn; 

could be: of at least two different typaa, which 

cannot as; ye't be resolve.d. The circulation could 

be controlled by permeability iri the vplcahiC; 

baaement rooks or by permeability associated with 

fracturing, and faulting, relating to the fbrraatlpn 

of the horst. The surface leakage ia aaaocfated 

with the fault that bounds the horst block on the 

east side so soma; clrculatipn is pbvipualy 

associated with faults. While the model of the. 

sounce as confined to the hqrat seems to be the 

preferred one, 'the geometry of the, thermal' 

structure within the horst cannot be determined 

on the basis of av.allable data.. The actual area 

that might be suitable, for geothermal exploitation 

cannot be determined until deeper drllJLing 

can resolve the hature of the flow control a. 

Npnetheleaa the Borax Lake geothermal aystem 

appears to b'e a maJpr resource area and td, have 

potential for exploitation; 


The authbhs thank Anadarko Production Coiiipany 

for support for thia atudy and for permission to 

publish this paper. 

174 

REFERENCES 

Benoit, W.R., and Butler, R.W., 1983. A review of 

riigh-temperature geothermal developments in 

the northern Basiri and Range provi ne'e, in 

Gepthermal Resources Council Spec. Pub., v. 

21', p. 57-80. 

Blackwell, D.D., '1983, Heat flow 

Basin arid Range, prbvince, 

in the: nor trie rn 

in Geothermal 

RssouBces Council Spec. Rub., • V.21, p. 81-9.2. 

Blackwell, D.D., and Chapman, O.S., 1977, 

Iriterprefatibh of ; geo.thermal gcadi'erit, and 

rieat flpw data for Basin and Range- geothermal 

sys.tems, Geothermal Respurces Gouricil Trans., 

V. _i_, ;p. 1,9-20. 

Blackwell, D:!,D.., Hull, D.A., Bowen, R.G,, and 

Steele, J.L., 1978, Heat flow of Oregon, 

.Oregon' Dept. Geol. and Mineral Industrjea 

Special Paper, v. _1, 12 pp,.. 

Brook, C.A.,, Mariner, R.H., Mabey, D.R., Swanson, 

-J, ^., Gaff a nti, M.,, and Muf f ler, L.J.P., 

1979, Hydrotherraal convection systema with 

rese"rvoir temp,erature,a > 90°G, In U.S. Geol. 

Surv. Circ;., V. 790, p. 18-85. 

Brott,' C.A., Blackwell, D.D., and Morgan, P., 

1981, Cohtinuatipri' of- heat flow data: a 

metriod to conatrudt I'sotherma in gebthermal 

areas;, Geophysics, v' ^, p. 1T32-1711- 

Cleary, -J-, i Lange, I.M., Quraa r, A.I., a'rid Kr oti se, 

H.R., 1981, Gravity, isotope, and geocheraical 

'Study of the Alvord Valley geothermal area, 

Oregon: Sumraary, Geol. Soc. Amer. Bull., v. 

92, p". 3V9-322. 

Edmiston, R'.G., and Benoit, W.R., 1981, 

Characterlatlca t^t Basin arid Range geotherraal 

ayatems with fluid temperatures pf 150°C to 

200°C, Geothermal Resourcea Council Trana., 

y.&_,. p. 117-124. 

Gardner, M.C., Cox,, B.L., and Klein, (i.W., 1980, 

Temperature grabierits .and heat flow in the 

Alvord Vailey, Oregon, unpublished report to 

flnadarkp.. Productipn Co., 3 vol. 

LI, T.M.G,, Swanberg, C.A., and Fe'rguabn, J. p., 

1982, A method for filtering hot spring noise 

from shalipw ,teii)peratu'r'e gradient data, 

Geothermai Resourcea .Council Trans. , v. b_, p. 

137-V10. 

Nosker, R.E., and Noaker, s'jA., 1981, Reaulta of 

thermal gradient drilling -on the Borax Lake 

arid Alvohd Ranch prospects, Oregon-October- 

December 1981 , unpubliahed report to Anadarko 

Productipn Co., ,55 pp. 

Rytuba, J.J.-, and HcKee, E. H., 1981, Penal kal ine 

ash flow tuffs and calderaa of the McDermitt 

vbl,cahic field, southeaat Gregpn and north 

central Nevada, J_^ Geophya. Rea.:, v. 8£, p. 

8616,-8628. 

Ziago'a,. J. P., and Biackwell, D.D., 1996, A model 

for the transient temperature effects of' 

hprizphtal fluid flpw in gbotri'ermal syatems, 

j. Vol. Geotherm.., Rea.. v. il, p. 371-397.

INTRODUCTION 

In our experience, all high-temperature 

goothennal prxDducticn occurs frcm fractured rocks. 

However, the mapping and defini-tion of these 

fractures have proven to be difficult. The 

Reservoir Definition Program at UURI has concentrated 

on the development and application of 

geological, geochemical and geophysical techniques 

'-/hich aid in the definition of fractures in the 

geothermal envlrom^nt. The locations of important 

faults and fractures can often be predicted 

by placirg the geothermal occurrence within a 

regia-ial structural model that relates faul-ts and 

fractures to causative stress fields. These 

provide temperature and oomposi'tional information 

on pathways which have been sealed thrcugh hydrothermal 

alteration as well as those which are 

presently acti-ve. Fluid inclusions frequently 

also can provide a convenient method for determining 

the temperature of a resource before temperatures 

within geothermal wells have a chance to reecjui 

libra te. Since surface geophysical methods 

lack the precision necessary for fracture detection 

at reservoir depths, borehole geophysical 

methods are being investigated. 

Our geological ar«d geochemical studies have 

concentrated on down-hole samples frcm active 

high-temperature geothermal systems. The following 

docvJnents briefly -the studies which have been 

ocmpleted in these systems. Following this, our 

borehole geof^Tysical modeling studies are briefly 

described. 

VALLES CALDERA 

Studies in the Valles caldera have utilized 

samples u'hich were donated by UNOCAL as well as 

samples recently acquired through Continental 

Scientific Drilling program. 

Hydrothermal brecciation along structural 

zones may be an ijiportant process in enharcing 

permeability. A model relating the pressure 

controls of boiling to the pressure required for 

hydrofracturirg has been develcped to explain the 

process of hydrothermal brecciation. Data frcm 

fluid inclusicns confirm that the boiling process 

was the causative mechanism for brecciation. 

Studies in the Valles have also coricentrated 

on intracaldera sandstones as guides to evolution 

of the caldera complex. Sands'tone marker horizons 

are currently being investigated in detail to 

modify and improve -the intracaldera geologic 

history. These studies have already revealed the 

following ne--; information. Sands'tone horizcns, 

along with enclosing ash-flow tuff sequences, have 

been tilted up to 50° from their originally 

FHACIURE DEFINITION: 

FX)ra-IRTICN, PRESERVATION, DELINE7VTICN 

Dennis L. Nielson, Joseph N. Moore, Phillip M. Wright 

University of Utah Research Institute 

horizontal confIgura'tions. TTiis may be the result 

of caldera resurgence, or it could reflect postdepositional 

slumping or gravi-ty sliding. The 

sandstcnes clearly have served as thermal aquifers, 

second only in importance to faults, 

fractures and breccia zones. They are intensely 

altered. Pumice fragments were initially very 

porous, but have sirce been clogged wi-fch hydrothermal 

illite, fluorite, quartz, calcite and 

chlorite. Chlorite is definitely the latest 

secondary phase to be deposited; it has been 

observed forming delicate microcrystalline 

rosettes encrusting euhedral fluorite crystals. 

The al-teraticn of these sandstones illustrates 

an important reservoir concept. Although 

these rocks originally had a high permeability, 

they have been effectively sealed through hydrothermal 

alteration. The continued maintenance of 

fluid pathways tn such rocks requires fracturing 

to re-open areas sealed through hydrothermal 

alteration. 

In addition, these s"tudies have demonstrated 

that stratigraphy is an extremely important 

structural -tool. Analysis of subsurface samples 

has defined the location of major structural zones 

which were produced during the formation of the 

caldera, but which have since been buried by the 

products of 'the volcanic eruptions. 

COSO 

The need to develop better models of the 

permeability variations and fluid flow patterns in 

a high-temperature fractured reservoir proipted us 

to initiate detailed sampling of core frora the 

Coso geothermal system. Thermal gradient hole 64- 

16 was chosen for -the Initial work because of the 

extensive amount of geothermal veining in it. 

This well is located approximately two km fnom the 

main production area. 

Two stages of geothermal alteration are 

apparent in 64-16. The earlier stage is characterized 

by silica and pyrite deposition in the 

intensely brecciated rocks penetrated in the upper 

half of the well. The second stage is characterized 

by the deposition of calcite. Geothermal 

alteration of -the granitic wallrock has resulted 

in the formation of a highly ordered mixed-layer 

11lite-smectite with 10-20% snoctite. 

Fluid inclusion heating and freezing measurements 

have been performed on calcite from the 

well. Tha inclusions are two phase arxj at room 

temperature consist of a siiall vapor tMbble (10- 

20% by volume) and a low-salinity liquid. No 

evidence of a separate gas phase or of boiling has 

been observed in -the Inclusions. Homogenization

temperatures of fluid inclusions are nearly 

identical to the present equilibrated borehole 

temperatures, and range fncra 15GPC at 325 feet to 

20C^ at 826 feet. Hanogenization temperatures 

near the base of the well average 165°C. The 

salinities of these inclusions average 4500 ppm 

equivalent NaCl (59 measurements). 

Calcite has been isotopically analyzed from 

two depths in 64-16. By oanbining the homogenizaticn 

measurements with the isotopic fractionation 

factors for calcite-water, the O-IB content 

of the hydrothermal fluids can be determined. The 

results indicate that the fluids are 7-8 per mil 

heavier than the local meteoric water and are 

similar to the reservoir fluids. Additional 

isotopic analyses are in progress. Because the 

isotopic shifts in -the fluids are a function of 

the water-rock ratios and hence permeability, it 

may be possible to map variations in permeability 

across tha field using calculations of this type. 

MEAGER CREEK, B. C. 

Drilling for geothermal fluids at Meager 

Mountain, in southwestern Canada, has provided an 

opportunity to study hydrothermal processes and 

fluid flow beneath an active strato-volcano. 

Drill holes have encountered temperatures as high 

as 264*^ in altered crys-talline basement rocks 

that act as the geothermal reservoir. Petrographic, 

mineralogic and trace-element studies 

have been used to establish the paragenetic 

relationships amorg -the several •thermal events 

that have affected tl^se rxx:ks. These relationships 

indica-te that fault and fracture zones, 

steeply dipping dikes, and hydrothermal breccias 

related to recent volcanic activity have focused 

the upward movement of -the geothermal fluids. 

Four chemically distinct groups of thermal 

fluids occur at Meager Mountain. Three are NaCl 

in character and are associated with a well-defined 

thermal anomaly cn the southem flank of the 

volcano. The fourth group consists of NaH003(S04) 

fluids that represent steam-heated ground-waters. 

The fluids range frcm low-temperature and very 

saline with moderate isotope shifts to hightemperature 

and moderately saline with large 

Isotope shifts. 

The chemical and isotopic conpositions of the 

NaCl waters show that little mixing of the 

different fluid 'types has occurred. In contrast, 

extensive fluid mixing is a ocmmon feature of 

highly productive geothermal systems in other 

volcanic terrains. In these productive systems, 

mixing is generally believed to result from 

convectively driven fluid flow in rocks with high 

permeabilities. We suggest that the lack of 

mixing at Meager Mountain reflects fluid flow' 

throjgh a few dLiscrete fracture zones in low 

permeability rocks and that fluid movement is 

driven by tcpographically-ocntrolled head differences. 

Calculated water/rock weight ratios, based 

cn oxygen and deuterium Isotopic shifts of the 

reservoir fluid, range from 0.005 at 123°C to 

0.022 at 1260c. 

SALTON SEA 

The Salton Sea geothermal field is located in 

an active rift zone where greenschist-facies 

metamorphism is currently taking place. The 

field is capped by low-permeability rocks that 

control the distribution of fluid and heat flew to 

a depth of several hundred meters. Chaiiical, 

petrographic, and fluid-inclusion data frcm two 

high-temperature wells show that the composition 

of the brines, fluid flow patterns, and thermal 

characteristics of the caprock changed as the 

geothermal system evol-ved. The caprock in these 

wells consists of two layers. The upper 250 m is 

composed of impermeable lacustrine claystone and 

evaporite deposits. TVie icwer layer consists of 

deltaic sandstones. During the initial development 

of the geothermal systan, downward percolating 

wa'ters deposited anhydrite in the sandstones, 

reducing their permeabilities. Hcmogenization 

temperatures of fluid inclusions in 

anhydrite define a oonductive gradient through the 

caprock. Temperatures reached 245° C near its 

base at a depth 335 m. The salinities of the 

brines rarged frcm 7 to 24 equivalent weight 

percent NaCl. 

Subsequent incursion of high-temperature 

brines into the sandstones resulted in potassic 

al-teraticn, deposition of base metal sulfides, and 

dissolution of anhydrite and calcite. The final 

stage in -the evolution of the caprock records the 

initiation of fracture permeability. During -this 

stage, veins containing quartz, barite, and base 

metal sulfides formed at temperatures ranging frcm 

180°C to 240Oc. 

SURFACE AND BOREHOLE ELECTRICAL M3DELING 

Although none of the geophysical methods maps 

permeability directly, any geological, geochemical, 

or hydrological understanding of the factors 

that control the permeability in a geothermal 

reservoir can be used to help determine geophysical 

methods potentially useful for detecting the 

boundaries and more permeable parts of a hydrothermal 

system. At UURI, we have been developing 

electrical borehole teclviiques to detect arvd map 

permeable zones in -the subsurface, especially 

fractures. 

It is important to understand the differences 

between geophysical well logging and borehole 

gec^3hysics. In geophysical well logging, the 

instruments are deployed in a single well in a 

tool or scnde, and tha depth of investigaticn is 

usually limi-ted 'to -the first few meters from the 

well-bore. Logs such as the gamma-ray, acoustic 

Induction and borehole televiewer logs are 

oarmonly applied in geo-thermal work. By contrast, 

borehole geophysics refers -to those geophysical 

techniques where energy sources and sensors are 

deployed (1) at wide spacing in a single borehole, 

(2) particularly in one borehole and partly on the 

surface, or (3) partly In one borehole and partly 

in a second borehole. Thus, we speak of boreholeto-surface, 

surface--to-borehole ar

The bo'rehDle" eiectricai, techniques are in 

general ppbriy. deyelopal. There' are 'a large;. 

number df ways in which borehole -electrical 

.surveys can be , per-forired and it has been unclear 

which methods are best. At -the s=me; time, 

cxuputer algbrithns "to rtpdel tlie several metlpds 

have rot existed so -that it has, not been possible 

•bo -select amcyig methcxSs prior to' oonmltting to -fehie' 

expense of biiiidirg -a field system and ofcitaining 

te»st data. 

ThB. bb,iecti-yE bf our 'progrcmi is to: 'develop 

arrf. demonsfcratQ -the use of- borehole electrical 

techniques in geo-thermal exploratlcn, reservoir 

delineation ard reservoir exploitation. Qur 

aFôaach: is: 

1. Develop oonputer techniques -to matel -the 

possible borehole 'electorical survey 

systems; 

2. Desigri and oonstruct .a field data 

aoquisitibri sys-feem based- cn "the resul-ts 

of (1); 

3. Acfjuire field data at sites wtece; tiie 

nature and- ext.ent of' perrreabili'ty are' 

known; and, 

4. Develcp .techniques to, interpret field 

daita. 

"Do the present 'tixtie, we have, made oahsiderablei 

progress' en Ttan (;1) above arrf we are row at a 

point where item (2) could be started. We are 

yrarkirg dn, itan (4) cbncurxentiy with (1) slrfce 

.they are closely related. 

Ta date, we have rot. had endigh rfunding 'tx> 

build an appropriate field survey system. 

Hcwever, we have recently negotla-tai. an agreefrent 

with .Utah Internatid-ial, a largb minerals rnlning 

company, for tiê" iise of their well legging 

equipment. With minor nodlflcaticn, this, Equipment 

can be used to test the torelole electrical 

methods we have 'been (teveloping.. Utah Internationa 

1 will also provide technicilan and other inhand 

'support to the project. "mis repressents a 

maj'br breakthrough for us, and we are fateful -to 

them. 

Currently in our -ttesretieal work, the finite 

element method is being a^Jliêd -bs ^the. devplopnent 

of an algprl'thra capable of- modeling (in the 

forward sense) the electrical response of a- tw>dimenslbnal 

(2-D) earth 'excited by' a threedimensicnal 

(3-:D) point souioe. So that -2-b 

• formula.-tlofi can be applied-, the ;prx:tolem is solved 

In the Pour ier-transform •dpmaiji uslihg a, source 

with the s-brlke direc-tlbn trarisfonrrad out. The 

solution obtained vising this source is then 

inverse Fourier transformed to obtain the solution 

for the .3-D squrpe. Finding, ;an refficl^t and! 

accurate method of peirforming the inverse transfonn 

is the task presently: at ,hand, Ul-tlmately, 

the program will enable both surface 'and borefole 

model ing. of carplex 2-D earth structures for 

multiple electrical arrays. 

ThQ Reservoir Definitlcn Prograra at UURI 

approaches the problem, of fracture' definition in 

ocmplek geplogic envixtrinentJs -through .a mul-fcifa'ceted 

approach. This approach emphasizes, 

prediction of the fprmation of .permeabilifcy by 

Analysis' pf -stress fieittei. it .emphasizes processes 

ilgng fractures vrfiich will either maintain 

penreability or destroy it 'through ai'teratieh 

processes. .Arid it emphasizes delineaticn of 

ffactures through geologieal, geochemical and 

gec^jhysical msdelirg.,

ABSTRACT 

Caldera environments are young volcanic 

envirorments in which are often found the type of 

high-silica volcanic rocks that are believed to 

indicate a large magma chamber in the subsurface. 

Such a magma chamber would provide a heat source 

for geothermal systems. Thus, caldera environments 

are fruitful places to look for geothermal 

energy. Fra-n the geoscientific viewpoint, there 

are a. great many questions remaining to be 

ansv;ered about caldera environments. This is 

especially true in evaluating the geothermal 

potential in particular volcanic areas, in 

locating geothermal systems in these areas, and in 

sitirg wells to intersect production zones. The 

objective of the Caldera Reservoir Investigations 

Program is to develop analytical and interpretive 

tools for industry to use in locating and evaluatirg 

geothermal reservoirs within young volcanic 

regions. 

During the past two years, the program has 

concentrated on the Cascades region of the 

rorthwestem U.S. DOE has been performirg costshared 

research with industry consisting of coring 

in specifically chosen areas and in obtaining 

geophysical well logs down hole as well as 

physical and chemical properties of the core. 

These data are beirg ccmpared to surface geological, 

geochemical and geophysical data for the 

purpose of developing and verifying new analytical 

tools and testing existing -tools. Results to date 

indicate that better -tools are needed for use in 

conjunction with surface electrical geophysical 

surveys because seme of the low-resistivity zones 

found from surface surveys correlate with lewtemperature 

hydrothermal alteration rather than 

selectively pinpointing high-temperature positions 

of geothermal systems. A second important result 

is the measurement at three sites of the depth to 

v.'hich cold surface water circulates, which is the 

minimum depth that indus-try must drill to obtain 

reliable heat-flow measurements. 

General Considerations 

BACKGROUND 

The heat source for most high-temperature 

geothermal systems is a body of molten or recently 

cooled rock in the subsurface which has been 

injected frcm great depth into the upper crust of 

the earth. During such intrusion processes, it is 

connon for seme of the molten magma to make its 

•way to the surface and vent as volcanos in the 

form of flows, airfall tuffs and other types of 

deposits. Thus, areas containing young volcanic 

rocks (less than about '1 million years old) are 

generally fa-^-orable for the occurrence of geothermal 

systems. 

CRUIERA RESERVOIR INVESTIGATIONS PROGRAM 

Phillip M. Wright 


391 Chipeta Way, Suite C 


(801)-524-3422 

FTS 588-3422 

Seme volcanic areas contain only basaltic 

magma, a low-silica magma that is lew in viscosity 

and can therefore flow frcm great depth in narrcw 

fracture zones. Such basaltic areas do not 

necessarily indicate the existence of a magma 

chamber close erough to the surface to form a 

geothermal resource. Other volcanic areas contain 

felsic -volcanic rocks which are higher in silica 

content than basalts and which are very viscous. 

Felsic magmas can rot flow frcm depth into the 

crust through narrow fractures because of their 

high viscosity but tend to move upward as fairly 

large bodies -through magmatic stoping or forceful 

injection. The existence of felsic rocks in 

volcanic deposits on the surface is, thus, an 

indication (but not proof) of a large magma body 

in the subsurface at depths between about 2 and 10 

km. Scmetimes a felsic magma body will ccme near 

enough to the surface -to degas precipitously, 

resul-tirg in an explosive eruption of a large 

volume of material. The May 18, 1980 eruption of 

Mt. St. Helens was a small-scale example of such 

an occurrence. Subsequent collapse of the surface 

Into the volume previously occupied by the magma 

body may occur, resulting in a ncminally circulcir 

depression known as a caldera. Calderas are taken 

to indicate that a large silicic magma body 

existed at depth, that seme of the magma may still 

be in place, and that a great deal of heat has 

been brought into the shallow subsurface along 

with the magma body. Thus, caldera environments 

are prime areas for -the occurrence of geothermal 

resources. 

Calderas and volcanos are rather large 

geologic features. The primary problem in 

locating geothermal reservoirs associated with 

these features is in finding zones of open 

permeability near enough to the magma chamber that 

circulating water can be heated to temperatures 

above 150 deg C. Such zones of hydrothermal 

circulation are usually quite restricted in size 

ocmpared to the volcanic features with which they 

are associated. Because of the high cost of 

drilling, industry can not afford to use the drill 

rig indiscriminantly as an exploration tool. 

Sites for exploration drilling must be carefully 

chosen to maximize chances for success. Thus, the 

techniques of geology, geochemis-try and geophysics 

are used to help select the best test drillirg 

locations. 

Each geologic environment has its own set of 

exploration problems, and techniques that vork 

well in some environmen'ts do not work well in 

others. The geologic processes of formation and 

evolution of goothermal systems in the caldera 

envinanment are not well understood at the present 

time. It is difficult for industry to predict 

which of the many exploration techniques should be 

used to find geothermal systems in caldera 

environments.

T1ie Cascades Region 

For the past two years, DOE has been performing 

cost-shared research under the Caldera 

Reservoir Investigations program with geothermal 

developers in the Cascade region of the rorthwestem 

U.S. The Cascade range is being formed by 

a chain of active volcanos that stretches frcm 

Lassen Peak in northem Caiifomia, through the 

great volcanos of Oregon and Washington to Mt. 

Meager in westem British Columbia. Nearly two 

dozen active voicaros attest to the large amount 

of heat being transported into the shallow crust 

in this area. Yet, in spite of the many obvious 

heat sources, high-temperature hydrothermal 

systems have been found at only four sites in the 

Cascades — Lassen Peak and Medicine Lake, 

Caiifomia; Newberry Caldera, Oregon; and, W. 

Garibaldi, British Columbia (see Figure 1). The 

discovered, high-tenperature systems at Lassen and 

Newberry are not candidates for development 

because of the environmental sensitivity of these 

areas. 

0.0 'Op.r.lo,. o'"'*-^C-*~ 

Ctlllornll • ilTNalMA 

J>

'Spu4 lf.i1* 

CCnplilioJt tit* 

TJrtlllfip ConlFic'lor 

Can ?t4CDV«r|f 

Coring Hiilt 

Telft 0*p1h 

Public OsiVniln JUtit 

GEO 

iSSi5.t' PL 

r:bRr\f: STIMMARV 

0-4000 n. '0-4^0?' 1L 

lilEfiilAL. 

>'90'lii: 

loft ) iO" lttn>lpt 1 5/r Iran pFpi Hi jodi 

Timptiiluti 

Cillpir 

Ginînl' Rif 

Hiucron 

TABLE I 

iXt'npMvi' 

I- 

*!««-.47«t' 

ii(ij;-tT(i- 

I

which is the rociprpGal pE resistiyity ih '^pfm-m. 

Deflecticms 'tp' 'tBe- left :cin this log indicate 

higher _ conductivity, i.e;-., lower resiativi-ty.^ 

Coridtictive zones- can' be' seen near 2330 ft, 2890' 

Et, 311G ft, 3350'''ft, 3'4-3d'''ft-, ^3,470 'ft, 3,^9.0' "ft-,' 

3 ^ ft; '3670 it, 3710' ft, 3330' ft and 3S80 6t. 

These -conductive horizons cprrelate. with ;altered 

volcanic? ash and tuffaceous ui'4ts. 

Several of 'the altered zones which 'eijhiblt 

lew resistivi-ty ori the g'eophysical well Idgs wer"e 

chosen for mineralogical study (Wright and 

Nielson, .1-9S6). It was: found that .-the; chief 

alteration' mirieral is- 'calcium ,sfiectite, a clay 

mineral. Hydrpthermal alteration pnoduced the 

'mmi' 

T # rnfl c.

ohm-m. The logs- probably to not represent the 

true:, i>alue o"f the high resistivities bec.ause -the. 

high-resistivity zones are so narrt^j. Minealogical 

studies and laboratory measurenânts of 

resistivi'ty .-were unaertakeh eri cSire, sartp.les fJTCm 

both, the high-resis tivity. portions and the Icwresistivi'fey. 

portions. The results are shewn on 

Table 3, We se^ tl^t typical laboratory, resisr 

tivity values are 11 to 16 ol~m-m for samples, -that 

cbrrespord to logged resistivities of S ohm-m. 

The laboratory njeasurements were made at rpcm 

temperature: .WnereaS: tha downhole 'tempera-ture, was; 

measured at 80 to 95 deg G for this portion of -fche 

hole. Higher in-si'tu temperature would icwei: the 

resistivity t^ a factor of 0.3 to 0.4 for the 

dowiil-ole tempera-tures observed'. VJe Gonclude- -that 

the laboratpry ' measurenerits ph core' samples- ar'eoonsp'hant 

wi-fch, the geophysical well logs. The, 

lower half of Table 3 shows the resul-ts of 

minera lexical analyse 'cn two core samples. Here 

again we found that tKe sample having lower 

resistlvi-fey, contained -an 3ppr^:iable aripunt of 

smectite, -a Icw-'tempiera-ture', hydrpthermal alteratipn 

mineral. We have -tehtat Ively concluded 

"that, in -the Mt. Jefferson area also; Ipw-resistivity 

ancmalies found by 'surface'; resistivity 

surveys do rot necessarily indicate .the presence 

of high-tenperature-^geothermal systems at depth. 

Owm (B-j 

m>, 

UU- 

iSflinr- 

:Shlfti;ii 

IZ» 

tin 

ij(

of the .deefjer thermal regime .in the- area. He.re-we 

see that- in' order to obtain- rel-iabls hea-t-flow 

measuranents, cne would have to- drill below 1220, m 

(4000 ft). 

The Mt, -Jefferson J-ole tof Thermal Power fCb. 

contrasts sharply with the Newberry holes. At 

CPSH-l, the tanperatui-e. is IcCf aiSd slCTtfly iricreasirg 

frcm the surface 'to a depth of about 350 :m. 

Below 350 tn, a^ nearly constant thermal gradient is 

cfeserved, •tiViicatiiigi a cbniiuctive, regime. Ttys 

gradient has an average value in the- Icwer part-of 

tl* hole of 80 deg C per kra. If •this gradient 

persists to- depth below tM' bottom of •the hale, a 

tempera^ture of 200 deg. C would be encountered at 

;2600 m (8500 ft). TTe zor^ of near-surface ,cpld 

water dswnflow exterfe'ônly to 350 m; Presumably, 

the use of heat-flow studies in exploration would 

'be much less eixpeHsive^ for .indus'fcry •to ;carry put 

in the Mt. Jefferscii area ti^n in -the -Newbeu-fy 

-area. 

REFIREHGES 

Bisdorf, R. J.-, 19S3, 'Schlurriberg'er, soundings near 

Newberry Caldera, Oregon: y.-s. Geological 

Survey, Open-File! Repo.rt 83-825. 

Fitterman, D. V,, 1983, Time-dcmain electromagnetic 

sburidings;. pf Newberry Volcarip, 

(Jeschutes GCunty, Oregon: U;S. Geological 

Survey Open-File Report 83-832, 

Fitterman, D. V., Neev, D. K.., Bradley, J. A:, and- 

Groise, e. T,, 19,85, More •tijne-dcmaih elisctrdT 

magnetie soundings- of Newberry Volcano; 

Deschutes Cbunty, Oregon: U.;S.. Geoipgical 

Survey, OE^-Fi-Ie' Report 85^451'. 

Sanmel, E. A., 1981, Results of test drillij^ at 

Newberry vbl.cahp, oregbn: 'Gebthermal 

Resources-Council Bulle^tin, v, 10, n. 11, p. 

3-8. 

lifright, P. M. and Nielson, 0. .L., 19'86, Electrical 

resistivity "anomalies a.t Newterry Volcaro, 

Gr^jii; pompariscsi with alteratibn mineralogy 

in GEO Corehole N-1: Geothermal Resources- 

Gxmcil Bulletin, v. 10, p, 247-252.

CcoiheiJ-iaf RosouTces Council 

APPLICATION OF GEOPHYSICS TO EXPLORATION FOR CONCEALED 

HYDROTHERMAL SYSTEMS IN VOLCANIC TERRAINS 

ABSTRACT 

Phillip M. Wright and Stanley H. Ward 

Earth Science Laboratory 



Exploration for concealed geothermal systems 

in volcanic terrains will require well planned and 

executed programs to succeed and be cost-effective. 

The geologic record indicates that largescale 

hydrothermal convection systeras occur only 

sporadically around plutons, and so a great deal 

more than identifying heat sources will be needed. 

Geophysical surveys can contribute to integrated 

exploration programs if used properly. This paper 

discusses some potential applications of geophysics 

and how it might be integrated into an 

exploration program. 

INTRODUCTION 

Exploration for completely concealed geothermal 

resources has been undertaken to a much 

smaller extent than has exploration for resources 

with direct surface manifestation. By concealed 

resources, we mean those that lack such direct 

manifestations as hot springs, geysers, fumaroles, 

mud pots, hydrothermally altered areas or sinter. 

Many volcanic terrains seem to be characterized 

by abundant potential heat sources, as 

indicated by active volcanism, but by a comparative 

lack of geothermal surface manifestations. 

This is true for the Cascades province of the 

western U.S., as has been pointed out by several 

authors (Brook et al., 1979; Priest, 1983), It is 

also common in other vo'lcanic terrains. In 

Ecuador, for example, the Andes mountains are 

composed of young volcanic features including 

about 30 active or recently active volcanos. Yet 

there are very few surface manifestations indicative 

of large-scale, high-temperature convection 

systems (Instituto Nacional de Energia de Ecuador, 

pers. comrn.). For the Cascade range and for other 

volcanic areas such as Japan, it has been argued 

that high precipitation produces downward and 

laterally migrating cold water that suppresses 

primary surface manifestations (e.g., Oki and 

Hirano, 1974; Priest, 1983), It is also possible 

that there is a relative lack of high-level magma 

chambers associated with some andesitic to basaltic 

volcanic terrains. Lack of magma chambers, of 

course, implies lack of large heat sources at 

shallow depth (5-10 km) to power large, hightemperature 

convection systems. Clearly, it. will 

be necessary to understand these volcanic areas 

423 

TRANSACTIONS. Vol. 9 - PAflT II. Augusl 1985 

better before reliable conclusions about resource 

potential can be made. 

In considering the relationships between magma 

chambers and hydrothermal systems, the geologic 

record from many mining districts tells us 'that 

hydrothermal systems typically occur only sporadically 

around plutons. For example, in the Bingham 

district, Utah, there are extensive outcrops of 

unaltered, unmineralized Last Chance stock and its 

contact with Paleozoic and Mesozoic sedimentary 

rocks, but only the Utah Copper Stock, a later 

Intrusion, produced a large hydrothermal system 

(Peters et al., 1966). In the Valles caldera. New 

Mexico, the known hydrothermal system is associated 

with the resurgent Redondo Dome, but deep 

drill holes at nearby Fenton Hill show that no 

hydrothermal system exists at this location, although 

temperatures are certainly hot enough to 

support convection (e.g.. Smith et al., 1983). 

Hydrothermal convection systems can be expected to 

form around a pluton only if sufficient permeability 

exists or is developed (Norton, 1984). 

Some intrusions or some parts of intrusions produce 

or are otherwise associated with the fracturing 

needed for convection, whereas others are 

not. In exploration for concealed hydrothermal 

resources, we can expect that once a heat source 

is located, the search for an associated hydrothermal 

system will have only begun. 

Economic discovery of hydrothermal systems, 

if they exist around known volcanos, will not be 

an easy task. It is clearly of interest to devise 

cost-effective strategies for their discovery. 

While some would prefer to base exploration solely 

on geology (La Fleur, 1983), we believe that the 

best approach will be a carefully selected and 

integrated mix of geological, geochemical, geophysical 

and hydrological techniques. In this paper, 

we focus on the potential applications of geophysics 

in such an'integrated program. 

CONSIDERATION OF GEOPHYSICAL METHODS 

In this section, we discuss some of the problems 

and promises of commonly used geophysical 

methods in volcanic terrains. 

Thermal Methods 

Thermal gradient and heat flow surveys pro-

Wright et al. 

vide basic data about subsurface temperatures, and 

some program of shallow and deep thermal-gradient 

holes is applied in most systematic geothermal 

exploration programs throughout the world. The 

interpretation of temperature, thermal gradient, 

and heat flow data and the evaluation of resource 

potential from these measurements can be quite 

complex, as discussed by numerous authors (e.g., 

Sass et al., 1981; Rybach and Muffler, 1981). 

Drill holes must be deep enough to penetrate the 

near-surface hydrologic regime, which may be dominated 

by meteoric recharge and lateral flow of 

cold water. In the Cascades, this zone may exceed 

1 kra in thickness. The limitations on the use of 

thermal methods are generally imposed by the cost 

of the drilling program. 

Because it would be unwise to proceed to a 

deep production test in the absence of a known 

temperature anomaly, thermal gradient drilling 

must provide encouragement where surface manifestations 

are lacking. If the holes must be 3000 

feet deep or more, they will be expensive and 

therefore limited in number. The maximum amount 

of pertinent information must be brought to bear 

on siting thermal gradient holes, consistent with 

limited exploration resources. 

Electrical Methods 

Geothermal reservoirs frequently exhibit low 

resistivities due to high temperature, enhanced 

porosity, salinity of the interstitial fluid, and 

alteration of silicate minerals to clays (Moskowitz 

and Norton, 1977; Ward and Sill, 1984). 

Thermal brine and alteration may occur predominantly 

along faults, so these methods raay map 

faults controlling a fractured reservoir. Alternatively, 

they may map a stratigraphic unit that 

contains thermal brines and/or alteration. The 

electrical raethods can also map faults, stratigraphy, 

intrusions, and geologic structure in 

general. Independent of the presence of brine or 

alteration. 

Galvanic Resistivity. This technique can be 

very useful If significant hydrotherraal effects 

occur no deeper than about 2000 feet. For deeper 

occurrences, the tradeoffs between depth penetration, 

loss of resolution of anomalies the size of 

many geothermal systems and difficulty in performing 

the survey make the technique of questionable 

utility. In addition, volcanic areas often have 

high electrode contact resistance, causing low 

transmitted current, and precluding deep exploration. 

AMT/CSAMT. Most reported AMT surveys are 

scalar AMT, that is, only one component of electric 

field and one of magnetic field are measured 

at once (Hoover et al., 1978), It can be demonstrated 

that in layered terrains this scheme is 

adequate for obtaining resistivity structure, but 

if resistivity also varies in either or both horizontal 

dimensions, as it invariably will in volcanic 

areas, scalar AMT is inadequate and is not 

recommended for exploration for concealed resources 

in volcanic terrains. For this task, a 

424 

tensor measurement is needed. 

MT. Magnetotelluric instrumentation incorporates 

the capability to make a tensor measurement, 

that is, to measure simultaneously both orthogonal 

electric field components (E^, Ey) and 

all three orthogonal magnetic field components 

(Hj^, H , H ). This method is generally considered 

to be capable of exploration to depths of tens of 

kilometers, and to be capable of detecting magmas 

directly. Neither of these attributes is true in 

all cases. Although magma is conductive due to 

mineral semiconduction, the amount of contained 

water substantially affects the conductivity, dry 

magraas being much less conductive than wet ones 

(Lebedev and Khitarov. 1964). In geotherraal 

exploration, it is possibly the wet magmas that we 

seek, however, because they have enough volatile 

content to produce the fracturing needed for 

hydrothermal convection. Depth of exploration 

depends to a certain extent on the near-surface 

resistivity structure. Also of great importance 

is the size and other characteristics of the magraa 

body. Newman et al. (in press) have explored 

conditions under which crustal magma bodies can be 

detected. They conclude that if the body is 

isolated, i.e. has broken off from conductive 

raagma at depth, it is more easily detected than if 

it maintains connective roots to the mantle. 

The MT method has been used a great deal in 

geothermal exploration with generally disappointing 

results (Ward, 1983). By far the biggest 

problems appear to be misapplication and inadequate 

interpretation. Most MT data have been 

interpreted using one-dimensional inversion to a 

layered-earth resistivity structure. This method 

is totally inadequate in most geothermal exploration 

and usually produces misleading results. 

Full three-dimensional modeling Is needed. The MT 

method has many subtleties, and must be applied 

with a great deal of care by geophysicists who are 

well experienced. 

CSEM. Controlled-source electromagnetic 

methods have been used as alternatives to galvanic 

resistivity or AMT surveying (Keller and Rapolla, 

1974; 'iCeller et al., 1982), A high-powered CSEM 

systera has been developed and reported by workers 

at Lawrence Berkeley Laboratory (Wilt et al,, 

1981), The primary limitation of these techniques 

to date has been that interpretation methods have 

been limited to the one-dimensional case, Twoand 

three-dimensional algorithms are now becoming 

available, but further development is needed, 

• SP. Spontaneous-potential anomalies over 

convective hydrothermal systems arise frora the 

electrokinetic and thermoelectric effects, which 

couple the generation of natural voltages with the 

flow of fluids and the flow of heat, respectively 

(Sill, 1983). SP surveys have been used successfully 

in certain volcanic terrains. On 

Hawaii, Zablocki (1976) found a large SP effect 

over the East Rift zone. Although these surveys 

are relatively Inexpensive to run, they are also 

difficult to interpret in terms of the nature and 

location of the source area.

General Discussion. There is no wholly 

satisfactory electrical method for exploration for 

concealed resources in rugged volcanic terrains. 

Galvanic resistivity surveys, while relatively 

easy to run and for which interpretation methods 

are reasonably well worked out, lack depth penetration. 

Scalar AMT, which is easy to run and for 

which highly portable equipment is available, does 

not provide enough data to resolve the subsurface 

resistivity structure adequately. The MT method 

Is able to resolve complex structure better, but 

uses very sophisticated, marginally portable 

equipment and requires a highly trained crew and 

complex, sophisticated interpretation. The CSEM 

methods are relatively easy to run but equipment 

is only marginally portable and adequate 

interpretation is only now becoming available. SP 

surveys are easy and cheap but interpretation is 

difficult and ambiguous. In view of the relevance 

of electrical methods to geothermal exploration, 

developraent of electrical equipment and techniques 

specifically for the geothermal environment would 

seem li-ke a wise research investment. 

Gravity Method 

Density contrasts among rock units permit use 

of the gravity method to map intrusions, faulting, 

deep valley fill, and geologic structure In general. 

Regional gravity studies may play a major 

role in understanding the tectonic framework of 

geothermal systems in volcanic environments such 

as the Cascade Range. Couch et al. (1981) note 

that a contiguous zone of gravity lows west of the 

High Cascades in central Oregon defines major 

structural trends and delineates fault zones which 

may localize the movement of hydrothermal fluids. 

Williams and Finn (1982) report that large silicic 

volcanos produce gravity lows when proper densities 

of 2.15 to 2.35 q/atr are used for the 

Bouguer reduction. Other volcanos produce gravity 

highs as a result of higher-density subvolcanic 

intrusive complexes. 

Magnetic Method 

The locations of faults, fracture zones, intrusives, 

silicic domes and raajor altered areas 

are apparent on magnetic data from many geothermal 

prospects. Bacon (1981) interprets major structural 

trends and fault zones from aeromagnetic 

data in the Cascades. A magnetic low occurs over 

a part of the hot-spring area at Long Valley, California, 

and is interpreted by Kane et al. (1976) 

as due to destruction of magnetite by hydrothermal 

alteration. Magnetic data can also be used to 

determine the depth to the Curie isotherm (Bhattacharyya 

and Leu, 1975, among others). These interpretations 

are dependent on many assumptions and 

have serious limitations. It is assumed that 

long-wavelength negative anomalies due to lithologic 

changes do not significantly perturb the interpretation, 

and that the decreased magnetization 

of crustal rocks at depth is due to temperatures 

above the Curie point rather than to deep-seated 

lithologic changes. In addition, because the bottom 

of a magnetized prism is not accurately determined, 

accuracy of Curie-point depth can be poor. 

425 

Seismic Methods 

Wright et al. 

Earth Noise. There is limited evidence (e.g. 

Liaw and Suyenaga, 1982) that hydrothermal processes 

can generate seismic body waves in the 

frequency band 1 to 10 Hz.. Noise also arises in 

such sources as traffic, trains, rivers, canals, 

wind, etc. Liaw and McEvilly (1978) have demonstrated 

that field and interpretive techniques for 

earth noise surveys require a great deal of understanding 

and care. These surveys can provide a 

guide to hydrothermal processes provided that data 

quality is good and careful interpretation is 

done. 

Microearthquakes. Microearthquakes frequently 

are closely related spatially to major 

geothermal systems. Accurate locations of these 

earthquakes can provide data on the locations of 

active faults that raay channel hot water toward 

the surface. Microseismic activity is generally 

episodic rather than continuous, and this characteristic 

may provide a basic limitation to the 

technique in searching for or prioritizing geothermal 

prospect areas. 

Teleseisms. If a sufficiently distant earthquake 

is observed with a closely spaced array of 

seismographs, changes in P-wave traveltime from 

station to station can be taken to be due to velocity 

variations near the array. Traveltime residuals 

are computed as the observed arrival time 

minus that calculated for a standard earth. A 

magma chamber beneath a geothermal system would 

give rise to low P-wave velocities and hence to 

late observed travel times (Iyer and Stewart, 

1977). While one can speculate that relative Pwave 

delays are caused by partial melts or magmas, 

they can also be caused by alluvium, alteration, 

compositional differences, lateral variations in 

temperature or locally fractured rock. 

Refraction. The seismic refraction and 

reflection methods can be used to map the depth to 

the water table, stratigraphy, faulting, intrusions, 

and geologic structure In general. Seismic 

refraction has been used mainly as a geophysical 

reconnaissance method for mapping velocity distributions 

and, hence, faults, fracture zones, stratigraphy, 

and intrusions. These data contribute to 

a better understanding of regional geology and are 

indirectly of use in geothermal exploration. 

Reflection, The seismic reflection method 

provides better resolution of horizontal or shallow-dipping 

layered structures than any other 

method. However, where the structure becomes complicated, 

diffraction of seismic waves occurs and 

makes the task of interpreting structure difficult. 

At Beowawe, Nevada, extensive and varied 

digital processing was ineffective in eliminating 

the ringing due to a complex near-surface intercalated 

volcanic-sediment section (Swift, 1979). 

This problem is typical in volcanic areas. Denlinger 

and Kovach (1981) showed that seismic-reflection 

techniques applied to the steam system at 

Castle Rock Springs (The Geysers area) was potentially 

useful for detecting fracture systems wlth-

training and experience in each of the. earth 

science disciplines be used to form the exploration 

team, even if s.ome, ou:ts1de expertise 'wus,t be 

acquired thro'ugh ebnsultlhg. This will help 

reduce misapplication of techniques, faulty survey 

design and errpnpus .data interp ret it igh and will 

result in more cost-effective exploration. 

Prospect Area SeTectipn [Reconnaissance) 

Our preferences in reconnaissance geophys't.cal 

techniques for volcanic terrains include; remote 

sensing to help, map recentl.y active faults, e-ontacts, 

and other stru'eturfes Md^ aeromagnetic surveys 

to help map subsurface lithologic changes and, 

structure. Acquist.ion -of sateliit'e imagery is 

simple though not inexpensive. Outside, expertise. 

may be needed for appro'pr'iate pro'cessing and for 

interpretation since the average geologist will 

nbt have the required skills,. High-quality "air 

photos are also available for many areas and 

shpuld be acquired and "Jnterpreted at the same; 

time. If rfe'gi.ohal a'eromagnetic data, are no't 

avail'able, one should strongly consider flying ,a 

survey at a data density of about 'one- line per 

mile specifioally for reconnaissance purposes. 

IT regional heat flow studies -and _qravity 

data are a'vailable, they shoul,d. ,be acquired and 

interpret.ed, but we would 'not "generally recommend 

acquisition of such data for reconnaissance purposes. 

None 'of the electfical or :seisiric raethods 

are generally -appropriate at the reconnaissanee" 

stage, although .any ayaiiable information should 

be used. 

Prospe'ct Ranking 

Once^ a list of candidate prospects. Is made., 

one. must assign a relative ranking to each prospect. 

The one geophysical method that should, in 

our o'pini'bn, be applied to each' prospect area, issorae 

form of electr tea 1 -geophys.l cs to rank 

prpsp'ects on the basis of'QCGurRence of conductive 

materials at depth. The specific electrical techniqu,e 

shquld be selected on the basis of access 

and the. exploration model for the specffTc area. 

Areas which .display a resistivity anomaly raay 

further be ranked on the basis of microearthquake 

or earth noi se studi es if desi red, but we do npt 

strongly recomm'ended iti At this po!1nt' it will 

usually be meaningful to drill one or more- thermal 

gradient wel 1 s for the primary purpose of dete'rraifig 

the shallow hydrologic regime. Magnetics and 

gravity usually play only a minor role in ranking 

of prospects. 

:Prospect Testing 

For prospects that pass the screens discussed 

above, it. will gehe'raVTy be- true that additional 

detailed geophysical data will be needed: to help 

site test wells. Assuming that area's with a 

resistivity anomaly have been ranked high for 

drill testing, a more detailed electrical survey 

will probably be needed. One should be guided by 

the results of previous work in the area in se- 

Tecting the electrical raethod and designfrtg the 

427 

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IN-

Thermai genesis of dissGlution caves 

in the Black Hills, South Dakota 

M-. J. BAKALO WICZ Laboruloire Souteirain, Centre National dela Recherche Scmtifyue, 09200'St .Girorts, France 

D. C. FORD Department of Geoâphy, McAfaster University, Hamilton, Ontario L8S4KI Canada 

T. E. MILLER Departinent of G^grdphy and Geblogy. Indiana Sidle Univet-sily, Terre Haute, Indiana 47809 

A, N. PALMER 1 Q^p^^îgf £arthScimces, Shie University eoUege.pneonta, New York,13820 

M. V. PALMER 

ABSTRAGT 

Jewel Gave (118 km of mapped p^sages 

beneath an area of 2,7 km^) and Wind Cave 

(70 km lieneaUi 1.8 km^) are, respectively, the 

fourth and tenth long^ known cave systems 

and fhe •worId?s foremost examples of threedimensional, 

rectilinear networks of solutibnal 

passages. Other caves In the Black Hills 

are similar. They occur in 90-140 m of wellhedded 

Mississippian limestone and dolomite. 

Walls throughout Jewel Gave are lined with 

euhedral calcite spar as much as IS cm thick. 

Wind Cave displays lesser encrustations and 

remarkable calcite boxwork. Since 1938, 

opinion has favored cave excavation by 

slowly circulating meteoric waters in artesian 

confinement similar to that surrounding the 

Black Hitls. 

We believe that the caves were deVeU 

oped by regional themtal waters focusing 

on paleospring outlets in outlying, sand- 

.stones. Four sets of criteria-are evaluated: (1) 

morphological—the three-dimensional, onephase 

maze form havii^ convectional features 

is similar to known and supposed 

ibermal caves in Europe; f2) petrogiaphic 

and mineralogical study of (he: chief precipitates 

showsa record of carbonate solution — 

calcite precipitation con^nant^witb a mode) 

of cooling, then degasing, waters; (3> a 

thermai anomaly at regional hot springs: is 

;hown to'extend beneath Wind Gave, where 

basal lake-water sample sbawchemical and 

isotopic affinities with the thermal waters; 

ind (4) S'^G and' d^Ô measurements place 

j|| suspected paleothermal water precipitates 

in the domain of thermal caldtes reported by 

Bthers and being deposited at the modem hot 

springs. Finally, U-seri» dates show that the 

Wind Gave deposits are Quaternary'and that 

:he cave is still draining. Jewel Gave is truly 

-elict and divorced from themodern thermal 

'round-'water system; its,great calcite.Spar 

iheets are probably older than 1.25-I.§0 Ma. 

INTROriUGTION 

Jewel (3ave,and Wind Cave„in the Pahasapa 

Limestone of the Black Hills, South Dakota,-are 

the world's fourth and tenth tongSt known 

cay^, respectively. They are the foremost examples 

of three-dimensional, rectilinear cavern 

networks. Each displays, in great abundance, 

types of calcite precipitates that are rare in caves 

formecl by direct infiUration of meteoric water. 

Most parts of Jew'el Gave are encrusted with 

coatings of euhedral calcite spar that average 15 

cm in thickness. Wind.Cavedisplaj^ a variety of 

.lesser, coatings and also remarkable, wall and 

ceiling boxwork of composite solutionaWepositipnal 

origin. Shorter caverns are known elscr 

Seological Society of America Biiiletin, v. 99, p. 729-738,'8TigS-, 4 lables, December 1987. 

BUFFALO GAP SPRING 

ll' 

FALL RIVER.SPRINGS 

CASCADE SPRINGS 

where in the Black Hilis; and with few 

exceptions, they appear to be;fragnients of network 

complexes similar to Jewel and Wind 

'Gaves. They contain the ^me exotic fornis of 

; calcite. 

The Black Hills caves are composed of two or 

...three levels of'soiution galleries, most of which 

are disposed in rectilinear arrays. Passage size 

varies greatly, with no tr^d tp increase downstream 

pfjunctions. The multi-storey characteristic 

makes them true threerdimensipnal maês. 

All levels appear to have, developed simultaneously 

in the same phase or sequence of phases. 

This is a rare; phenomenon, two-dimensional 

rectilinear maze caves (thai is, orie storey,, one 

phase) are common, being formed where mete- 

EJ] Precambrian igneous and 

metamorphiG rocks 

^M Gambrian, Ordovician and 

Devonian fofmations 

h-SH Mississippian Pahasapa 

Limestone 

~ rtSl F^nnsylvanian Minnelusa 

Formation arid Permian 

"'s. forrnations 

lin.ll Triassic, Jurassic, and early 

. Cretaceous formations 

;i I Younger sedimentary rocks 

• • Tefttary intrusive rocks 

Figure 1. Geologic map of the Black Hills, showmg locations of described sites. 

729

730 BAiCALQWICZ AND OTHERS I 

one waters are guided itilo a well-joinied and 

soluble timistone either as unifoxm infiltration 

or ai periodic flood waters. Multi-level caves 

with criMcrcKsing galleries are also common, 

but only in cases in which each level represents a 

difTerent phase of development. Normally, these 

are series of passages developed at succeiîvely 

lower levels, displaying dendritic patterns rather 

than rectilinear ones;, pasage size tends to 'increase 

systematically downstream of junctions. 

The probleras posed by the Black Hills caves, 

therefore, are to "explain the deveiopment of 

thKe multi-leyei but singie^phase solution mazes 

pf exceptional extent and to account for their 

exotic mineralization. A majority pf previous 

authors have-advocated variations of a confined 

or artesian flow hypothesis with meteoric waters^ 

!n this paper, we present evidence that both 

the dissolution and the mineralization pf the 

caves are theproduct of rising thermal waters: 

Geologic Setting 

The Black Hills are a dissected domal structure 

of Laramide age (Fig, 1). The core consists 

of rugged mountains of Precambrian igneous 

and metamorphic rocks that were further intruded,by 

igneous, rocks during the early Tertiary, 

Around the periineler, there are cuestas of 

radially dipping Paleozok; and Mesozoic sedimentary 

rocks,, mainly sandstones and shales, 

breached by a few wind and water gaps. By the 

'end of the Eocene, dissection had advanced 

close to the modern base levels (Palmer, 1981). 

Much of the landscape around the perimeter of 

the Black Hills was tben'covered by extensive 

1500 m 

1GO0 m 

500 m 

terrigenous sedioienis of the Oligocene White 

River Group. Therehas been renewed uplift: and 

dissection in the later Tertiary and Quaternary. 

The lowest sedimentary rocks are 20-70 m of 

Garabrian to Mississippian sa'hdstpnes, shalra, 

and arenaceous limestone resting unconforma-; 

bly oh the Precambrian ba^ment (Fig. 2), They 

are siicceeded conformably by the Pahasapa 

Formation, a platform carbonate of Mississippian 

age. It; is 90-140 m thick in the -vicinity of 

the caves. The lower Pahasapa is massive, liniy 

dolomite with prominent joints, favoring'a siihpte 

fissure fo.rm of passage. Middle strata^ in 

which- the principal boxwork is-,found, include 

niedium-bedded limestones and dolomites, locally 

highly fractured and brecciated, with some 

promineiifchert-beds near the top. Passages are 

less regular in^forni, with lower ceiling heights. 

Upfffir strata are, massivie limestones with sparse 

chert nodules. Passages are well rounded. 

The top of thePahasapa Limestone is a Mississippian 

paleokarst that hasa preserved relief 

of—50 ni buried by Pennsylvanian sandstones. 

The paleokarst extends deep into the Pahasapa 

in the fonn of filled solutional clefts, sinkholes, 

and caves. Pennsylvanian: detrital filling vary 

from collapse breccia to' water-laid allochthonous 

sediments, The modem caves primarily follow 

later fracture systems but;ramify into the 

palaeokarst cavities, complicating the modern 

patterns. Reworked pakeofcarst. fill is a major 

component of the detrital veneers in the modern 

cav^. 

The sandstone cover {100-200 m thick) seals 

the paleokarst and the caves: from overhead 

penetration by aJJ but diffuse infiJtratioc of me 

teoric; water, except where recent shallow canyons 

have approached or intetsedM upper 

gallcri^. 

Physiography of the Gaves 

Jewel Cave comprises 118 km of surveyed 

gaUeries contained within an airea of no more 

than 2.7 km^ (Fig, 3). Ii extends between 1,511 

and 1,645 m above sea level in strata dipping a 

few degrees southwest. Thecave is fully drained 

today, except for a few small perched pools, and 

is without flowing water. A nearly ubiquitous 

wail coating of calcite Sfsr is an outstanding 

feature, of this cave (Fig. 4); In the uppermost 

parages, this encrustation has been partly removed 

during at least one solutional episode. 

There is also, sorae local boxwork and a few 

small occurrences of the travertine (stalactite, 

stalagmites) typical of mist caves. The caVe air 

temf^rature is -8,3 °C. 

Wind Cave, contains 70 km of known passages 

beneath an area of 1;8 km^. It extends 

between l,120.and 1,265 m above sea levei. Its 

solutional form is very similar to thai of Jewel 

Gave, except: that the average crOss-sectional 

dimensions are smaller. Spar coating on walls 

are concentrated mainly iii the lowKt levelsand 

are much "thinner than at Jewel Cave. There are 

many othei unusual calcite precipitates, including 

horizontal fins and false floors that appear to 

mark growth at former pond surfaces. Normal 

tfay.ertine dejKisits aiei rare. The famous "boxwork" 

of this, cave is, in-Kale, extent, and complexity, 

probably the Fmesf that has been 

described. It comprises skeletal.structures of vein 

P"^ Precambrian igneous and metamorphie roeks 11-1,11 J Triassic and Jurassic 

WM Cambrian, Ordovician and Devonian 

^3 Mississippian 

Pennsylvanian and Permian 

Cretaceous 

Tertiary and Qtjaternary 

figure 2. Cross section through the Wind Gave area in Ihe southeastern flank ofthe Black Hills. 

.1 

i 

4

JEWEL CAVE 

THERMAL GENESIS OF DISSOLUTION CAVES, BLACK HILLS 731 

Eigiire 3. Maps of Jewel Gave and Wind Gave, drawn at idetttlcal scales, diowmg alt passages [flapped as of 1985. E = natural entiaiice. 

mwL^^^x^-^:-6 

Figure'4. Cross section through calcite wall crust in Jewel Gave, in which it has broken 

way naturaUy from underlying silty textured dolomite. Thickness of crust is 15 cm. 

alcite with later calcite overgrowths (Fig. 5). 

Ills vein calcite has riEsisted dissolution and pro- 

•udes as much.as 1 ra from walls and ceilinp. 

Tie cave air temperature is 11 °C in the upper 

arts, rising to 14 °C in the lowest levels. 

xtcal Hydrology 

The climate in the vicinity of the caves is 

emiârid, with a mean annual rainfall between 

1,60 and 420 mm. Radially draining streams that' 

ise in the wetter central Black Hills become 

nfluent where they cross the sedimentary rocks 

md lose much of their water to inGItratioh, paikularly 

into the Pahasapa. 

The Pahasapa and its equivalents form a 

najor confined aquiferin the rôn. Meat of the 

recharge in'the yicinitygaf'the'caves apjsars to 

be through diffuse infiltration,-except where perennial 

or ephemeral streams sink at rare swallow 

holra. Ground water flows outward from this 

Black ffills, much of it emerging at spring along 

aritieiirfes and fault zones a few kilonieties 

farther out frpm the limestone outcrops. Some 

ground water continue down gentle.hydraulic 

gradients into the deep basinal areas beneath the 

surrounding plains. 

The modem cav^ bear no apparent relation 

to the present surface topography or stream 

patterns. They arc drainesd, relict features, that 

have been iiitercepted localty by shallow canyons 

that" carry seasonal runoff. Wind Cave, 

however, is Iccated along a pateovajley of possible 

Tertiary age, now largely abandoned by flow 

^1 

(Palmer, 1981). Jewel Caveis beside Hell Canyon.the 

major drainage line in the southwestern 

BlackHills; which carries only intermittent flow. 

Despite their juxtaposition to major river valleys, 

there is no clear evidence that' the caves 

were fonned by water frora these sources. 

An important feature, of Wind Cave is the 

presence, of permanent kk«s -at its lowest 

(downdip) end. Similar lakes are not known in 

the.*other Black Hills caves, probably because 

explorers have not yet found them. The-Wind 

Cave lakes are at 1,120 m above sea level, essentially 

the same as the static water level in wells 

that penetrate: the-Pahasapa Limestone farther 

dovradip. This suggests the existence of a very 

flat picEometric, surf'ace vrithin the limestone. 

That, in turn, implies that;there is high perrneability 

(probably in the form of solutional caves) 

extending farther downdip below the water 

level. This piezometric surface is 70 rii higher 

than is Buffalo Gap Spring, 8' kih east of the: 

lakes in Wind Cave. The elevation differehce; 

represeiits' the head required for ground water to 

flow upward to'the spring; through the overlying 

Minnelusa Fprmation. 

The lakes appear to be stagnant backwaters 

fed from below. Their level Kas varied seasonally 

~ 1 nisince they were discovered 20 yr ago. 

Calcite rafts are forming uppn,thern,,the calcite, 

precipitating; onto dust particles Ktded on the 

water surface. Raft formation is indicative pf; 

great hydrauhc stability and the renewal of-a 

supersaturated solution. Rait debris is abundant 

as much as 30 m above ihe nitxiem lakes, U is 

draped'over some helictite bushes, which are 

fragile, subaerial branching calate:spel«)thems; 

very slow, steady riseand fall of'the water level 

is implied by this phenomenon. 

A final relevant feature is the occurrence of 

groups of warm springs at Buffalo Gap, Fall 

River, and Cascade River (F^. 1). Thê springs

732 BAKALOWICZ AND OTHERS 

rise through the Minnelusa Fonnation where it 

is exposed as inliers along local antichnal folds 

on the dip slope. Water temperatures at points 

of emergence are 17-26 °C and do not display 

seasonal variation. Cascade Spring has a mean 

. Figure 5. Idealized cross sections through 

boxwork in Wind Cave. (A) Typical boxwork 

exposed to weathering in upper passages 

above the level of calcite wall crust. 

Most boxwork fins project several tens of 

centimetres but are attenuated here for clarity. 

(B) Projecting veins coated with layered 

calcite wall crust in lower passages. 1 = 

bedrock (friable in A, competent in B); 2 = 

boxwork fins, consisting of recrystallized and 

overgrown pre-cave calcite veins, with ghosts 

of veins now represented by hematite crystals; 

3 = pores in bedrock lined with calcite 

crystals; 4 = "internal sediment" of detrital 

carbonate weathered from higher walls; 5 = 

layered calcite wall crust; 6 = local recrystallized 

wall crust, the layos of which are faint 

or absent (in most cases, on undersides of 

projections). 

discharge of 0.6 m^s"' and is the largest spring 

of any type in the Black Hills. Most of these 

springs deposit abundant travertine in their 

modem channels, which are incised into older 

alluvial deposits. 

The lowest point in Jewel Cave lies 15 m 

above the local water table. The supposed resurgence 

for ground water of this area is 37 km to 

the southeast at Cascade Spring (Rahn and 

Gries, 1973). 

Previous Work 

Davis (1930) attributed the caves to deepseated 

solution of the kind associated with hydrothermal 

ores on the basis of (a) their 

equidimensional maze characteristic, suggesting 

dissolution by slowly flowing waters in the 

phreatic zone, and (b) the spar coatings of Jewel 

Cave, which resemble the Unings in hydrothermal 

veins. 

Later authors accepted the morphologic evidence 

of dissolution by low-velocity phreatic 

water but turned away from the thermal interpretation. 

The earliest hydrogeologic studies (for 

example, Darton, 1918) established the existence 

of a regional, artesian aquifer in the Pahasapa 

Formation beneath the nearby plains in 

Wyoming and South Dakota. Tullis and Gries 

(1938) suggested that the caves were excavated 

by meteoric water circulating slowly through the 

aquifer during the Eocene-Oligocene, soon after 

the uplift of the Black Hills. Howard (1964) 

developed this concept into a more comprehensive 

model in which vadose and water-table 

feeder caves developed updip from the artesian 

mazes. Cave development was not necessarily 

tied to Eocene-Oligocene events and could have 

been much more recent A problem with Howard's 

proposal is that only isolated and poorly 

integrated cave fragments survive in the putative 

feeder areas. 

Deal (1962,1968) published perceptive studies 

of the mineral suites in Jewel Cave, 

recognizing no fewer than seven distinct genetic 

phases: (1) solution by meteoric waters in a confined 

aquifer, as above; (2) partial or complete 

drainage of the caves; (3) return to phreatic conditions, 

with deposition of the principal deposits 

of nailhead spar; (4) drainage of certain cavities, 

as indicated by typical vadose deposits; (5) 

further complete inundation accompanied by 

widespread dissolution of nailhead spar in the 

higher parts of the caves; (6) progressive drainage, 

with deposition of travertine in the upper 

cave and of mud in the lower parts; and (7) the 

modem phase, in which minor travertine deposition 

continues. The final drainage of the known 

cave has long been complete it is a hydrologic 

relict 

We agree vrith Deal that the history of dissolution 

with mineral deposition in these caves has 

been complicated rather than simple. Two of us 

(Bakalowicz and Ford) question the strength of 

the evidence for a vadose phase 2, and clearly, a 

great problem of Deal's sequence is the integration 

of an apparent hot-water inundation (stage 

3) into what is treated otherwise as alternate 

filling and emptying of normal meteoric water. 

White and Deike (1962) used geochemical and 

mineralogical criteria to suggest pressures of 

10-100 atm and temperatures of 150-200 °C 

during stage 3. White (1982, personal commun.), 

however, has since accepted that these 

criteria may be irrelevant and that the minerals 

in question may have been deposited at much 

lower temperatures. 

Palmer (1975, 1981, 1984) pointed to problems 

of explaining the caves by a simple 

confined-flow model. He emphasized that the 

caves are located in a zone in which flow of 

water undersaturated vrith respect to calcite and 

dolomite is possible to and fi'om the Pahasapa 

limestones through the overlying Minnelusa 

sandstone and via flood-water recharge from 

sinking streams. Examples elsewhere show that 

network mazes in limestone are commonly 

formed by either type of recharge. 

Wind and Jewel Cave morphology, although 

unusual, is similar to certain caves of floodwater 

origin. Palmer (1984) suggested that the 

major episode of wall coating might be caused 

by ponding of water in the caves, resulting from 

the regional Oligocene aggradation. Petrographic 

evidence suggesting that the caves formed 

under hydrochemical conditions similar to those 

of hydrothermal ores, however, has turned 

Palmer's opinion away from a standard origin 

(cool water and soil CO2) for the cave 

formation. 

Presented below arc evidences for cave origin 

and development by ascending thermal water. It 

is possible that some mixing with cool meteoric 

waters played a role that is not yet elucidated. 

The evidence derives from geomorphic features, 

from A. N. Palmer and M. V. Palmer's petrographic 

and mineralogical studies, and from isotopic 

measurements of wall rocks, secondary 

minerals, and waters by Bakalowicz, Ford, and 

Miller. 

GAVE ORIGIN BY RISING 

THERMAL WATER 

Morphological Evidence 

In the Western literature, there is little discussion 

of modem and relia hydrothennal solution 

caves. They have been much studied in eastem 

Europe (Czechoslovakia, Hungary, Poland, and '•i

the Soviet Union), however, where Kunsky 

(1950), Jakucs (1977), Rudnicki (1978), and 

Dublyansky (1980) have published English or 

French summaries. Dublyansky listed five criteria 

that strongly indicate a hydrothermal origin. 

One of them—composition of exotic precipitates—is 

considered later in our paper. The 

other four are morphological. 

1. The cave systems lack a genetic relationship 

to the surface topography. 

2. They are largely or entirely devoid of fluvial 

sediments. 

3. The caves in most cases display a threedimensional 

rectilinear maze form guided by 

major fracture systems and, more rarely, by 

bedding planes. This is indkative of excavation 

by slowly flowing ascending waters. 

4. The highest parts of the caves may display 

cupola-form solutional pockets dissolved upward 

into the ceilings. These pockets appear to 

be convectional in origin. Their form is in most 

cases different from that of ceiling and wall solution 

pockets in meteoric-water caves, being 

more multi-faceted but lacking deep penetration 

into a guiding joint 

Jewel and Wind Caves meet all four of these 

criteria very clearly. The first three are noted in 

our introductory description. Cupola-form ceiling 

pockets as much as 10 m in height form 

"The Loft" and other highest places in Jewel 

Gave. They are best seen in "The Fairgrounds," 

stratigraphically the highest part of Wind tZave. 

They are not well developed lower in these 

caves. 

Petrographic and Mineralogical Evidence 

Samples of wall rocks and secondary minerals 

were taken from the caves and nearby outcrops 

for analysis with petrographic microscope, Xray, 

and scanning elearon microscope. Samples 

were obtained under permit from the National 

Park Service and consisted chiefly of small, de 

Hot Spring 

Hoi Brook Spring- 

Higbcf Cascade Spring 

Lower Cascade Spring 

Buffalo Gap Spring* 

Anestfto weu near 

BufliloCip' 

Drip MttH in Jevid Cave 

from inoMciu 

spdectheitts 

I5rip wittr in Wind Qve 

-Ota'teLatein 

Wind an 

•Windjaijllkt" 

in Wind aw 

°C 

16.1 

17.2 

20.9 

20.4 

16.9 

19.0 

9.2 

8.9 

8J 

9.6 

119 

14.1 

poim. 

IWeO penetmes Piliasapa Fonnation. 

pH 

7.01 

7.80 

6.75 

678 

7.18 

7.60 

8.30 

8J0 

8.40 

8.07 

753 

7.90 


tached fragments. A complex sequence of 

solution, alteration, deposition, and replacement 

is revealed in the walls of both caves and will be 

treated in detail in later papers. Only the main 

aspects pertinent to.cave origin are described 

herein. 

The Pahasapa Limestone was subjected to 

continental weathering late in the Mississippian 

Period, as noted. In addition to karst forms filled 

with Pennsylvanian elastics, the carbonate bedrock 

contains highly fractured and brecciated 

zones. Wedging features in the breccia indicate 

an origin due to crystallization and later solution 

of sulfates. Fractures and breccia interstices then 

were filled with hematite-rich calcite, as is 

common during dolomitization. This calcite 

comprises many of the boxwork veins; most of 

them are -100 /im thick, although in breccia 

zones, some reach several centimetres. The veins 

show at least two orders of crosscutting that represent 

different episodes of fracturing. Most are 

truncated by the solutional paleokarst features, 

although some extend upward into Pennsylvanian 

rocks. 

The major phase of cave development occurred 

after the Laramide uplift of the Black 

Hills. Limestone and dolomite were at first dissolved 

at approximately equal rates, as shown 

by somewhat uniform passage enlargement in 

different lithologies, but during the late stages, 

dolomite was selectively removed by water that 

was apparendy close to saturation with respect 

to calcite. Solution of dolomite rhombs aeated 

porosity as high as 90% in the cave walls and 

exposed the calcite veins as resistant fins (Fig. 5). 

Although the calcite veins are much older than 

the cave, their exposure as boxwork is the result 

of cave origin by slow-moving, nearly saturated 

water quite different from that in karst areas fed 

by normal surface infiltration. 

Iron-rich silica replaced much of the remaining 

calcite in the porous bedrock. X-ray analysis 

shows it to vary from opal to microcrystalline 

TABLE I. SUMMARY OF SAMPLE WATERS COLLECTED JANUARY 29 AND 31. 1982 

Ca2* 

(mM/l) 

2.75 

1.76 

14.70 

14.15 

13.25 

1.09 

0.83 

0.S3 

0.6S 

0.94 

0.92 

0J2 

Mg2* 

(mM/l) 

103 

0.94 

175 

3« 

2.10 

0.49 

1.42 

1.73 

ZIS 

0J69 

0.77 

067 

HCO3- 

(m,M/l) 

4.12 

4.20 

3JS0 

4.04 

3.90 

3.20 

3.86 

432 

SJDO 

2.92 

3.49 

3.00 

so,2- 

(mM/1) 

6.66 

0.36 

13.12 

2084 

11.25 

0.03 

0i2 

0.13 

0J2 

0J4 

lO-âttn 

2.5 

0J5 

3.1 

4.1 

IJ 

0.56 

0.09 

0.10 

om 

0.13 

0.22 

0.19 

quartz. The latter is not unconunon in meteoricwater 

caves if there are sources of silica. It is 

an evaporite and thus is limited to frequently 

wetted patches of rock. In Jewel and Wind 

Caves, the silica is rather uniformly distributed. 

This suggests subaqueous deposition, which requires 

a decrease in either pH or temperature. A 

small amount of the silica forms meniscus cement, 

indicating vadose conditions. This may be 

reworked. 

Precipitation of the great calcite spar coatings 

succeeded silica deposition in Jewel Cave. These 

crusts average 15 cm thick and contain as many 

as 20 distinct growth layers (Fig. 4). There are 

no hiatuses or erosion surfaces between layers. 

They appear to be cycUc phenomena. 

In Wind Cave, the calcite crusts occur as 

• overgrowths on the protmding boxwork veins in 

. the dolomitic middle strata (Fig. 5) and as more 

- general wall cover in the lower cave. They average 

only a few millimetres in thickness. There 

are also some pool rim deposits associated with 

them in the lower cave. 

These crusts are subaqueous deposits from 

water brought to supersamration either by degassing 

of CO2 into air-filled upper caves or by 

heating. Degassing evidently occurred in Wind 

Cave. Warming (that was perhaps cyclical) appears 

necessary to account for the great extent 

and volume of the encrustation in Jewel Cave. 

Modem Geothermal and Hydrochemical 

Features 

Rahn and Gries (1973) studied present geothermal 

conditions in the Black Hills, including 

the chemical character of the hot-spring waters. 

In January 1982, we sampled the hot springs, 

artesian water, and the different types of water 

in the caves and obtained the results shown in 

Table 1. The hot-springs data are essentially 

identical to those of Rahn and Gries. Cave waters 

gave results very like those from a larger 

sampling in Wind Cave by Miller (1979). 

'N 

Sl 

caldlc 

-0.14 

0J9 

0.04 

-0.14 

028 

-0.12 

0.45 

0J3 

0J3 

0.14 

0.17 

0.07 

.... 

SI 

dol 

-0.50 

0.65 

-0J2 

-0.83 

-0.15 

-0-49 

1.11 

tM 

\33 

0.14 

029 

0D8 

Sl 

gypsum 

-1J8 

-2.01 

-0.08 

0.04 

-0.14 

-3.19 

-2.13 

-2.71 

-2.47 

-2J6 

i»o 

SMOW 

-16.0 

-14.8 

-15.4 

-15.1 

-14J 

-11.6 

-117 

-12.6 

-113 

-IU 

-111 

113


Rahn and Gries (1973) showed that the Black 

Hills are characterized by two thermal anomalies. 

The first is regional, a slightly higher 

ground-water temperature around the perimeter 

of the Black Hills uplift The second is the more 

sharply defined high-temperature zone around 

the hot springs. In our data, an artesian well 

penetrating through the Minnelusa Formation 

into the Pahasapa Limestone at 2 km from Buffalo 

Gap hot spring yields a geothermal gradient 

of 5 °C/100 m. Air and water temperatures at 

Wind Cave, 7 km from these springs, show a 

gradient of 3.7 °C/100 m, also rather high. The 

thermal anomaly observed al the hot springs 

thus extends beneath modem Wind Cave. There 

are no comparable data for Jewel Cave. 

Schoeller (1962) defined a thermal water as 

one for which the raean temperature is at least 

4° (Celcius) higher than the mean annual surface 

temperature at the spring. In the southern 

Black Hills, this implies temperatures above 

15-16 °C. Table 1 shows that the hot springs are 

only feebly thermal but highly mineralized, especially 

in SO^^". Hot Brook Spring (a tributary 

to Fall River) and Buffalo Gap Spring appear 

anomalous because they could not be sampled 

at their bedrock outlets but were sampled downstream 

after some chemical evolution in the 

open air in cold weather. The other springs are 

weakly undersaturated or at equilibrium with 

respect to calcite and are undersaturated with 

respect to dolomite. Their calculated Pcoi 

shows high values, 1.5-4.1 x 10"^ atm. 

Drip waters in the caves unquestionably represent 

meteoric infiltratioa They are marked by 

high pH and high Mg^* but very little SO^^'. 

They are clearly supersaturated with respect to 

calcite and are presently depositing stalactites, 

but they have a relatively low Pco2 (1-2 x 10"^ 

atm). The artesian well water from the Pahasapa 

Limestone, at a depth of 200 m, is chemically 

most like the drip waters (Pc02 = 6x10"^ atm) 

but is warmed to within the thermal range ofthe 

hot-springs anomaly (19 °C). The lake waters of 

Wind Cave display characteristics intermediate 

between the drips and the artesian sample. They 

are best interpreted as local artesian waters that 

have cooled and degassed in the cave. 

Stable Isotope Evidence 

Water. Meteoric waters dripping into Jewel 

and Wind Caves have average 6 '*0 values of 

-l2,5Voo and -12.l°/oo, respectively, with respect 

to SMOW. Yonge and others (1986) have 

shown that 6'^0 of cave drip waters is equal to 

that of the average annual precipitation in the 

recharge area. The Jewel and Wind values agree 

well with the local precipitation values given in 

Yurtsever and Gat (1981). 

JEWEL WIND 

• o t>edrock and paleoflll 

• euhedral spar sheet 

o lesser wall encrustations 

s s. stalactites and stalagmites 

* & calcite t>oxwork 

DO 

o 

-15 

-U 

a 

, A 

lo O D 

s 

I -to 

.X. 

s 

S 

ss« 

S 

• 

s 

s 

s 

• 

s 

s. 

s 

s., 

s» 

WIND 

I calcite "Ice" 

t = travertine at 

modern hotsprlngs 

5'^qx.POB 

Figure 6. S'-'C and 8^Hi per mil values wrt PDB for wall rock, suspected thermal calcites, 

and normal (meteoric water) speleothems from Jewel and Wind Gaves, plus recent and modem 

hot-springs travertines for Hot Brook and Cascade River, South Dakota. 

"hydrothermal calcite box " 

-•5 

'^C%.POB 

Figure 7. Interpretation of the data plotted in Figure 6, plus data from paleo-hotsprings 

caves at Budapest, Hungary. Envelope 1 contains all boxwork samples from Wind Cave; 2, all 

suspected thermal calcite crusts in lower Wind Gave; 3, all euhedral spars frora Jewel Cave; 4, 

normal stalactites and stalagmites from both caves; 5 is the envelope for subaqueous and 

pool-rim deposits sampled m relict hot-springs caves of Budapest 

POB

SiKiype 


TABLE 1 TESTING FOR EQUIUBRIUM OR KINETIC ISOTOPE FRACTIONATION IN JEWEL AND WIND CAVE CALCrTES 

crusQ of SUI^XBCd 

hydrotncnn&l ongtn 

Wind&nscaldtt 

ausu of supposed 

Wind Cave; modem 

akiu-icc- 

Jcuâve; 

normal suJa£iiie 

Sample 00. 

' JC 0-4 

0-5 

JC 21 

2-2 

2-5 

WC 0-1 

0-2 

0-3 

WC 8-6 

8-7 

WC36-I 

36-2 

36-4 

WC 37-2 

37-4 

WC3S.1 

38-2 

38-3 

WC 21 

JC 11/3-1 

11/3-2 

\oKrJC2-l,2-12-5,»nd so oo = samples measured al lixed intervals along one uamune growth layei. 

t"c 

-155 

-194 

-2.60 

-180 

-167 

-6.82 

-6.14 

-6.55 

-4.72 

-4.89 

-5.88 

-5.90 

-5.94 

-6J2 

-6.15 

-612 

-6.36 

-6.08 

-4.45 

• -8.13 

-6.12 

The hot-springs waters display average S'Ô 

of -15.1700, that is, 3'Voo lighter than the drip 

waters. The possibihty that this depletion is due 

to discharge of "fossil" Pleistocene water from 

cooler climatic phases may be ruled out on 

quantitative grounds. The depletion must be attributed 

to isotopic exchange with depleted 

rocks. 

Calcite. To investigate carbon and oxygen 

isotopic characteristics, 75 samples were collected 

and 150 analyses made by mass spectrometry. 

Samples included- cave wall rock 

(ranging from fresh to highly weathered), paleokarst 

fills, euhedral spars, boxwork and other 

exotic coatings and modem (meteoric water) 

speleothems in the caves, plus travertine and 

water from the hot springs. Results are displayed 

in Figure 6 and interpreted in Figure 7. Seven 

samples of the calcites believed to be of hydrothermal 

origin were selected at random to 

test for isotopic fractionation. In terms of the 

criterion of Hendy (1971), all of these were 

deposited in isotopic equilibrium with the source 

water (Table 2). One ordinary stalactite that was 

tested was not in equilibrium. 

In ordinary speleothems (that is, deposited 

from meteoric waters), 5'^C values are about 

-11 ± 2%o PDB. In effect, the carbon is a oneto-one 

mixture between the carbonate rock 

(5'^G = 0 ± 3%o PDB) and soil GO2 (S'^C = 

-22 ± 5%o PDB). More positive values of S'^C 

(as in afl suspected hydrothennal precipitates 

shown in Fig. 6) are explained by precipitation 

from HCO3" which is enriched in '^C with respect 

to such a mixture. Such CO2 could be 

derived from a magmatic source or by hightemperature 

decarbonation of limestone (Tmesdell 

and Hulston, 1980). 

'/„ wnus PDB 

il'80 

-13J2 

-13.83 

-13-.9I 

-13.92 

-13.91 

-16J4 

-16.04 

-16.24 

-13.76 

-13 J3 

-16.17 

-15.92 

-15.66 

-17.29 

-16.95 

-16.71 

-1648 

-16.23 

-10.94 

-10.58 

-1119 

Equilibrium 

pfeapitauon? 

Yes 

Yes 

Yts 

Yes 

Ya 

Yes 

Yes 

,'^"" 

'»0.yes 

The equilibrium 'Ô concentration in speleothems 

is determined principally by the concentration 

in the source water and the water 

temperature at time of calcite precipitation. In 

Figure 6, it is shown that with few exceptions, 

all suspected hydrothermal calcite deposits in 

Jewel and Wind Caves plot within the domain 

of hydrothermal calcites (Fig. 7), as shown by 

Friedman (1970), Robinson (1975), Barnes 

(1979), and Hoefs (1980). Travertines from the 

Black Hills hot springs are also in this domain. 

Three samples of modern "calcite ice" precipitating 

on the surface of a lake in the bottom of 

Wind Gave have 6**0 values in equilibrium 

with the modem temperahire there but are enriched 

in '^C if compared to normal speleothems 

in the caves. By contrast, an ancient 

"ice" sample 30 m above the lakes has more 

characteristically hydrothermal isotope ratios 

(-6.64%o S^^C and -14.9''/oo 5'80 PDB). One 

small and abenant sample of spar from Jewel 

Cave (-lO.OVoo 5'^0) is now believed to have 

derived from the paleokarst fill. 

The great encrustations of nailhead spar in 

Jewel Cave display little isotopic variation; their 

mean value is 6'80 = -13.8 ± 0.7 (1 a) PDB. If 

the temperature relationship proposed by O'Neil 

and others (1969) is used, their depositional 

temperatures were probably in the range 15 to 

35 "C. The mean value of boxwork in Wind 

Gave is 5'*0 = -18.1 ± 1.6 PDB. This conesponds 

to a temperature range of 30 to 60 °C. 

Wind Cave boxwork has precisely the same isotopic 

range as does the hot-springs calcite in 

Yellowstone Park reported by Tmesdell and 

Hulston (1980). 

Modem dripstone and flowstone speleothems 

that have been deposited by meteoric waters in 

No 

filtrating into the caves are generally quite distinct. 

Some Jewel Gave samples are unusually 

enriched in '^G and depleted in '*0. These may 

be disequilibrium deposits, as in the example 

given in Table 2. Altematively, their feed waters 

may flow over or through the spar sheets as well 

as through isotopically depleted country rock, 

exchanging with these depleted rocks. Wind 

Cave speleothems are not depleted in 'Ô; there 

are no great barriers of spar along the courses of 

their feed waters. Samples of the wall rocks are 

also shifted to lower 6 '*0 and 5'^C values, presumably 

by exchange and some recrystallization 

in the same hydrothermal waters. 

For comparison, Ford collected samples of 

spar, lesser cmsts, and pool .rim deposits from 

caves at Budapest that undoubtedly are of hy- 

" drothermal origin. They display the same deple- 

. tion in '*0 as do the suspected hydrothermal 

calcites in Jewel and Wind Caves (Fig. 7). Some 

. Budapest samples are notably enriched in '^C. 

This is probably due to local, high-temperature 

metamorphism of limestone along some master 

joints during a Miocene volcanic phase that preceded 

cave genesis there (Muller, 1987). Budapest 

cave wall-rock samples also display a strong 

complementary alteration trend. 

In summary, conditions similar to those measured 

at the Black Hills hot springs today (5'*0 

of waters in the range -l4%o to -16%o 

SMOW and temperatures of 20 to 40 °C) will 

readily explain the isotopic composition of most 

of the exotic precipitates sampled in the caves. 

Uranium Series Dating of Gave Calcites 

The caves are devoid of flowing water today 

and are therefore hydrologic relicts. We thus 

cannot measure directly the conditions that 

created them. It is possible that they were 

formed as early as the late Eocene-Oligocene or 

in the mid-Tertiary and thus in origin, might be 

fully divorced from any cunent geohydrolcîc 

or geothermal conditions, although the contrary 

is implied by some of the hydrochemical and 

stable-isotope evidence already discussed. 

Tables 3 and 4 present U-series dates for the 

cave and hot-spring deposits. The modern rate 

of deposition of travertine at the hot springs appears 

to be very rapid; samples are difficult to 

date with great precision because of detrital thorium 

contamination, a problem that is encountered 

in many subaerial tufas. Sample GRO 1 

(which was taken frora an extensive terrace that 

is now distant from the modem hot-spring 

channel of Cascade River), however, can be 

only a few thousand years in age. 

Passages in Wind Cave rise to a maximum 

height of ~ 145 m above the basal lakes. Sample 

WC-t- was a small nailhead spar enaustation


.^mple Descriplioo U 

(ppm) 

WC • 

WC 7 

WC 9 

WC 5 

WC 6 

WC 10 

WC 12 

WC 20 

WC 14 

WC 19 

WC 18 

WC 16 

WC 17 

81062-2 

WC 21 

CRO 1 Oldest luEa tenaoe below Cascade River 

hot springs 

ftote: ^Û/"Û(j = calculated ratio of thee two spodes at nme of co-precipitalion in the calo'te. 

•Age calculated assuming an initial ^^Th/^^-fi, JJ,JQ QJ 1.25. 

Sample [>csaiption U 

(ppm) 

JC 1- 

JC rr 

JC IB 

JC3 

JC 7A/T 

JC 7A/M 

JC 7A/B 

JC 7B 

RL I8A 

RL 18B 

JC MM 

JC UT 

JC IITR 

Nailhead spar, ceotnl cave; — 1.200 m asi 

Wall crust, Boxwoil-Pit: ~ 1.180 m asi 

Vadose flowstone floor, Boxwoil Pit; 

-l.lSOmasI 

Rafts of "aildte ix" draped upon WC 7 

andWC 9 

Cornice grown upon WC 7; probable pod 

surfatx deposit 

Wall otisl. Rescue Pit; -1.155 m asi 

Cornice, Rescue Pit 

Wall crusu-1.145 m asi 

Wall ciusi;-1,135 m asi 

Finc-gnined caldle crtist 10 m above 

Caldle Lake; shows re-solulioo 

Coarse-grained caldte crtisi 10 ra above 

aidte Lake; shows re-solution 

-CaSdtc ice- duped 25 m above lakes 

-atcile ioe" draped 14 m above lakes 

"Calcite toe" dtaped 5 m above bkes 

"Calcite ioc" floating on Caldte Lake; 

1,120 mast 

Nailhead spar crust. 12 cm thick; 

whote-rock age 

Top 2.5 cm of JC 1 

Basal 2.5 cm of JC 1 

Nailhead spar 6 cm thick 

Nailhead spar crust 6 cm thick; lop 1.0 cm 

As above centra! I cm 

As above, basal 1 cm 

Nailhead spar shccl 2-5 cm thick, below 

JC 7A and separated from il by a thin 

red and black silly layer 

Nailheatl spat from lowest pan of cave; 

A 3 base of spar crust 

As above; B = top of spar crust 

Stalactite drapoy (vadose) growing over 

spat, now fallen from wall: 

4-5 cm above base 

Stratigraphic ujp of JC Il;9-I2cm 

above base 

Replicate of JC IIT 

'This sample dispbyed normal magnetic pobriiy, signal very u>'eak. 

taken —80 m above the lakes (Table 3). It indicates 

that the cave was filled with water to or 

above this level before 350 Ka. 23'iu and ^^^V 

are far from equilibrium with each other (compare 

with the Jewel Cave spar samples. Table 

4), indicating that the sample is probably much 

younger than 1.25 Ma. 

The remaining samples were collected between 

the lakes (water table) and Boxwork Pit, 

60 m above. Samples WC 7,10, 20,14, and 19 

are of thin, discontinuous calcite wall crusts oc- 

TABLE 3. 2TV"'U AGES OF SECONDARY CALCTTE SAMPLES IN WIND CAVE AND AT CASCADE RIVER 

3.57 

117 

3.17 

3i79 

7.86 

2.67 

0.532 

162 

1.71 

1.51 

1.14 

1.62 

1-29 

119 

1.41 

U4u/U8u "4u/23«U(, U0Tn,/73lTb U0Th/2Mu 

IJ68 

1J87 

1.580 

1.663 

1.122 

1.670 

1.538 

1.585 

1.736 

1.514 

1.459 

1.600 

1.773 

1.627 

1.810 

TABLE 4. 2»ni/234u ^GES OF SECONDARY CALCnE SAMPLES IN JEWEL CAVE 

•0J7 

0.36 

0.45 

OJO 

0.17 

0.33 

0.49 

0.18 

0.28 

0.18 

7.47 

2.97 

1.72 

234u/23Su 

1.010 ±0-03 

0.922 ± 0.02 

I.OOI ±0.01 

0.998 ± 0.02 

0.922 ±011 

0.972 ± 0.02 

0-980 ± 0.02 

0.986 ±0.04 

1.011 ±0.12 

1.047 ±0.10 

1.078 ±0.01 

1.173 ±0.02 

1.170 ±0.02 

1157 

1035 

1114 

1.189 

1284 

1.665 

1101 

1421 

1.922 

1.706 

1.600 

1.773 

1.627 

1.817 

33 

540 

134 

60 

no 

316 

7 

210 

47 

24 

350 

IJ 

5 

U 

10 

Û/^JSUn »hT,/"2Tb 

1.001 

I.I 19 ± 0.02 

1J33±0.02 

IJ26±0.02 

cuning throughout this height range. They indicate 

that between, broadly, 200 and 250 Ka, this 

lower region of the cave was water filled and 

experienced slow deposition of calcite everywhere. 

Cmst deposition continued, in the lowest 

places at least, until -150 Ka (WC 18). 

Between -200 and 150 Ka, the water table 

appears to have stood close to the bottom of 

Boxwork Pit, with some oscillation through a 

range of several metres or more. This is illustrated 

by the excellent stratigraphic sequence of 

11 

158 

186 

107 

86 

170 

780 

130 

123 

15 

690 

76 

87 

1.099 

0.982 

0.923 

0.890 

0.775 

0.974 

0J71 

0.957 

a984 

0.931 

0.802 

0.014 

0.002 

0.016 

0.032 

2»n./2«u 

1.07 

1.08 

0.912 

1.62 

1.04 

1.02 

1.02 

1.64 

0.99 

1.W 

0766 

0.64 

062 

Age 

(Ka) 

>350 

242 ±16 

205 ± 14 

185 ±12 

154 ±2 

1!0±20 

76 ±5- 

225 ±15 

234 ±20 

208±23 

153 ± 18 

1.6 ±0.4 

0±0.1 

0±0J 

3 ±0.2 

Age 

(Ka) 

>350 

>350 

265 ±30 

>350 

>350 

>350 

>350 

>350 

>350 

>350 

153 ± 18 

106 ±6 

102 ±7 

dates for phreatic crusts, pool rimstones, and 

"calcite ice" shown in Figure 8. The dynamic 

hydrologic conditions implied by this figure appear 

to be the same as those that now occur at 

the modem lakes 60 m below. 

Abundant deposits of "calcite ice" accreted to 

dust particles on the lake surfaces and became 

stranded as the lakes withdrew. The dust nuclei 

create serious detrital thorium problems for dating, 

but preliminary results suggest that the pattern 

of slow lake-level fluctuations superim- 

5 

po 

CO 

2/ 

hii 

lo 

St: 

in 

SC 

m 

or 

m 

sil 

m 

P' 

lh 

th. 

it 

lo 

se 

Pl 

ai 

ai^ 

ol 

2? 

th 

to 

i\if 

rc 

J 

Cf

sed onto a longer term lowering are 

itinuing (samples WC 16,17,21, and 81062- 

Table 3). 

These U-series results for Wind Cave are 

;hly consistent They show that at least the 

ver half of the cave has been in a phreatic 

te with warm-water calcite precipitation dur- 

; the past 250,000 yr or less. Most or all of its 

utional excavation could have cxxurred imdiately 

before crust deposition. The lowest 

e-third of the explored cave (lying below the 

lin boxwork zone) has drained as a backwater 

ce -200 Ka and continues to do so today. A 

)re comprehensive dating study is now in 

igress to elucidate the details there. 

Jewel Cave stands 400 m higher in elevation 

in does Wind Gave and is much farther from 

: modem hot springs. It is to be expected that 

las been relict for a longer period, even in its 

vest parts. This is clearly borne out by Uies 

analyses of the great spar sheets. Our samng 

included spars from high, intermediate, 

d low sites in the cave. If sample JCIB is set 

de as abenant (Table 4), all specimens are 

ler than 350 Ka in age, the limit of the 

Th/^^-lu method. The ratio ^V/^^Û is less 

in or equal to unity. This is in marked contrast 

Wind Gave. We have no means of estimating 

! initial ^Û/^^^l) ratio in spar sheets at 

ivel Cave. The lowest modem ratio is 0.922, 

corded in the stratigraphic tops of samples 

!1 and JG7A. If it is assumed that this ratio 

rresponijs to an age of 350 Ka (it cannot be 

unger), then a ratio of 1.00 ± .01 would rep 


resent a minimum age of 830 Ka. The bases of 

the Jewel Cave spar sheets are most probably 

older than 1.0 Ma in age. 

The remanent magnetism of sample JCl was 

measured. The polarity was normal, but the signals 

were very weak; no age inferences can be 

drawn from the data. 

As noted, there are very few normal (raete- 

' orie water) calcite speleothems in these caves. At 

Jewel Cave, one of the most massive (and presumably 

older?) examples had fallen and shattered. 

Samples taken from its stratigraphic 

middle and upper parts are 150-100 Ka. 

At Jewel Cave, the spar sheets are ancient, 

and their deposition could have been completed 

before 1.0 Ma. Much ofthe cave may have been 

drained at that time. If that is the case, there has 

been remarkably Uttle development of overhead 

infiltration routes into these empty voids during 

the past 1 m.y. because even comparatively massive 

stalactites are quite young. 

DISGUSSION AND CONCLUSIONS 

The evidence we have presented suggests that 

the large network caves of the Black Hills were 

formed by C02-rich waters that were heated 

and that ascended through the Pahasapa Formation. 

Most or all of the thermal precipitates in 

Wind Gave are of Quaternary age. It is possible 

that the dissolutional enlargement of this cave 

was also limited to the Quaternary, but we suspect 

that it probably began during the Miocene 

or Pliocene. Formation of Wind Cave is com 

Figure 8. ^^*Th/^*'U ages of the general wall crust, a former 

flowstone floor, a waterline fin, and lake "ice" of calcite at the 

bottom of Boxwork Pit, Wind Gave. This is from a field sketch; the 

scale is only approximate. See the text for discusson. 

patible with the geothermal and hydrogeological 

conditions that exist in its local rîon today. 

Waters rose and converged through what is now 

the cave zone en route to spring points in an 

adjoining vaUey. As a consequence of continued 

surface entrenchment, spring positions have 

shifted down dip. The valley is now a dissected 

relict, and the known cave has become a drained 

backwater. It retains a strong thermal gradient, 

and final-stage warm-water precipitates (the 

"calcite ice") are still forming at the modem 

water table in it, where exploration is 

terminated. 

Jewel Cave is significantly older and more 

completely relict. It is not related to the hydrogeological 

conditions prevailing in its region 

today. Nevertheless, we suggest that it was 

formed in the same mode as Wind Cave, by 

thermal waters rising and converging through it 

toward spring positions in an earlier level of Hell 

Canyon. The culminating morphological event 

in Jewel Cave was the dqxisition of the calcite 

spar sheets. They are among the greatest known 

in any cave. We have shown that they are deposited 

from thermal waters probably at some 

time before about 1.0 Ma. 

The caves display a broad tendency to descend 

in stratigraphic elevation in the direction 

of stratal dip. This suggests that the thermal 

plumes were rising with an updip component. 

An igneous heat source within the Precambrian 

rocks is envisionecl, related to the igneous activity 

occurring elsewhere in the Black Hills 

throughout much of the Tertiary. Recharge to 

the systems was probably from infiluation of 

meteoric waters over wiiie areas, a pattern of 

circulation that has been documented in many 

geothermal systems (Dublyansky, 1980; Ellis 

and Mahon, 1977). The position of the Pahasapa 

Formation close to the base ofthe sedimentary 

sequence plus the greater elevation of the 

Black Hills make it unlikely that any significant 

part of the cave discharge consisted of basinal 

fluids from strata beneath the sunounding 

plains.


There were three principal modes of cave development 

(1) solution of limestone and dolomite 

at nearly equal rates by water considerably 

undersaturated with respea to both carbonates, 

which mode was quantitatively predominant, 

(2) seleaive solution of dolomite only, by water 

near to saturation with calcite, and (3) deposition 

of calcite from supersaturated water. In an 

ideal thermal model, all three stages will occur 

simultaneously in a vertical sequence. At any 

fixed P(;o2i 'h^ saturation concentration of dissolved 

carbonate in water increases as the 

temperature decreases. As the themial water 

rises and cools, it acquires or retains solutional 

aggressiveness with respect to both calcite and 

dolomite, regardless of the initial dissolved carbonate 

content If cooling of water is very gradual, 

however, the system can hover near the 

saturation value of calcite and dolomite, preferentially 

dissolving the species that is more soluble 

under prevailing geochemical conditions. 

Decreasing hydrostatic pressure in the rising 

water may allow partial degassing of CO2, 

which sharply reduces the saturation concentrations 

and causes precipitation of the secondary 

carbonates. At most sites observed by Ford in 

the Budapest therraal caves, precipitation was 

intense down to 2 m below the paleo-water 

tables and reduced to zero at depths greater than 

—10 m. Rapid degassing in well-ventilated hills 

best explains such sharp zonation. Wind Gave is 

not so well ventilated (despite its name); slower 

degassing probably explains its poorer zonation 

of precipitates. Simultaneous deposition of the 

spar crust throughout Jewel Cave can be explained 

by a phase of warming, inducing degassing 

within the cave zone, or by a protracted 

backwater phase marked by very slow circulation 

and degassing. 

This mcxlel is highly simplified and must be 

modified to account for details in the history of 

the individual caves. Water levels appear to 

have fluctuated in response to local aggradation 

at springs or to wetter spells during the later 

Tertiary and Quaternary, within the over-all 

lowering induced by regional erosion. As higher 

springs were abandoned, meteoric flood waters 

may have penetrated by way of them, contributing 

to cave enlargement 

Finally, the three-dimensional network pattern 

of the caves must be explained. Their origin 

requires a way of distributing the solutional capacity 

of the water rather uniformly between 

major joints over particular areas of several 

square kilometres or more. We suggest that regional 

and diffuse, heated discharge converged 

upon what became the cave zones, flowing up 

dip in the Pahasapa and ascending through the 

lower formations. Cooling of these waters simultaneously 

throughout the joint nets produced the 

cmcial solutional aggressiveness. Fluctuating 

head within the evolving cave zones (in response 

to varying recharge) and mixing conosion probably 

played subordinate roles. 


We are deeply indebted to the administrative 

staff of Wind Cave National Park and Jewel 

Cave National Monument for permitting access 

to all parts of the caves and the collection ofthe 

rock and secondary mineral samples. The stableisotope 

and U-series analyses were carried out in 

the McMaster University laboratories by Martin 

Knipf and Nicolette Caesar under the direction 

of Ford. H. P. Schwarcz discussed and evaluated 

the results with us; we are also indebted to L. R. 

Gardner and M. Gascoyne for their comments. 

Field and laboratory expenses for Bakalowicz, 

Ford, and Miller were paid from a general operating 

grant to Ford frora the Natural Sciences 

and Engineering Research Council of Canada. 

Bakalowicz's North Araerican sabbatical studies 

were supported by a North Atlantic Treaty Organization 

Scholarship and the Centre National 

de Recherche Scientifique, France. Much of the 

field and laboratory work by A. N. Palmer and 

M. V. Palmer was supported by the Wind Cave 

and Jewel Cave Natural History Association. 

The Speleological Society of Hungary graciously 

guided Ford through representative 

caves at Budapest and permitted collection of 

samples for comparison. 

REFERENCES CTTED 

Barnes, H. L, ed., 1979, Geochemistry of bydiotbennal ore deposits: New 

York, Wiky, 798 p. 

Darton, N. H.. 1918, Aitesiao water in die vicioity of the Bladi HiQs, South 

Dakota: US. Geological Survey Water-Si^y Paper 428,64 p. 

Davis, W.M., 1930, Origin of limestone caverns: Geological Society of America 

BuUetin. v. 41. p. 475-648. 

Deal.D.E., I961Geok)gyof Jewel ave Natiooal Monument. Custer County, 

South Dakota, with special reference to cavera fonnation in Ihe Black 

Hills IMS. IhesisJ; Laramie. Wyomiog. Um'vcrstty of Wyoming, 183 p. 

1968. Origin and secondary mincnliralioo of cavb in dte Black Hills of 

South Dakoui, U.S.A.; Intemational Confess of Spdoology, 4th, Yugoslavia, 

Proceedings, v. 3, p. 67-70. 

Dublyansky, V. N.. 1980, Hydrothermal koist in the alpine folded bell of 

southem pans of U.S.S.R.: Ktas i Spehnlogia (Poland), v. 3(12). 

p. 18-36- 

EUis, A. J., and Mahon, W.AJ., 1977, Chemistry and geotherma] systems: 

New York. Academic Press, 392 p. 

Friedman, 1.. 1970, Some investigations of the depoeition of invenioc from hot 

sprints 1. Tbe isolopicchemistryofa travcnineHjcpositing spring: Geodiimica 

el Cosmochimica Acta, v. 34, p. 1303-I3I5. 

Hendy, C H.. 1971, Tlte isotopic geochemistry of spdeotbems.). Tbe calculation 

of the eifects of different modes ^ formation on Uie isotopic oompositioo 

of spdeothems and their applicability as pakodimatic 

indicatot^: Geochlmica et Cosmochimica Acta, v. 35, p. 801-824. 

Hoefs, J.. 1980, Stable isotope geochemistiy; Berlin and New York. Springa- 

Vcrtag, 208 p. 

Howard, A. D., 1964, Model for cavern development under artesian ground 

water flow, with special reference to the Bbck Hills: Natiooal Spdeological 

Society Bulletin, v. 26, p. 7-16. 

- Jakucs, U, 1977. Morphogeneiics of karst regions: Variants of karst evoludon: 

Butlapest. Hungary, Akadetniai Kaido, 284 p. 

Kunsky. J.. 1950, Kras a Jeskyne: Prague, Ciecfaoslovakia, Academia Praha, 

163 p. (French translation by Heiotz, Service Informatioo Geol., 

BROM, no. 1399,1958, Kant el groltcs.) 

Miller. T. E, 1979, Sampling of tbe atmosphere and carixioate aquifa al Wind 

ave. South Dakoui; Wind Ove National Padt Open-File Repoit, 

lip. 

Multer, P., 1987. Hydrothermal paleokaisl m Hungai>, in Bozak, P, Ford, D. 

C, and Gtazek, J., eds., Pakokaisi; a worid review: Amstenbni, the 

Netherlands, Academia Pmha/Elsevicr, (in press). 

O'NdL J. ft, Clayton. R. N., and Mayeda. T., 1969, Oxygen isotope fracdonalion 

in divalent metal carbonates: Journal ot Chemical Physics, v. 51, 

p. 5547-5558. 

Palmer. A. N., 1975, Tlie origin of mare taves: National Speledogictd Sodety 

Bulletin, v. 37. p. 56-76 

1981. Tbe geology of Wind Ove; Hot Springs, SouUi Dakota, Wind 

ave Natural History Association, 44 p. 

1934. Jcwd Cave—A gift from the past Hot Springs, South Dakota, 

Wind ave/Jcwel ave Natural History Asxidatioo, 41 p. 

Rahn. P. H, and Gries, J. P, 1973, Laip; springs in die Black Hills, South 

Dakma and Wyoming: Soudi Dakota Geological Survey Repon of 

Investigaiions 107. 46 PL 

Robinson, B. W.. 1975. Carbon and oxygen isotope equilibria b hydrodiemul 

caldtes: Geochemical JoumaL v. 9, p. 43^46. 

Rudm'cki, J., 1978. Rote of convection in shaping subterranean karst forms: 

Kias i Spelcologia (PolandX v. 2(11), p. 91-101. 

Scbodler, H.. 1961 Les eaux souterraines: Paris, France, Masson, 642 p. 

Truesddl. A. H.. and Hulsusn, J. R., 1980, Isotopic evtdcooe on enviionmenis 

ofgcotbermal systems, in Fritz, P., and Fomes, J. C, eds.. Handbook of 

environmental isotope geochemistry: The lertcstrial environment: The 

Hague, UK Netherlands, Elsevier, p. 179-226. 

Tullis, E. L, and Gries, J. P.. 1938, Bladl Hills caves: Black HiDs Engineer, 

V. 24. p. 233-271. 

White. W. B., and Deike. G. H., 1961 Secondary mineralization in Wind 

ave, Soudi Dakota: National Spdeologital Sodety Bulletin, v. 24 (2), 

p. 74-87. 

Yonge, C J, Foid, D. C. Gray. J., and Sdiwarez. H. P, 1986. SlaUe isotope 

studies of cave seepage water Chemical Geology (Isotope Geoscience 

Section). V. 58, p. 97-105. 

Yurtsever, Y, and Gat, J. R., 1981. Atmospheric waters, in FonL J. R.. and 

Gooliantinj, R.. ttis.. Stable isotope hydrobgy: Oulerium and oxygen 

18 in die water cycle: International Atomic Energy Agency (Vienna) 

Technical Repom Series 210, p. 103-141 

MANtjst:RiFT RrfEi^-ED BY THE SOCIETY MAitGi 31,1986 

REVIS£D MANUS(3UPT RECEIVED FEBRUARY 11,1987 

MA.VUSCBIPT ACCEPTED AMUU 17,1987 

Printed in USA.

Ceothermal Resources Council 

RADON EMANOMETRY IN GEOTHERMAL EXPLORATION OF VOLCANIC ZONES 

Luis C.A. Gutierrez-Negrfn 

Comislon Federal de Electrieldad, Alejandro Volta 655, Col 

Electricistas, Morelia, Mich., Mexico. 

ABSTRACT 

Emanometry of Radon on surface of geothennal 

volcanic areas allows to determinate those subsurface 

zones with low amount of sealed geologic 

structures. These non-sealed fractures behave like 

conduits of Radon flow which is used as a pathfinder 

of subsurface geothermal fluids. Radon 

measurements in surface can be made fastly and 

easily, to a low cost, using an appropiate sampler 

and a plastic detector; this can record the tracks 

of alpha particles v/hich are produced by radioactive 

decay of Radon. Such a sampling methodology 

has proved to be useful to measure Radon concentrations 

in Mexico, at the Los Azufres, Michoacan, 

geothermal field, and at the Las Tres Virgenes, 

Baja California Sur, geothermal zone, both in volcanic 

framework. 

INTRODUCTION 

Presence of faults or fractures in volcanic 

zones is one of the most important factors for 

geothermal exploration; however, it is not enough 

to detect fracture evidences but these structures 

must be without filling materia! along their fracture 

planes, in order to act as conduits for the 

probable underground geothermal fluids. 

Measurement concentrations of Radon gas on the 

surface (emanometry), is a good way for taking a 

decision on what structures can be conductors in a 

geothennal zone. Basis is not complicated. Radon is 

a noble and radioactive gas which originates tp 

depth and raises to surface --with no combination, 

mixing nor dilution-- using most expeditous ways. 

In Nature, one of ways is through planes of failure 

or fracture; therefore, if measurements of 

Radon concentrations on surface are the greatest, 

also is detected a subsurface zone with high density 

of fracturing. These zones are the most attractive 

ones since the point of geothennal view. 

There are some ways for measurement of Radon 

concentrations on surface. But one --most simple, 

fast and effective— is making use of radioactive 

properties of Radon. Thus, this gas decays by 

emission of alpha particles whose tracks or impressions 

can be recorded; these tracks are formed when 

an alpha particle meets a plastic detector. Tracks 

have just some 100 armstrongs of diameter, although 

441 

TflANSACTIONS. VOL 9 - PART I. Augusl 1985 

they can be enlarged and then be evaluated by an 

optical microscope. Amount of tracks are directly 

proportional to araount of Radon. 

This sampling method was experimentally carried 

out in the Los Azufres, Mich., geothermal 

field, and in the Las Tres Virgenes, B.C.S., geothermal 

zone, both located at volcanic regions of 

Mexico. In both cases was determinated the amount 

of tracks of alpha particles by area unit and by 

time of exposition; anomalous zones coincided in 

most cases with high potential geothermal areas. 

Thereafter, this Radon sampling method has proved 

to be an useful tool in geothermal exploration, 

eventhough testing should be extended to other 

areas under geological survey. 

METHOD'S BASIS 

Radon has, in Nature, just three isotopes: 

219 Rn, 220 Rn, and 222 Rn, which are products 

from intermediate decay of the radioactive families 

from 235 U, 232 Th, and 238 U, respectively. 

219 Rn, namely Actinon, and 220 Rn, known as 

Thoron, have very short half lives. These three 

Radon isotopes are radioactive themselves and 

decay to isotopic forms of Polonium through alpha 

emission with distinctive energy, together with 

gamma emission. Table 1 shows some nuclear properties 

of Radon isotopes. 

ISOTOPE 

219Rn 

220Rn 

86*^" 

222RV, 

HALF LIFE 

0.03 sec. 

51.5 sec. 

3.83 days 

Table 1.- Radon isotopes. 

ALPHA ENERGY 

7.13 (99%) 

6.52 (0.2%) 

6.28 (99%) 

5.75 (0.3%) 

4.58 (99%) 

4.98 (0.08%) 

GAMMA ENERGY 

0.61 (0.2%) 

0.54 (0.3%) 

0.51 (0.08%) 

When an atom of Radon decays by emission of 

an alpha particle, it can be recorded by a near 

detector; then, the particle interacts with the 

detector and makes on it an atomic damage (track), 

which remains latent and can be seen only under 

an electronic microscope. However, that track can

GUTIERREZ-NEGRIN 

be enlarged to an enough size for optical microscope 

—by chemical attack on detector. 

It was tested four kinds of plastic detectors, 

being all of them polimeric made with cellulose 

nitrate or acetate and having 15 to 600 microns of 

width. One of these detectors was most efficient 

for record of alpha particles tracks; it is commercially 

known as LR-115 and is made by cellulose 

nitrate with 15 microns of width. In addition, it 

was proved several chemical attack conditions for 

enlargement of alpha tracks (etching); best result 

was obtained by using of Sodium Hidroxide to 20%, 

at 50 °C during three hours (Gutierrez-Negrfn and 

Lopez-Martinez, 1983). 

By another hand. Radon isotopes originate to 

depth; owing its greater half life, 222 Radon is 

the sole with probabilities for arrive and be 

detected at surface. But in some cases in situ 

generation of 220 Radon is probable, owing to 

very small amounts of Thorium in soils. This 220 

isotope also decays by alpha particles which could 

be record at the plastic detector; thus, it is 

convenient to reduce the probabilities of recording 

alpha particles tracks from Thoron. 

With that objective, several types of samplers 

were proved, from classic inverted cup sampler 

(Fleischer and Likes, 1979) to new sampler designs 

that were ex^ profeso made; one of these types, 

nameley M-5 (Fig.l), v/as the best. Length of its 

inner tube --25 cm-- is enough for fast decay of 

any emanation from Thoron or Actinon before it can 

get to detector. The intertube place is filling 

with cotton or wool which absorbs humidity that 

could be condensed, and disposable plastic cup 

put on top prevents water infiltrations from surface. 

The M-5 sampler just needs a little 40 cm 

depth hole; therefrom, it can be easily placed by 

just one people without special tools. Furthermore, 

the same sampler --except its detector-- can 

be used again for several times. 

APPLICATION IN THE LOS AZUFRES GEOTHERMAL FIELD 

The Los Azufres geothermal field is located at 

northeastern portion of Michoacan state, 100 km 

from Morelia City, in the central part of Mexico 

(Fig. 2). It extends on an area of 190 square kilometers. 

In this field drilling includes 45 geothermal 

wells, with an average of 1500 m depth. 

About 21 wells are productive and available for 

production of electricity; whole production now is 

near of 1300 steam tons per hour, though electric 

generation in only 25,000 kw. 

Stratigraphical sequence is consisting of volcanic 

rocks, from Upper Miocene andesites to 

Pleistocenic basalts and pyroclastics deposits, 

including rhyolites, tuffs, dacites, glassy domes 

and pumicite tuffs (Gutierrez-Negrfn and Aumento, 

1982). Geothermal reservoir is in andesites. It 

has been considered that structural systems determined 

geothermal fluids circulation at depth, also 

size and boundaries of hydrothermal system itself 

(De la Cruz and Castillo, 1984). 

442 

Fig. 1.- Radon sampler M-5. 

Radon sampling carried out at southern zone of 

field; 175 M-5 samplers were placed --with respective 

LR-115 detectors— spaced at about 150 m 

intervals, forming a network with N-S and E-W 

lines cutting all known structures at that zone. 

21 days later, only 153 samplers were gotten 

—rest was lost. Detectors were etched with NaOH 

under conditions above mentioned. Then, each 

detector was computed under an ordinary optical 

microscope with 470 X enlargement. 

Amount of tracks was expressed in relation to 

area and exposition time, as units of tracks per 

square centimeter and per hour (t/cm2h); figure 3 

shows an histogram with all values. Average value 

was 24 t/cm^h, standard deviation was 16, minimum 

value was 2 and maximum one 83. It is obvious 

that these units do not express real quantity of 

Radon, but determination of its readioactive 

effects is directly proportional to that quantity. 

Furthermore, sampling purpose is to determine 

those areas with more open structures rather than 

absolute amount of Radon. 

Figure 5 pointed out isoconcentration curves

^H—^ 

^ * 

I SAN IGNACtO 

O o 

V ' 

o 

X ^ LAS TR£S VIRGENES 

^^

Figure 6.- Map showing high Radon concentration zones in Las Tres Vfrgenes. 

were expressed in alpha particles tracks per area 

unit and per exposition time unit-- are directly 

related with non-sealed fractures and faults that 

act as conduits. 

2. In geothermal volcanic zones faults and 

fractures driving Radon have high probabilities of 

driving also underground gethermal fluids. Therefore, 

detennination of superficial zones with 

anomalous Radon concentrations allows to help for 

choose the most interesting places for drilling 

exploration. 

3. It is suggested to use the M-5 sampler, 

easily available due to its low cost, uncomplicated 

manufacture and good efficiency, and to use the 

LR-115 plastic detector --which is commercially 

made in some countries. 

4. From the above considerations, is suggested 

also that this methodology of measurements of 

Radon concentrations could be included as a routinary 

method in geothennal exploration of volcanic 

areas. 

REFERENCES 

De la Cruz, M.V., y Castillo, H.D., 1984. Modelo 

geotermico conceptual del campo de Los Azufres, 

Mich. Inf. 13-84, C.F.E. Internal report, Mexico. 

(Unpublished) 

Fleischer, R.L., and Likes, R.S., 1979. Integrated 

Radon monitoring by the difussional barrier technique. 

Report 79CR0020, General Electric. Schenectady, 

N.Y., U.S.A. 

445 


Gutigrrez-Negrfn, A., and Aumento, F., 1982. The 

Los Azufres, Michoacan, Mexico, goethermal field. 

In: J. Lavigne and J.B.W. Day (Guest Editors), 

Hydrothermal Studies. 26th International Geological 

Congress. J. Hydrol., 56, p. 137-162. 

Gutierrez-Negrfn, L.C.A., y Lopez-Martinez, A., 

1983. Concentraciones superficiales de radon en el 

campo de Los Azufres, Mich. Inf. 32-83, C.F.E. Internal 

report, Mexico. (Unpublished) 

Gutierrez-Negrfn, L.C.A., y Lopez-Martfnez, A., 

1984. Emanometrfa de radon en la zona geotermica 

de Las Tres Vfrgenes, B.C.S. Inf. 12-84, C.F.E. 

Internal report, Mexico. (Unpublished) 

Lira, H.H., Ramfrez, S.G., Herrera, F.J., y Vargas, 

L.H., 1984. Estudio geologico de la zona geotermica 

de Las Tres Vfrgenes, B.C.S., Mexico. In: 

Neotectonics and sea level variations in the Gulf 

of California area, a Symposium. Malpica-Cruz et^ 

al. (Editors), Universidad Nacional Autonoma de 

Mex i CO. 

Lopez-Martfnez, A., 1984. Efectos termicos sobre 

detectores plSsticos. Inf. 8-84, C.F.E. Internal 

report, Mexico. (Unpublished)


This geothermal zone is loirated northeasternly 

of Baja California -Sur state (Fig. 2), 35 km 

from Santa Rosalia town. It is ari elongated portion 

from NW to SE, in a 10' square kilometers area, with 

nine thennal places --essentially hot springs, 

fumaroles and hydfothei;ma1 aTteration zones--, and 

superficial temperatures between 58 and 98, °C. 

Las Tres Vfrgenes geothermal zone seems 

tectonically related with >a great transfonn fau.lt 

that extends from the Galif ornia Gulf and penetrates 

into continent; interactfon between this 

fault and a tectonic weak zone with N-S direction 

—which is evidenced by alignment of .Quaternary 

volcanoes— would be responsible for the origin of 

acfi V e ,g eo the rma 1 • sy s tertt ( L i ra ^ aT_., 1984). Locally, 

fossiliferous sandstpnes from Lower PI iocehe 

are oldest outcropping rocks, begining the volcanic 

sequehce at the top of them. It is represented 

by andesitiCi pumicrtic, ignimbVitlG ..and dacitic 

rocfes,. overlapped by Pleistocenic conglomerates 

and alluvion; last eruption of liear Las Tres VTi^genes 

volcano happened in 174.6 (Mooser and Reyes; 

Iven; after Lira et ^._, 1984). 

46 M-5 samplers with LR-115 detectors.were 

placed at intervals of 50G rr, in a ne.twork whose 

lines v/ere,'oriehtated NW-:SE and NE-'SW. After 30 

days, samplers were recovered and tfieir detectors 

were treated, at before mentioned conditions. Not-witHstahding, 

that conditions become: too much 

drastic for this zone, because 'of its high superficial 

temperatures and its great emissipn' of gas 

like HzS; therefore, concentration of NaOH and 

temperature were keep up, but etching times were 

changed, specifically by each detecfor ir order to 

get a residual wi.dth between' 3.5 and 4 microns.. 

This residual width was keep up uniform for all 

detectors, since the amount of observed tracks \s 

a function bf that residual width (Lopez-Martfnez, 

1984). 

After track computing., a correction —v;hich 

was, pbtained as, result of specific test (Lopez- 

Martinez-, 1984)— was applied in order to compens:ate 

tracks destr()yed by high superficial temperatures 

--'an'tieaTirig-- and by emission of HjS. With 

that correction, values become greater than those 

who were obtained at Los Azufres; thenee:, it was 

used an another unit: tra.cks per squaH centimeter 

per minute (t/crr^min). Figure 4 presents an histo- 

•gram with values of 33 detecto.rs --being the rest 

lost during ejtthirg--; lowest value was 0.2 

t/cm'niin, highest ore was 8.9, ,average was 3.3 and 

^standard deviation was. 1.8. Thus,, those values 

higher than.4.1 t'/m^mn were considered as 

anomalous one (Gutierrez-Negri n>and Lopez-Martfnez, 

1984). 

Likewise at Les Azufres?, an interpolation with 

values "for each saiiipTing point was made, and isoyalues 

of t/cmSniint curves --equivalent to superficial 

eoncentratipn bf Radon-- were drawn. Figure 

6"shows these curves and emphasizes three anomalous 

zones fhat have values greater'than 5 t/cm2min. 

These anomalous zones coincide with low resistivity 

anomalies obtained by an electrical -survey at 

Las Tres Vfrg'enes. thence, that zones are most attractive 

for exploration drilling. 

CONCLUSIONS 

1. The results obtained by measurements of 

Radon concentrations" at Los Azufres and Las' Tres 

Virgenes geoth'eriiial sites, both in Mexico, show 

that ânomalous concentrations pf that gas --which 

Fig. 5.- Hap showing high Radon (ipncentration .zones in The Los Azufres .geothermal fieiy. 

444

GEOTHERMAL RESOURCES IN THE WILLISTON BASIN: NORTH DAKOTA 

William D. Gosnold, Jr. 

North Dakota Mining and-Mineral Resources Research Institute 

ABSTRACT 

Temperatures in four geothermal aquifers in 

the Williston Basin are in the range for low and 

moderate temperature geottermal resources within 

an area of aboutl28,000 km in North Dakota.^ The 

accessible resource base is 13,500 x 10 J., 

which, assuming a recovery factor of 0.001, may 

represent a greater quantity of recoverable 

energy than is present in the basin in the form 

of petroleum. A synthesis of heat flow, thermal 

conductivity, and stratigraphic data was found to 

be significantly more accurate in determining 

formation temperatures than is the use of linear 

temperature gradients derived from bottom hole 

temperature data. The thermal structure of the 

Williston Basin is determined by the thermal 

conductivities of four principal lithologies: 

Tertiary silts and sands (1.6 W/m/K), Mesozoic 

shales (1.2 W/m/K), Paleozoic limestones (3.0 

W/m/K), and Paleozoic dolomites (4.0 W/m/K). The 

stratigraphic placement of these lithologies 

leads to a complex, multi-component geothermal 

gradient which precludes use of any singlecomponent 

gradient for accurate determination of 

subsurface temperatures. 

INTRODUCTION 

Geothennal resources in the Williston Basin 

in North Dakota occur as thermal v/aters in at 

least four regional aquifers, i.e., the Inyan 

Kara (Cretaceous), Madison (Mississippian)," 

Duperow (Devonian), and Red River (Ordovician). 

These resources are classified as either moderate 

temperature resources (150° > T > 90°) or low 

temperature resources (T < 90°) (Muffler, 1979). 

Any assessment of these resources must establish 

the temperature, areal extent, thickness, 

chemical properties, and hydrologic properties of 

the aquifers. Previous work by Harris et. el., 

(1980, 1981, 1983) provides information on areal 

extent, thickness, and water chemistry as well as 

temperature data recorded in shallow wells, a few 

heat flow holes, and a large amount of data 

recorded as bottom hole temperatures (BHT) in oil 

and gas exploration wells. The temperature data 

of Harris et. al., (1983) that are relevant to 

the thermal aquifers are given as linear temperature 

gradients calculated from the BHT and mean 

annual surface temperatures. Those data were 

431 

Geolhermal Resources Council. TRANSACTIONS. Vol. 8. Augusl 1984 

used in an analysis of low-temperature goothermal 

respurces in the United States by the U.S. 

Geological Survey (Sorey et. al., 1983a); and 

geothermal resources in North Dakota were estimated 

for two aquife.ijs, the Madison and the 

Inyan Kara as 7.5 x 10^ J. and 2.3 x lO'*^ J., 

respectively. 

Sorey et al.'s (1983a) estimate of 

geothermal resources suggests a major new energy 

resource for North Dakota. However, the BHT data 

used in the resource estimates gave incorrect 

predictions of subsurface temperatures and the 

resource was underestimated by about 50 percent. 

A fundamental problem was that a two-point 

temperature gradient calculation is inappropriate 

for the Williston Basin because there-are large 

differences in thermal conductivity among the 

four principal rock types in the sedimentary 

section. These rock types and their estimated 

average conductivities in S.I. units (W/m/K) ere: 

Tertiary clays, silts, and sands, K = 1.6; 

Cretaceous shales, K = 1.2; Upper Paleozoic 

limestones, K = 3.2; and Lower Paleozoic 

dolomites, K = 4.0. Consequently, a typical 

temperature-depth curve for the Williston Basin 

is a muHi-component curve with slopes differing 

by as much as a factor of four. Each of the four 

rock types has a thickness on the order of a 

kilometer in parts of the basin. A linear 

temperature gradient based cn accurate BHT data 

from any unit within the basin will give an 

inaccurate prediction of temperature in any other 

unit (Figure 1). 

Because the thermal structure of the Williston 

Basin is complex and cannot be represented by 

linear temperature gradient calculations, the 

first goal of this project has been to determine 

accurately the temperatures of the thermal 

aquifers in the basin. The ultimate goal of this 

project has been to reassess the resource in the 

Inyan Kara and Madison aquifers and to extend the 

resource analysis to include the Duperow and Red 

River aquifers. 

SUBSURFACE TEMPERATURES 

Accurate determination of subsurface temperatures 

should be the first objective in assessing 

geothermal resources in sedimentary basins. The 

methods for determining those temperatures have 

\

GOSNOLD 

TEMPEiRAVURc 

(Doq. C) 

FIGURE 1 - Hypothetical temperature-depth curves 

for the Williston Basin in western North Dakota. 

Curve A was computed from heat flov/ and 

stratigraphic data. Curve B was taken from 

bottom hole temperature data. 

differed among the various DOE State-Coupled 

Geothermal Resource Assessment Programs, and the 

most comraonly used method has been to compile and 

analyze the bottom hole temperature data from oil 

and gas wells. Other methods that have been used 

are direct measurement in deep wells and prediction 

of temperatures from heat flow data. 

Because the basic quantity sought in exploration 

for geothermal resources is heat, establishing 

the most accurate method for determining subsurface 

temperatures is crucial for geothermal 

research. 

432 

The accuracy of bottom hole temperatures as 

predictors of subsurface temperatures was questioned 

in the introduction. In that discussion 

it was assumed that BHT data accurately represent 

the temperatures of the formations in which they 

were recorded. Tests of that assumption are 

available from studies where other methods as 

well as analysis of BHT data were used to determine 

subsurface temperatures. For example, 

Gosnold (1982) compared data derived from the 

geothennal gradient map of North America 

(A.A.P.G., 1976) and equilibrium temperature data 

in Nebraska. The temperature gradients differ on 

the order of 10°C/km to 40°C/km and the temperatures 

differ by about 20°C over the study area. 

In this case the equilibrium temperatures are 

categorically higher than the temperatures 

extrapolated from the BHT data. 

The differences between the temperature date 

sets are due to the data and to the correlation 

applied to the deta. The quality of the data in 

the oil fields in Nebraska is not good. Analysis 

of bottom hole temperatures recorded in nine 

different sections in western Nebraska shows 

that, in some cases, about 20 percent of the 

teraperatures have the same value regardless of 

depth or time interval between cessation of mud 

circulation and logging (Gosnold, Eversoll, and 

Carlson, 1982). In these cases, it is suspected 

that the BHT is a guess by the logger rather than 

en actual record. The time of logging is also 

suspect in most of the data. In a total of 

14,000 records, there are fewer than 100 

instances in which recorded logging times are not 

exactly 1 or 2 hours after circulation ceased. 

The problem with the correction to the BHT data 

is that it was based on equilibrium temperatures 

recorded in wells in the Texas Gulf Coast region. 

The gross lithologies and the thermal properties 

of the sediments there are not the same as those 

in the Cretaceous rocks underlying Nebraska. 

Consequently, the constants in the correction 

equation (see Wallace et. al., 1979) do not apply 

to the rocks in Nebraska. 

Uncorrected bottom hole temperatures are, as 

expected, less close to the equilibrium 

temperature data than the corrected data. This 

condition also was demonstrated in the Nebraska 

project where one of the tasks was to produce a 

contour map of temperature gradients calculated 

from uncorrected bottom hole temperature data. 

That map (Gosnold, 1982) is based on about 14,000 

data and vaguely resembles the A.A.P.G. 

temperature gradient map, but it shows little 

agreement with the equilibrium temperature 

gradient map. 

The Denver Basin in Nebraska has a 

multi-component geothermal gradient curve similar 

to that in the Williston Basin. The geothermal 

gradient in the shale-rich Cretaceous section is 

about 50 K/km due to the low thermal conductivity 

of the shales, i.e. about 1.2 W/m/K (Sass et. 

al., 1982; Blackwell et. al., 1981). The 

gradient in • the Paleozoic carbonate section 

ranges from one-third to one-half of that in the

Mesozoic rocks due to the high conductivity of 

the limestones and dolomites, i.e., about 3.0 

W/m/K to 4.5 W/m/K (see Sass et. al., 1981). 

However, for much of the Denver Basin the BHT 

data are based on temperatures recorded in the 

Dakota Group and only one component of the 

temperature gradient curve influences the data. 

This observation is most significant. In this 

case, a tv/o-point temperature gradient curve 

should apply, yet large differences betv/een 

equilibrium temperatures and BHT data exist. 

Therefore, BHT data may not accurately represent 

fonnation temperatures even for the case of 

one-component geothennal gradient areas, and use 

of BHT data in cases where multi-component 

gradients do influence the data seems wholly 

inadvisable. 

An alternate method for determining subsurface 

temperatures is to use a synthesis of heat 

flow, thermal conductivity, and stratigraphic 

data. This method is a direct approach to 

determining subsurface temperatures because it 

addresses the fundamental variables in the 

thennal structure of the crust, i.e., heat flow 

and thermal conductivity. This method was used 

in the geothennal resource assessment of Nebraska 

(Gosnold and Eversoll, 1981; 1982) end its 

accuracy proved to be excellent. Subsequent 

measurement of temperatures in nine wells at 

depths ranging from 1.2 km to 1.8 km in the 

Denver Basin have found actual temperatures to be 

within 2 degrees of the predicted temperatures. 

WILLISTON BASIN 

At least four geothermal aquifers lie within 

the Williston Basin. Accurate determination of 

their temperatures was the first objective in 

assessing the total geothermal resource. Because 

of its better accuracy, the heat flow-stratigraphy 

synthesis method for determining subsurface 

temperatures was used in this analysis of 

the Williston Basin. Consequently, one of the 

significant results of this study is that it 

provides another comparison between the BHT and 

heat- flow synthesis methods for assessing geothermal 

resources. 

The data for the Williston Basin include 

heat flow data from previous studies (Blackwell, 

1969; Combs and Simmons, 1973; Scattolini, 1978) 

and stratigraphic data summarized in the previous 

geothennal studies in North Dakota (Harris et. 

al., 1982). Thermal conductivities of rocks at 

heat flow sites were used as a basis for estimating 

regional conductivities for gross lithologies. 

Although thermal conductivity of a specific 

unit may differ from site tc site, the range 

of variation for one rock type is small comparedto 

the difference in conductivities for different 

rock types characteristic of the Williston Basin. 

For example, the range in conductivity for the 

Paleozoic shales in Kansas is about 0.3 W/m/K 

(Blackwell et al., 1982), the difference in 

conductivity between the Pierre shale and the 

Madison limestone is about 2.5 W/m/K. A 

constraint on the range of thermal conductivities 

433 

used is obtained 

temperature-depth 

temperature logs 

(Figure 2). 

by comparing 

plot with 

taken at 

GOSNOLD 

the predicted 

the actual 

nearby sites 

FIGURE 2 - Comparison of an equilibrium 

temperature-depth log (small dots) with 

hypothetical temperatures calculated from heat 

flow (large dots). 

In the application of this method in the 

Nebraska study, stratigraphic data were taken 

from electric logs for a number of sites within 

the resource area. However, in this study the 

data were taken from a series of structure 

contour maps of the principal rock formations in 

the Williston Basin (Harris et. al. 1982). These 

maps permitted establishment of a regularly 

spaced grid of points for subsurface temperature 

computations. 

Selection of the grid spacing was determined 

from the spacing of available heat flow data, 

which is the quantity most likely to vary from 

site to site. The nature of the temperature 

field arising from a radioactive basement source 

is essentially the same as that of a gravitational 

field arising from different density 

distributions in the basement (Simmons, 1967). 

The simple half-width rules and depth rules that 

apply to gravity data also apply to temperature 

data, and it is reasonable to assume that lateral 

variation in heat flow due to differences in

GOSfJCLD 

bas(?raent. radioactivity should have its shortest 

wave lengths on the order of the thickness pf the 

sedimentary cove"!!-. For the Williston Basin the 

ideal spacing of heat flow data, would be on the 

order of 4 kilorneters,. The actual spacing of 

data fro'rii previous^ studies (see ScattoTini, 1977) 

ranges from 10 tp greater than 100 km- 'and is 

commonly about 40 kilometers. TO form a .grid for 

temperature projections, speculative interpplation 

of the data is necessary. However, 

extrapolation of these widely spaced data to a 

dense grid of 4 kilometers^ -is; unjustified;, and 

the least speculative extrapolation seems'tn "be a 

grid spacing pf about 40^ kilometers. For the 

purpose of portrayal on available maps', a spacing 

corresponding- to 4, townships,, i.e;.-, 24 miles 

(38.5 km) was. adopted. 

RESClURCE ESTlMAfES' 

Temperatures on top of each of the aquifers 

were projetited for e'atzh point in the 9'^W, grid 

using the simple equation for one dimensional 

heat flow 

Q, = K(dT/dZ) '(-Eq, 1) 

where Q i.s heat flow,, K is thermal conductivity, 

dT is the incremental change tn tempei'a'ture for 

an incremental change in depth of dZ.. The 

temperature at any point Z can be calculated by 

T"= To •^ Zi(Q/ki) (Eq.. 2) 

where To is surface temperature, Zi and Ki are 

the thicknesses and thermal conductivities of the 

li overlying layers.. 

Estimates of the niean accessible resource 

base were obtained using the method of Sorey et. 

al. (198,3b), "i.e.. 

qR = p c a, d (j tr) (Eq. 3) 

where qR is- the accessible respurjce base,, pc is 

the voiumetriiC specific heat of the" rock p.lus 

water, .a is the. reservoir area, d is the reservoir 

thickness, t is the' reservoir temperature,, 

and tr is IS^G. This raethod gives an optomistic 

estimate for the resource base because of the 

.large terapefatur'e dr-op that is used. However, 

each use of geothernial v/aters may require differeht 

ampunts of heat extraction, and heat :exchanger 

characteristics' vary widely among different 

types and in different appli'cations. Therefo're, 

it may be better t'o specify a specific 

reference temperature for- purpose of resource 

estimation and let. the potential user' raake 

additional estimates based on the- data and his 

particular neecjs. 

The recoverable resource -can be calculated 

from the, accessible resource base, by considering 

the hydrologic properties" of the aguifers. The 

general approa^^ch of Sprey et. al. (19a3b) could 

be applied to lihe different aqu'ifers in the basin 

using available data on their respective 

hydrologic properties. However, "the general 

434 

conclusion reached by Sorey ,et. al. (1983b), 

i.e., that the recovery factor for large sedimentary 

basis approaches O.OGl, serves as a convenient 

raethod for raaking the resource estiraate. 

In fact, applying this recovery factor to the 

Williston Basin data gives lower estimates for 

the resource than were obtained by Sorey et. 'at. 

(1983a). (See Table 7, pg. 59). 

Apfi.lying "this recovery factor to the data 

obtained in this study gives, estiraates for the 

resource, that exceed the fistimate of Sorey -et. 

el. '{1983a) by about 107 percent for ttie Inyan 

Kara: and 25 ,percent for the Madison. The difference 

for the Madison- is due "only fo the temperature 

differences- used in the calculations. The 

difference for the Inyan Kara is due to teraperaT 

ture differences and to the size of the area 

included in .the estiraate. The' extent' of the 

resource ar,ea can be caTculated by. applying, the 

criterion' of Reed (1983'), i.e., that ;a' resouree 

must have ?'-temperatureê"keeexJing T'r';, where' 

Tr = TIO, -t- .Z,(..25:) (Eg. 4) 

T.IO is mean annual surface -teraperature' plus 10°C 

and Z. is depth to resource". The Inyan Kara 

underlies. Cretaceous shales that have a therraal 

conductivity on the order of 1.2 W/ra/K, assumino 

that the mean heat flow in the basin is 55 raW/m 

the'minimum depth at which the Inyan Kara becoraes 

a resource can be calculated by setting Equation 

2 .equal to Equation 4 ,and solving for Z. For the 

ednditions given above', this depth is 720 meters. 

Methodology 

CONCLUSIONS 

The raethod ,of estiraating subsurface teraperatures 

used 'iri this study is sign'ifiCantly more 

accurate Jhan i's the use of BHT data. Applicat'i'pn 

of the tfeiit flow syirth'e"s'is' ra'e.t'hod- in this 

study relied on the assumption that thermal 

conductivities do npt vary over the study area. 

This assumption is not entirely -Go'rrect. 

Forraa.tipn ?conducti,vities dc vary throughout the 

basin, but the varlatio'ri is' si^gnificantly less 

than the .differences- in conductivities between 

formations. Aonseq.uently,. errors in calculated 

subsurface teraperature due to variation in 

fprmation eonductiyities are significantly less 

than' errors that result frprn appTyirig lineair 

gradients extrapolated from BHT data. 

The heat flow sy'nthesi's method would be best 

applied where actual conductivities are measurêd 

at each grid point. In raost sediraentary basins. 

ttiis'condi tion can be met. Most state geological 

surveys maintain drill core repositories or 

libraries and numerous saraples are available for 

thermal conductivity anaJyses-. It is suggested 

that, a cooperative 'effort- between the state 

geological surveys and the gepthermal laboratories 

at several universities arid the U^S.G.S". 

could lead to accurate temperature analyses of 

most sedimentary basins. It is rec.priinended that 

this type of project be a major component of any 

future national geotherraal pr-pgram. 

^ .

Resources 

This assessraent of geothermal respurces in 

the Inyari Kara, Madison, Duperow,. and Red Riveraquifers 

places'the accessible resource base in 

North Oakota, at 13,500 xir^.J: (table 1). 

.Inj-Jn Kara: 

Madj^n 

Duporow 

Rett River 

Kanf^Lmi Kininum -Reier-Voir RvJerwoir Rfrôurcp 

Meal ' Teuifi. Tt-n^, Arc* " TliicknejV Esftt 

Icmpcf-styi-c --I.C "C (Ji«"-) (IS.) {IS*'" J.) 

Sl- 

63 

Bl 

B7 

S4 

;i7 

!!7 

138 

25 

31 

31 

K 

ija.Mt; 

123,GOO 

126,000 

123,900 

0.051 

i..36S 

O.IOO 

0.150 

1.100 

6. SOO 

•£,2110 

3,600 

Assuming ;.an estimated -recovery factor of 0.001 

for geotherraal waters andg that a- barrel of 

petroleum containE 6,07 x 10 J., the recoverable 

gepthermal resoiii^ce contained within four aquifers 

in North Dakota i| equiva"lent t.o the energy 

cpnta.ined in-2.22 x 10 'bafrets 'df petfoTeuiii. -A 

surpri'sing' result of this study i.s. tha.t the 

quantify of geotherraal energy i'n' the Wittist'on' 

Basin' raay .exceefl the energy that is- present in. 

the form of oil. The po.fent'ial' "impa'ct of "this 

energy resour.c'e on the industrial climate of 

North Dakota should be explored, Qn deptfl 

Technology for utilization of the .geotherraal 

resource directly as a heat .source an'd for 

electric power geherastion w"i'tH binary systems has 

developed to an economical stage. Wheri exploited 

using both production and' re-injection wells, 

this large energy rêsource is a.l raost non-depl et-' 

able and is; nonTpolluting. S'ome possible uses 

fof th'e resour-^ce are: electric power supply, 

direct heating supply., lignite drythg, grain 

Idrying, electric rail sj-^steras, vegetable crops in 

geothermally heated green houses, and fish 

farming: 

ACKNOWLEDGHEriTS 

The author gratefully acknowledges the 

efforts pf Dexter Perki"ns III, whose careful 

re'view significantly imprgved the raanuscript. 

This v/crkwas supported by the- Departraent-, of 

Ene'fgy Contract Nurrbef 0E-FC07-791D12030. 

REFERENCES 

Blackv/ell,, D.O., 1969,, Hea.t-flow deterrainationE 

in th'e Nofthwestern' imited States, Jour. 

Geophys. Res-, v.4, p. 992-1007. 

Bl ackwel Is 0. D., Steele, J. L., .and Steeples,, D. W.. 

1981a. Heat flow'deterrainations iri Kansas' 

and their implicationE for midcontinent heat 

flow patterns (abstract), EOS, v. 62, p. 

392. 

.4-3-5 

GOSNOLD 

Blackwell,. 0".D., ;and .Steele, vl.t., 1981b. Heat 

"flow and gebth'enral potential of Kansas, 

Final report for Kansas State Agency 

Contract 9,49, 69 pp. 

Combs,. J. and Simmons, G., 19,73. TerrestrîaT 

heat-flow deter^rai nations in the 

North-Centrai United States, Jour. Geophys. 

Res. V. 78,. p. 441-461;" " 

Gosnold, W.Q.., 

Usefulness 

assessment 

resources 

Nebraska -, 

Jr. and Eversoll. D,.A., 1981. 

of heat flow data in regional 

of low-temperature geother-mal 

with special reference to 

Geotherraal Resources Council 

Transactions, v. 5, p. 79-82. 

Gosnold, W.O., Jr. ,, Eversoll, O.A., and Carlson, 

M.P., 1982. Three years of gepthermal 

reseanch in NebraskP, 'in Gepthermal Orrect, 

Heat Prograra Roundtip Technical Conference- 

Pifôceedings j v. 1, C.A, Ruscetta,, Editor, 

ESL, University of U.tah, SaTt Lake Gity, 

Utah, p. 147-157. 

Gosnold,. W.D.. Jr., and Eversoll, D.A.,, 1982. 

Geothermal resources of' Nebraska,. 1;500,000 

scale raap. National G'eophysical and Solar 

Terrestrial Data Center, National Oceanic 

and Atraosph'efic Admi his tration, Boulder., CO. 

Gosnold, W.D,, Jr.., 1982. Geothermal resource 

raap,s and bottora hole temperatures., 

Geothermal Resources Council Transactions, 

v.. "6:, p. 45-48;.,' 

Harris, K.L., Winczewski, L.M., Umphrey, B.L., 

arid Anderson,. S.B',* 1980. An evaluation of 

hydrotherraal resources' of North "Dakota. 

Pha s'e 1 Fi rial T ech n ic a 1 Re por t, E. E. S i Bull. 

No. 80-O3-EES-O2, Grand Forks, ND, 176, pp. 

Harris, K.L., Howell, F.L., Winczewski, L.M., 

Wartman,, B.L., ,Uraphrey, 2.1., and Anderson, 

S.B. , 1981., An evaluation of hydrotherraal, 

resouiêes of Nprth pakpta,. Phase M Final 

Technical Report, E.E.S. Bull. No. 

81-05-EE-S-02, Grand Forks, ND, 296 pp. 

Hai-fis, K.L., Howell, F.L., Warfman, B.t., and 

AndeKson, S.B.,, 198:1.' An evaluation "of 

hydrp'tiierraal resources of North Dakota. 

Phase lii' Final Technical Report., E..E.S. 

Bun. No. 82-08-EES-dt, Grand Forks., NO, 210 

pp- 

Muffler, L.J,.p., and Guffanti, M., 1979, 

Assessraent of Geotherraal Resources of the 

United States--1978, in Assessraent of 

Geotherraal Resources oi" the United 

States —1978,. L.P.J. Muffler," editor, 

U..S:.G.S. Circular 790, 153 pp. 

Reed,. M.J., 1933.. Ihtfoduction to Assessment pf 

low' terapeiâture- gepthenna'l resources of the 

United States—1982." U.S. Geological Survey 

Circular 892, p. 1-8.

GOSNOLD 

Sass, J.H., and Galanis, S.P., Jr., 1983. 

Temperatures, thennal conductivity, and heat 

flow from a well in Pierre shale near Hayes, 

South Dakota. U.S. Geol. Survey Open File 

report 83-25. 

Sass, J.H., Blackwell, D.D., Chapman, D.S., 

Costain, J.K., Keeker, E.R., Lawver, L.A., 

and Swanberg, C.A., 1981. Heat flow frora 

the crust of the United States, vn 

Touloukian, Y.S., Judd, W.R., and Roy, R.F., 

ed.. Physical Properties of Rocks and 

Minerals, v. 11-2. McGraw-Hill Book 

Company, pp. 503-548. 

Scattolini, R., 1977. Heat flow and heat 

production studies in North Dakota, Ph.D. 

Dissertation. University of North Dakota, 

Grand Forks, pp. 257. 

Simmons, G., 1967. Interpretation of Heat Flow 

Anomalies. 1. Contrasts in Heat Production. 

Rev. Geophys., v. 5, pp. 43-52. 

Sorey, M.L., M.J. Reed, D. Foley, and J. Renner, 

1983a. Low temperature geothermal resources 

in the central and eastern United States. 

In Assessment of Low Temperature Geothermal 

Resources of the United States - 1982, M.J. 

Reed, Editor, U.S. Geological Survey 

Circular 892, pp. 51-66. 

Sorey, M.L., M. Nathenson, and C. Smith, 1983b. 

Methods for assessing low temperature 

geothermal resources. In Assessment of Low 

Temperature Geothermal Resources of the 

United States - 1982, M.J. Reed, Editor, 

U.S. Geological Survey Circular 892, pp. 

17-30. 

Wallace, R.H., Jr., T.F. Kraemer, R.E. Taylor, 

and J.B. Wesselman, 1979. Assessment of 

Geopressured-Geothermal Resources in the 

Northern Gulf of Mexico Basin, U[ Assessment 

of Geothennal Resources of the United States 

- 1979, L.J.P. Muffler, Editor, U.S. 

Geological Survey Circular 790, pp. 132-155. 

I 4 36

'•- '.*' 

i: 

ABSTRACT 

Ttie Desert Hot Springs Geothermal Resourtê Area 

(GRA) is abxit 14.5 km (9 miles) north of the 

city of Palm Springs, Caiifomia. The noithwestetrly-trending 

Mission Cr&A fault borders 

the GRA on the southwest. Geotherraal water is 

prodtxred frcra the alluvial deposits underlying 

the GRA. 

Chemiiail analyses of water fron 22 walls throughout 

the GRA indicate the geothermally heated 

vrater rorth of the Mission Creek fault is high 

in sodium and sulfate, differing fixra the water 

sampled south of the fault, which is high in 

ciilcium and bicartxsnate. 

The resiHts of the study indicate that meteoric 

water, originating in the San Bernardino Mountains, 

flows southeasterly toward the GRA along the 

Mission Cre

Corbaley and Oquita 

50 sos+cr 

4. 

-f 

n) 

50 

Dl 

-I- 

+ 

o 

l^ » 

• 

3 

2< 

1* 

1 0 2 0 30 40 

HCO! CO5 

3» 

\: • 

.•i 

• • 

so5+cr 

2 

1» 

HCO5 •*- CO3 

50 cr 

:•; 

I.O 

20 

30 

10 

_ 

-t- 

* 

n) 

o 

50 

50 

D> 

It) 

O 

0 HCOi-f CO5-h SO4 50 

COMBINED ISOTHERM MAP 

50 SOS + cr 

0 

wip-1 

3« 

Geothermonetry isotherms were superinposed on 

the isotherms of produced water, yielding a 

map that is useful for determining areas of 

upwelling and directions of fluid flow (Fig. 2). 

The areas of upwelling are assumed to be the 

areas where highest produced-water terperatures 

coincide with highest geothermmetry teirperatures. 

The initial direction of fluid flow 

away frcm the center of upwelling often is in 

the direction of the produced-water isotherms 

radiating fron the center. In sore areas, 

large tenperature differences between the two 

sets of isotherms are an indication that geothermal 

water flows laterally through these 

areas and is cooled faster than the geothernoretry 

indicators can equilibrate. This 

condition aj^jears to arise downslope frcm 

the upwelling centers. 

50 

2. 

1* 

HCO| + CO5 

HCOl 

,—. —,, 

_ ^ '3 

•I 

1 

, 

:4 

2 

50 

Dl 

•0 

O 

50 

2 

-)- 

+ 

t) 

2 

50 

t^ Vi • 

3^ 2 

soi + ci" 

1* 

Hco; C05 50 

" 

Jni . 

SOS 

3* 2» 

co3 + so4-fcr 50 HC05 + coi-fcr 50 

Figure 3. langelier diagrams, showing isolation 

of various ions. Scale represents percentage of 

the reacting vedue. 

110 

The geothemonetry isotherms in anomalies 

identified as A and C generally follow the 

trends of the produced-water isotherms. For 

anenaly A, the tenperature difference between 

the two sets of isotherms varies frcm 0 C at 

the up»«relling center to 25°C at the southem 

end of the anomaly. For anotaly C, the differences 

are about 10 C and 45 C, respectively. 

The elongated patterns of both sets of isotherms, 

combined wi-th the large tenperature difference 

to the siDutheast, indicate that the flow frem 

both ancmalies is primarily to the southeast — 

a direcrtion consistent with the regional hydraulic 

gradient. 

The flow path for anomaly B is not as easy to 

interpret. The small area with the 80 C produced-vater 

isotherm is assumed to be the 

center of upwelling. The pattern of the produced-water 

isotherms suggests i:hat a large 

ccnponent of geothermal water initially flows 

northeasterly and southwesterly for about 1 km 

through channelways (fractures) that bisect the 

lobes of the isotherms in these directions. 

The water flowing frcm anomaly B is undoubtedly 

mixed with water flowing southeast frcm anomaly A, 

as indicated by the change in direction of the 

60 C and 70 C geothermcmetry isotherms. This 

mixing of geothermal waters makes it difficult 

•1 

0> 

2

Table 1. Concentrations in ppn of selected 

ions and silica oxide frem geothermal wells 

in the Desert Hcjt Springs GRA. 

M!li 

ittnbcr 

1 

2 

3 

4 

5 

6 

7 

10 

11 

12 

13 

14 

15 

16 

n 

18 

19 

20 

21 

22 

60 

53 

101 

33 

55 

74 

29 

58 

34 

52 

69 

41 

49 

68 

64 

47 

64 

51 

46 

55 

48 

54 

H 

2 

0 

2 

5 

5 

2 

6 

1 

42 

52 

133 

239 

300 

393 

221 

293 

276 

285 

349 

301 

332 

302 

291 

310 

345 

275 

235 

328 

223 

333 

10 

4 

4 

9 

6 

5 

6 

9 

9 

10 

4 

12 

11 

7 

12 

7 

9 

•~4 

130 

150 

394 

400 

606 

660 

335 

460 

460 

502 

445 

450 

465 

465 

500 

536 

510 

564 

428 

565 

464 

548 

14 

17 

101 

144 

•153 

306 

93 

167 

159 

216 

215 

147 

180 

191 

156 

136 

201 

180 

ISO 

212 

138 

185 

HOOj 

Table 2. Selected geothermcmetry equations 

(Henley, et al., 1984) used in this study. 

Concentrations of Na, Ca, K, and Si0_ are in 

parts per million. 

têothemicineter 

295 

257 

164 

71 

32 

72 

48 

82 

40 

47 

59 

55 

35 

51 

114 

43 

76 

45 

69 

34 

36 

15 

Restrictions 

a. ^jart2-fio ste;«n loss t-C= • -273.15 t = 0-250-C 

5.19-log SiOj 

b. Cuartz-ttiaxlmni u-C- 273.15 I; " 0-250-C 

steam loGS 5.75-loq SiO^ 

c. Chalcedony 

g. Ha-K-Ca 

1032 

t-C= 273.15 t = 0-250-C 

4.69-lcq SiOj 

HaA (Fournier) fC — . -273.15 t > ISO'C 

log (na/K)+1.483 

855.6 

Q. NaA (Truesdell) t-C" 273.15 t > 150-C 

log (HaA)+0.8573 

1647 

log (Ma/l-,)4 /3fog(iCa/Na)*2.06)+2.47 

where .^ = 1/3 

leg (Na/K)* /3£cg(-*a/t'a)-^2-06j+2.47 

wtxire .'3 = 4/3 

2 

19 

17 

21 

15 

21 

15 

19 

26 

45 

32 

23 

28 

34 

45 

21 

56 

18 

59 

13 

47 

Corbaley and Oquita 

Table 3. Produced-water tanperatures measured 

at the wellhead and calculated subsurface temperatures 

for geothermometer equations in Table 2. 

The last column is the average of the two 

geologically most credible results, those 

derived frcm equations (a) and (g). 

Measured 

iitoduccd. 

SiO, 

'2 

:la-K 

"" " 

I

Ctorbaley and Oquita 

"The combined isotherm map (Fig. 2) suggests 

that the ascending geothermal water crests in 

the areas labeled A, B, and C. The pattern of 

produced-water isotherms suggests that within 

anomaly B, some of the geothermal water flows 

to the northeast and seme to the southwest. The 

water, however, soon becores mixed with geothermal 

water flowing southeasterly frcan anomaly A. 

This ccmbined flow is to the southeast, consistent 

vdth the region£il hydraulic gradient. 

The geothermal water that upwells in anonaly C 

also flows to the southeast, consistent with 

the overall flc3w direction. 

ACKNOWI£IXSEMEOTS 

The authors gratefully acknowledge the assistance 

received frcm many individuals, in particulair 

Professor R. Grannell and A. Nation vdio volunteered 

much tiine and assistance. Special -thanks 

are offered to those who reviewed the manuscript. 

SELECTED REFERENCES 

Caiifomia Department of Water Resources, 

1964, Coachella Valley investJ.ga1u.on: 

Bulletin no. 108, 145 p. 

Corbaley, R., Nation, A., and Grannel, R., 

1981, A resource assessment of Desert Hot 

Springs Geothermal Resource Area, California: 

The future of small energy 

resources, UNITAR, McGrav/-Hill, Inc., 

New York, N.Y. 

Ellis,'••A.J., 1970, Quantitative interpretation 

of chsnical characteris-tics of hydrothermal 

systems: U.N, symposium on the developnent 

and utilization of geothermal resources, 

Pisa, V. 2, part 1: Geothermics Special 

Issue no. 2, p. 516-528. 

Foumier, R.O. and Truesdell, A.H., 1970, 

(3iemical indicators of subsurface temperatures 

applied to hot sprinqs waters of 

Yellowstone National Park, I'Jyctninq, USA: 

U.N. symposium on the development arti 

utilization of geothermal resources, Pisa,, 

V. 2, part 1: Geothermics Special Issue 

no. 2, p. 529-535. 

Foumier, R.O. and Truesdell, A.H., 1972, An 

anpirical Na-K-Ca geothermometer for 

natural waters: Geochim et Cosochim Acta, 

V. 37, p. 1255-1275. 

Foumier, R.O., White, D.E., and Truesdell, 

A.H., 1974, Geochemical indicators of 

subsurface tanperatures - part 1; Basic 

assumptions: Journal Research, U.S. Geol. 

Survey, v. 2, no. 3, p. 259-262. 

112 

Foumier, R.O. and Truesdell, A.H., 1974, 

Geochemical indicators of subsurface 

tenperatures - part 2; Estimation of 

taiperature and fraction of hot water 

mixed with cold water: Journal Research, 

U.S. Geol. Survey, v. 2, no. 3, p. 263-270. 

Foumier, R.O. and Rowe, J.J., 1966, Estimation 

of underground tsiperatures frtm the silica 

content of vrater frcm hot springs and vetsteam 

wells: American Journal of Science, 

V. 264, p. 685-697. 

Gastil, R.G. and Bertine, K.K., 1981, Reconnaissance 

study of thermal springs and 

wells and the deposits of recently extinct 

thermal springs in the Peninsular Ranges 

Province of Southem and Baja Caiifomia: 

U.S. Geol. Survey, Geothernal Research 

Program Final Report, Caiifomia Division 

of Oil and Gas, Open-File Inventory, 152 p. 

Gastil, G. and Bertine, K., 1986, Correlation 

between seismicity and the distribution of 

thermal and carbonate water in Southem and 

Baja Caiifomia, United States, and Mexico: 

Geology, v. 14, p. 287-290. 

Geotechnical Consultants, Inc., 1979, Hydrogeologic 

investigation. Mission Creek 

Subbasin within the Desert Hot Springs 

county water district: Report no. S78088, 

Santa Ana, Calif., 59 p. 

Hart, E.W., 1980, Fault rupture hazard zones 

in Caiifomia: Ciilifomia Division of Mines 

and Geology, Special Report no. 42. 

Henley, R.W., Truesdell, A.H., Barton, P.B., 

and Whitney, J.A., 1984, Fluid-mineral 

equilibria in hydrothermal systems: 

Reviews in economic geology, v. 1, Society 

of Economic Geologist, p. 1-43. 

Harding Lawson Associates, 1985, Geothermal 

resource assessment and exploration. Desert 

Hot Springs, Caiifomia: 65 p. 

Jennings, C.W., 1975, Fault map of Caiifomia 

with location of volcanoes, thermal springs, 

and thermal wells: Caiifomia Division of 

Mines and Geology, (Seologic Data Map no. 1. 

Lachenbruch, A.H., Sass, J.H., Galanis, S.P. 

Jr., 1985, Heat flow in southernmost 

Caiifomia and the origin of the Salton 

Trough: Journal of Geophysical Research, 

v. 90, no. B8, p. 6709-6736. 

Proctor, R., 1968, Geology of the Desert Hot 

Springs - Upper Coachella Valley area, 

Caiifomia: Caiifomia Division of Mines 

and Geology, Special Report no. 94, 50 p. 

Russell, B., 1977, A reconnaissance resource 

assessnent of the Desert Hot Springs eirea; 

Caiifomia State University at Fullerton, 

15 p.

Ceothermal Resources Council TRANSACTIONS, VOL 9 - PART I, Augusl 1985 

CHEMISTRY OF LOW-TEMPERATURE CEOTHERMAL WATERS AT KLAMATH FALLS, OREGON 

C. J. Janik', A. H. Truesdell', E. A. Saramel', and A. F. White' 

'U.S. Geological Survey, Menlo Park, California 94025 

'Lawrence Berkeley Laboratory, Berkeley, California 94702 

ABSTRACT 

Thermal water at Klaraath Falls, Oregon, occurs 

in a heterogeneous aquifer at depths of 60 to 610/ 

meters over an area of about 5 square kilometers. 

Waters raeastjring 70 to 100°C are utilized for 

district space heating. These thennal waters entdi 

the shallow aquifer through a permeable fault zone/ 

on the northeast side of the city, and undergo | 

mixing and cooling as they.flow southwestward. |/ 

Chemical and isotopic analyses of well discharges / 

indicate that in the aquifer mixing occurs becweenj 

shallow cold groundwater containing 2.0 TU tritium 

and a deeper tritium-free therraal groundwater at • / 

100 to 120°C. This deeper water apparently results| 

from the mixing of old, tritium-free cold ground-1 

water and deep thermal groundwater at about 190°C 

and 120 rag/kg Cl. The temperature and chlorinity 

of the deep thermal water are based on SO^-isotopi/l 

and silica geothermometers and chloride and silica/ 

mixing models. 

INTRODUCTION 

The city of Klaraath Falls is located east of 

the Cascade Range in south-central Oregon. This 

comraunity of about 17,000 persons utilizes a shallow 

(91 ra in depth) dips 

toward the southwest as does the general topography. 

Reported raaximum temperatures in the thermal aquifer 

are highest (95 to 120°C) near the vicinity of the 

major NW-trending fault, and decrease (to •

JANIK ct al. 

Old Fort Road valley, suggesting that artesian 

pressures and high teraperatures are transmitted 

along a permeable NE-trending fault zone that cuts 

across the main fault (Fig. 2). 

CHEMICAL COMPOSITIONS 

Analyses of Klaraath Falls therraal and non-thential 

waters frora Benson and others (1984, Ch. 4), and 

Saramel (1980) along with new analyses are given in 

Table I. Therraal waters from Klamath Falls wells 

contain (in order of decreasing concentration) 

SO4, Na, Si02, ^^' HCO3, Ca, and K with minor 

P, Li, Mg, and Al. Nonthermal well waters are 

more dilute and contain (in order of decreasing 

concentration) HCO3, Si02, Na, Ca, Mg, Cl, K, 

and SO4. Analyses of thermal and non-thermal 

Klamath Falls well waters are compared in Figure 3. 

Cold spring waters in the vicinity of Klaraath Falls 

contain less Na and Cl than non-thermal well waters 

(Table 1). Constituents of thermal waters show 

limited ranges of concentration, with raost variation 

in K, Ca, Mg and Si02 (Fig. 3).An increase in Si02, 

Na, K, and Cl concentrations is observed for samples 

Collected during the puraping tests (Table I). As 

discussed below, the variation in the cheraistry of 

the thermal waters is apparently caused by mixing 

with cooler waters of different composition and by 

equilibration with rock rainerals at different 

temperatures. 

ISOTOPIC COMPOSITIONS 

Water from Klamath Falls cold wells and springs 

is isotopically similar to rainwater but shows some 

effects of evaporation before infiltration. The 

oxygen-18 and deuterium contents of these waters 

fall along a local "meteoric water line" (MWL) 

sirailar to the global MWL (Craig, 1961), but with 

a "deuterium excess" of about •^6 rather than -^10 

(Fig. 4). The thermal waters shown in Figure 4 

are significantly lower in 6D and higher in 4'°0 

than local cold waters. Concentrations of D and 

''0 in precipitation worldwide have been observed 

to decrease with increase in elevation, latitude, 

and distance inland, and with decrease in temperature 

(Craig, 1961). Thus the lower deuterium content 

of the Klaraath Falls therraal waters compared to that 

of the cold waters, suggests that the recharge to 

the geotherraal aquifer occurs at greater elevations 

than the recharge to the cold aquifer or, much 

less probably, consists of old waters from a time of 

Colder climate (Buchardt and Fritz, 1980). The 

higher ' '0 concentrations in the therraal waters 

relative to waters on the MWL represents an "oxygen 

isotope shift" caused by long contact with ''0-rich 

rock minerals at elevated teraperatures. The isotopic 

(''0, D) variation of the thermal waters 

results frora raixing with local cold groundwater 

and frora infiltration of evaporated surface water 

(Fig. 4). 

The tritium content of a sample from the city's 

raajor cold-water supply (well 500) is very low at 

0.14 Tritium units (TU). The residence time in 

the cold aquifer is at least 30 years because this 

water can have only a very small contribution from 

high-tritium precipitation (with 30 to IOOO TU) that 

postdates nuclear bomb testing in the mid-1950s. 

The tritiura in this water may represent prebomb 

tritiura (estimated at 10 TU originally), which has 

undergone radioactive decay during 6 half lives 

326 

of 12.3 years indicating that the water is older 

than 70 years (Gat, 1980). Alternatively it could 

have orginated in a steady-state, well-mixed 

reservoir with the sarae fraction of inflow and 

outflow each year. In such a reservoir the average 

age of water with

water as indicated by relatively low teraperature and 

Cl (40 mg/kg) and high tritiura (9.5 TU) but has only 

0.02 mg/kg Mg (Table 1). In the analyses reported 

here and by Sammel (1980) of waters over 60°C only 

one has more than 0.1 mg/kg Mg. Cooler spring and 

well waters below IS'C have increasing Mg with 

decreasing temperature (2 to >12 mg/kg, of the 

reliable analyses). There are no waters between 

38 and 60°C. 

The situation with tritium is no better, with 

most thermal well waters near the limit of detection 

(about 0.1 to 0.2 TU) and sorae cold waters also 

having little tritium (e.g., well 500 with 0.14 TU). 

Although a relation can be seen between tritium and 

temperature (Fig. 5) and chloride and teraperature 

(Fig. 6), there is little trend between tritium and 

Cl. Probably two cold water sources are involved, 

one very shallow containing tritium and a deeper one 

that is tritiura free. The shallow mixing that is 

observed does not define the deep thermal end member 

and there is no indication that the highest teraperature 

reported (140°C in an unexploitable well; P.J. 

Lianau, written coiranun. , 1982) is the maxiraura 

teraperature of the system. 

GEOTHERMOMETERS AND MIXING MODELS 

Certain cheraical and isotopic reactions reequilibrate 

sufficiently slowly as fluids cool that 

evidence of higher temperature equilibria are 

preserved. These reactions may thus be used as 

geotherraoraeters and have been calibrated experimentally 

or empirically to indicate probable maximum 

temperatures attained. Calculated geotherraometer 

temperatures for Klaraath Falls thermal waters are 

given in Table 2. 

In dilute waters, cation geotherraoraeters are 

likely to be affected by re-equilibration, and at 

Klamath Falls they show teraperatures close to those 

raeasured at the sarapling point. The average teraperature 

from the Na-K-Ca geotherraometer (Fournier and 

Truesdell, 1973) is 81 ±6°C. Cation geothermometer 

teraperatures of samples taken before the pumping test 

agree closely with measured teraperatures. Saraples 

taken during pumping agree less well because waters 

chemically equilibrated at other temperatures were 

rapidly heated or cooled during passage to the wells. 

Silica concentrations are greater than expected 

for saturation with silica minerals (other than 

amorphous silica) at sarapling temperatures and 

suggest equilibration at higher teraperatures, deeper 

in the reservoir (Fig. 8). Silica in the well 

waters cannot result frora equilibrium with amorphous 

silica because the waters are undersaturated with 

this mineral. Direct use of silica geothermometers 

suggests temperatures of 100 to 150°C (Table 2) but 

silica concentrations are probably affected by 

raixing as discussed below. 

The sulfate-water isotope geothermometer depends . 

on fractionation of ''0 between SO4 and H2O, a 

process that is reasonably rapid at high temperatures 

but very slow at low temperatures (McKenzie 

and TruesdeU, 1977). At Klamath Falls, this 

geothermometer is unlikely to be influenced by 

contamination because the thermal waters have 

higher SO4 than cold waters and because no other 

sulfur-containing material (H2S, sulfates) are 

reported in the system. The temperature indicated 

by using the observed water-'°0 compositions is 

189 ±4°C for thermal waters (Table 2). 

327 

JANIK et al. 

At 189''C the half time of sulfate-water "0 

equilibration based on experimental rate studies is 

only 2.4 years, and 97 percent equilibration would 

be expected in 12.3 years (McKenzie and Truesdell, 

1977). If the maximum teraperature in the systera 

were 140''C the water would be 97 percent equilibrated 

in 55 years. Lack of equilibrium from short 

residence at any temperature below 180°C is not 

consistent with the tritium concentrations. From 

the experimental data and experience with this 

geothermometer in other geotherraal systems 

(Truesdell, 1976) we are confident that the 

waters have resided at about 180°C long enough to 

equilibrate and that they have not been at their 

present temperature (in the shallow therraal aquifer) 

more than 20 years. 

Silica mixing calculations (Truesdell and 

Fournier, 1977) based on 1983 silica data indicate 

an average temperature of 185 ±18°C (1 standard 

deviation of 14 samples with 2 outlying values 

excluded). Using only data on samples collected 

during the pumping tests, the average calculated 

teraperature is 192 ±U°C, but this temperature 

may be high because of lack of equilibrium. Silica 

concentrations previously reported from wells 

sarapled in this study produced a wider range of 

mixing-model temperatures (148 to ISO'C) and led to 

a lower estimate of reservoir temperatures (Sairanel, 

1980). Not all previous samples were properly 

treated to preserve silica and the recent analyses 

are probably more reliable. The estiraate of 185°C 

is consistent with the sulfate isotope teraperature 

of 189'"C. Mixing temperatures based on chalcedony 

saturation are about 30°C lower. These are 

considered less likely because chalcedony is 

metastable and in the presence of water should 

convert corapletely to quartz given the minimum 

tirae and temperature indicated for the Klamath 

Falls therraal aquifer. Other sources of silica 

(feldspars, etc.) would also rapidly alter in part 

to quartz and would not control silica concentrations. 

Temperatures based on chalcedony or other 

silica sources do not agree with S04-isotope 

temperatures. 

If equilibration with quartz is assuraed at a 

temperature of 185°C (Fournier and Potter, 1982), 

and if the cold and mixed waters contain 45 and 

120 mg/kg Si02 respectively, then the fraction of 

high-teraperature water in the reservoir mixture is 

calculated to be about 44 percent. Using 185°C as 

the temperature of the hot-water end member in a 

chloride-teraperature mixing model, and assuming 

the cold water to contain 10.5 mg/kg Cl at 20''C 

and the mixed water to contain 55 mg/kg Cl, on the 

basis of 1983 saraples, the chloride concentration of 

the hot -water end raember is calculated to be about 

120 mg/kg. Applying the raixing fraction (44 percent) 

and assuming no oxygen shift for the cold end 

member, we calculate that the hot-water end member 

raay have a 6' °0 value about -13.5 and a 6D 

value near -129 (Fig. 4). 

SUMMARY 

From considerations of raixing, frora 

geothermometry, and from tritiura analyses we can 

form a conceptual model of the geothermal system at 

Klamath Falls. Wells sampled appear to draw water 

from a shallow thennal aquifer at 70 to 100°C where 

hot water at 100 to 120°C with zero tritiura mixes

JANIK et al. 

with a cold water at about 20°C with 10.5 rag/kg Cl 

and 2.0 TU tritium. Different raixing ratios in the 

aquifer result in well waters of different temperatures 

and corapositions. The 100 to 120°C hot 

water may be derived by upflow from a deeper high 

teraperature zone where mixing of older, tritium-free 

cold and hot waters occurs. Although the indicated 

high-teraperature end-member water has not been 

encountered by wells drilled thus far, the 

geocheraical relations indicate teraperatures of 

150 to 190°C somewhere in the system. 

REFERENCES 

Buchardt, B., and Fritz, P., 1980, Environraental 

isotopes as environraental and cliraatological 

indicators, _iti Fritz, P., and Pontes, J.C, eds.. 

Handbook of Environraental Isotope Geocheraistry: 

Elsevier, p. 473-504. 

Benson, S.M., Janik, C.J., Long, D.C, Solbau, R.D., 

Lienau, P.J., Culver, G.C, Sararael, E.A. , 

Swanson, S.R., Hart, D.N., Yee, Andrew, White, 

A.F., Stallard, M.L., Brown, A.P. , Wheeler, M.C., 

Winnett, T.L., Fong, Grace, and Eakin, G.B., 

1984, Data from puraping and injection tests and 

cheraical sampling in the geothermal aquifer at 

Klaraath Falls, Oregon: U.S. Geological Survey 

Open-File Rep. 84-146, 101 p. 

Craig, Harmon, 1961, Isotopic variations in meteoric 

waters: Science, v. 133, p. 1702. 

Fournier, R.O., 1977, Cheraical geothermometers and 

raixing models for geothermal systems: 

Geothermics, v. 5, p. 41-50. 

Fournier, R.O., and Potter II, R.W., 1982, A revised 

and expanded silica (quartz) geotherraoraeter: 

Geotherraal Resources Council Bull., v. ll, 

no. 10, p. 3-12. 

Fournier, R.O., and Rowe, J.J., 1966, Estiraation of 

underground teraperatures from the silica content 

of water from hot springs and wet-steara wells: 

Amer. Jour, of Sci., v. 264, no. 9, p. 685-69 7. 

t>^l,«4-

' Satnp I e 

3 5 

45 

Z15 

27i 

272 

272 

304 

Earlier-^na 

OIT *6 

'.' 

A. of Cad 

Hedo-Bell 

Ff iesen 

Serruys 

'Sharp Sp 

Shell Kk Sp 

Ijuiarain^bird 

Bacfcley Sp 

tleuhert Sp 

Table I- Cheraic'aL and Laotopic aaalyaec gf water f com veils aiiH sprînga ai Klamach Falls j Oregon (Cont'iiiueci) 

Dace .T. 

8/10/83 

a/15/83 

8/15/83 

J/08/ai! 

8/09/83 

s/24/ai 

a7l7/B3 

yses ai. liot wacer 

8/24/72 

3/31/75 

8/27/76 

1/24/55 

2/19/55 

12/22/54 

6/06/74 

a/OS/72 

tmni 

imii2 

8/05/72 

82 

84" 

71 

95= 

98= 

_^c 

47 

88 

79 

87 

a I 

7 3 

;i 

IS 

U 

12 

li 

17 

Si02 Na 

lli^t. water we Lis, sampled dtiri-ftR 1983 purapitiR teacs' 

1-2 6,. 6 

120.7 

109.3 

119.8 

130.1 

120-. 7 

97.3 

wells' 

— 

90 

110 

ai 

87 

83 

Earlier ana Lyses of cold wacei I' 

Ore, Wgtcr 

Corp Well 

9/--/7i 14 ll 

43 

60J 

4 i'l" 

18 

4e

JANIK et al. 

— Pilncipal hot-w«ll Al. 

( y FoimAi in«fmat-«prfnB •.••- 

^.,_—- Araa of gumo.a •nd aft*,!*! 

walls 

• Wall 

^T"^ Traca of oflneloal lault 

Figure 1. Map of Klamath Falls, Oregon, showing 

location of hot-well area, trace of the principal 

fault, and locations (numbered as in Tables l and 2) 

of wells sarapled in 1983. 

-95 

-100 

-105 

-110 

^-115 

-120 

-125 

• 130 -, 

-135 

D Mot uolls. June 1983 

O Hot uells, 1983 le«l 

a Cold wells. Juno 1983 

V Cold waters (Sofntnol. 19801 

O Hot wells (Sammul, 19801 

-17 -16 -15 -14 

fi'Ô. pertnil 

Colcutotod 

d.*op wolef 

•J 

KlomaLh 

Laka 

-13 -12 

Figure 4. Hydrogen and oxygen isotope compositions 

of therraal and nonthermal waters, and calculated 

composition of deep reservoir water. 

330 

• Wall 

.ff Traca o* fault 

o-" Infe""c

.3 I 

D 

a 

o 

DIRECT HEAT 

APPLICATION PROGRAM 

SUmARY 

PRESENTED AT THE 

GEOTHERMAL RESOURCES COUNCIL 

ANNUAL MEETING 

SEPTEMBER, 1979 

PREPARED FOR THE 

U.S. DEPARTMENT OF ENERGY 

UNDER CONTRACT NO. DE-AC07-76 I DO!570 

EDITED AND PUBLISHED BY 

EG&G IDAHO, INC. 

P.O. BOX 1625 

IDAHO FALLS, IDAHO 83401


The project descriptions contained in this pamphlet were prepared by the 

Project Teams of each of the twenty-two direct heat application projects 

currently in progress throughout the United States. The Department of 

Energy gratefully acknowledges their assistance in providing this infor 

mation which will assist other potential users in assessing the economic 

and technical viability of the direct use of geothermal energy. Additional 

copies of this pamphlet can be obtained through the Department of Energy 

Offices listed on page 5.

TABLE OF CONTENTS 

Special Session Agenda 1 

Direct Heat Applications Projects 4 

DOE Project Offices ., 5 

Project Location Maps 6 

Project Descriptions 10 

Aquafarms International, Inc 11 

Boise 13 

Diamond Ring Ranch . 15 

El Centro 16 

Elko Heat Company 19 

Haakon School 21 

Holly Sugar 24 

Kelley Hot Springs 31 

Klamath County YMCA 34 

Klamath Falls 36 

Madison County 39 

Monroe City 41 

Navarro College 43 

Ore-Ida, Inc 45 

Pagosa Springs 47 

Reno 49 

St. Mary's Hospital 52 

Susanville 56 

T-H-S Hospital 61 

Utah Roses, Inc 63 

Utah State Prison 65 

Page 

Warm Springs State Hospital 67

Session Description: 

Agenda: 

Panelists 

SPECIAL SESSION - DOE-SPONSORED DIRECT HEAT 

APPLICATIONS PROJECTS 

September 25, 1979 

Geothermal Resources Council 1979 Annual Meeting 

This special open session on direct heat application project 

experience, sponsored by the Department of Energy, will feature 

panel discussions on geothermal: 

Space Conditioning Systems 

Applications for Agriculture/Aquaculture 

District Heating Systems 

Applications for Industry 

Panel members are individuals with a wide variety of experience, 

who are currently involved in demonstration projects in the direct 

applications field. The panelists will present brief overviews of 

their projects, and respond to questions from the audience. Experience 

in resource exploration, well drilling, design, construction 

and permitting will be emphasized. 

1 :30 - 1:50 p.m. 

1:50 - 2:00 p.m. 

2:00 - 3:00 p.m. 

Direct Heat Applications Program Overview: 

Morris Skalka, Chief, Direct Heat Applications 

Section, DOE-Washington 

Opening Remarks: Program Moderator, Bob Schultz, 

Manager, Hydrothermal Energy Commercialization, 

EG&G Idaho, Inc. 

Panel Discussion: Geothermal Space Conditioning 

Systems 

Moderator: 

Richard Berg, Project Engineer, 

Hengel, Berg & Associates 

Robert Sullivan, Project Engineer, 

Kirkham, Michael & Associates 

Gene McLeod, Project Manager, 

MERDI, Inc. 

Roland Marchand, Chief, Engineering 

Branch, Nevada Operations Office, DOE 

Project 

Haakon School, Philip, SD 

St. Mary's Hospital, Pierre, SD 

Warm Springs State Hospital, Mt

Special Session/Agenda (continued) 

Panelists 

Marshall Conover, Project Manager, 

Radian Corporation 

Brian Fitzgerald, General Director, 

Klamath County YMCA 

Jeff Burks, Research Analyst 

Utah Energy Office 

Sharon Province, Project Manager 

Westec Services, Inc. 

Panelists 

3:00 - 3:45 p.m. Panel Discussion: 

Moderator: 

Ralph Wright, Chairman of the Board, 

Utah Roses, Inc. 

Dr. Stan Howard, Principal Investigator 

South Dakota School of Mines and 

Technology 

Frank Metcalfe, President, 

Geothermal Power Corporation 

Becky Broughton, Hatchery Manager 

Aquafarms International, Inc. 

Panelists 

3:45 - 4:00 p.m. BREAK 


Moderator: 

Roger Harrison, Project Engineer, 

Terra Tek, Inc. 

Dr. Glenn Coury, Project Manager 

Coury & Associates, Inc. 

Phillip Hanson, Project Director, 

Boise Geothermal 

Project 

T-H-S Hospital, Mariin, TX and 

Navarro College, Corsicana, TX 

Klamath County, YMCA, OR 

Utah State Prison, UT 

El Centro, CA 

Geothermal Application for 

Agriculture/Aquaculture 

Hilary Sullivan, Program Coordinator, 

San Francisco Operations Office, DOE 

Project 

Utah Roses, Inc., Sandy, UT 

Diamond Ring Ranch, SD 

Kelley Hot Springs, CA 

Aquafarms International, Inc, 

Mecca, CA 

Geothermal District Heating 

Systems 

Eric Peterson, Program Manager, 

Division of Geothermal Resource 

Management, DOE-Washington 

Project 

Monroe City, UT 

Pagosa Springs, CO 

Boise, ID

Special Session/Agenda (continued) 

Panelists 

Harrold Derrah, Assistant City 

Manager, Klamath Falls, OR 

Phillip Edwardes, Principal Investigator 

Susanville, CA 

David Atkinson, President, 

Hydrothermal Energy Corporation 

Panelists 


Moderator: 

Dr. Jay Kunze, Vice President & 

General Manager, Energy Services, Inc. 

Robert Rolf, Director Technical 

Services, Ore-Ida, Inc. 

Sheldon Gordon, Project Engineer, 

Chilton Engineering 

Lee Leventhal, Project Engineer, 

TRW, Inc. 

Project 

Klamath Falls, OR 

Susanville, CA 

Reno, NV 

Geothermal Applications for 

Industry 

Robert Chappell, Project Manager 

Idaho Operations Office, DOE 

Project 

Madison County, ID 

Ore-Ida, Inc., Ontario, OR 

Elko Heat Company, Elko, NV 

Holly Sugar, Brawley, CA

DIRECT HEAT APPLICATION PROJECTS 

The use of geothermal energy for direct heat purposes by the private. •:• 

sector within the United States has been quite limited to date, yet -- •, • 

there is a large potential market for thermal energy in such areas as 

industrial processing, agribusiness, and space/water heating of commercial 

and residential buildings. Technical and economic information is 

needed to assist in identifying prospective direct heat users and to 

match their energy needs to specific geothermal reservoirs. Technologi-i 

cal uncertainties and associated economic risks can influence the user's 

perception of profitability to the point of limiting private Investment 

in geothermal direct heat applications. 

To stimulate development in the direct heat area, the Department of Energy, 

Division of Geothermal Energy, issued two Program Opportunity Notices. 

These solicitations are part of DOE's national geothermal energy program 

plan, which has as its goal the near-term commercialization by the private 

sector of hydrothermal resources. Encouragement is being given to the 

private sector by DOE cost sharing a portion of the front-end financial 

risk in a limited number of demonstration projects. 

The twenty-two projects summarized in this pamphlet are a direct result 

of the Program Opportunity Notice solicitations. These projects will 

(1) provide visible evidence of the profitability of various direct heat 

applications in a number of geographical regions; (2) obtain technical, 

economic, institutional, and environmental data under field operating 

conditions that will facilitate decisions on the utilization of geothermal 

energy by prospective developers and users; and (3) demonstrate a variety 

of types of applications.

DOE PROJECT OFFICES 

Three Department of Energy Operations Offices are responsible for the 

management of the direct heat application projects. The offices and 

their respective projects are: 

Idaho Operations Office 

550 Second Street 

Idaho Falls, Idaho 83401 

Contact: Robert Chappell 

Project Manager, 

(208) 526-0085 

Technical Support: 

DOE 

EG&G Idaho, Inc. 

Idaho Falls, Idaho 83401 

Nevada Operations Office 

P.O. Box 42100 

Las Vegas, Nevada 89114 

Contact: Roland Marchand 

Chief Engineering Branch, DOE 

(702) 734-3424 

San Francisco Operations Office 

1333 Broadway 

Oakland, California 94612 

Contact: Hilary Sullivan 

Program Coordinator, DOE 

(415) 273-7943 

Technical Support: 

Energy Technology Engineering Center 

Canoga Park, California 91305 

Projects 

Boise 

Diamond Ring Ranch 

Elko Heat Company 

Haakon School 

Madison County 

Monroe City 

Ore-Ida, Inc. 

Pagosa Springs 

St. Mary's Hospital 

Utah Roses, Inc. 

Utah State Prison 

Warm Springs State Hospital 

Navarro College 

T-H-S Hospital 

Aquafarms International Inc. 

El Centro 

Holly Sugar 

Kelley Hot Springs 

Klamath County YMCA 

Klamath Falls 

Reno 

Susanville

Institutional Heating Systems 

1 Navarro College & Hospital Corsicana, Texas 

Warm Springs Hospital, Montana 

Utah State Prison, Utah 

THS Hospital, Mariin, Texas 

St. Mary's Hospital, Pierre, South Dakota 

Philip School, South Dakota 

Klamath Falls, Oregon, YMCA 

INEL-S-17 788

Industrial Process Sites 

1 ORE-IDA — Ontario, Oregon 

2 Madison County ~ Rexburg, Idaho 

3 Holly Sugar ~ Brawley, California 

INEL-S-17 787

00 

t 

Agribusiness 

1 Utah Roses — Sandy, Utah 

2 Diamond Ring Ranch — South Dakota 

3 Aquafarms International — Mecca, Calif. 

4 Kelly Hot Springs -- Novato, California 

INEL-S-17 786

District Heating Systems 

1 Monroe City, Utah 

Klamath Falls, Oregon 

Boise, Idaho 

Elko, Nevada 

Madison County, Idaho 

Reno, Nevada 

Pagosa Springs, Colorado 

8 Susanville, California 

9 El Centro, California 

INEL-S-17 789

DIRECT HEAT 

APPLICATIONS PROJECT 

DESCRIPTIONS

Project Title: Commercial Culture of Macrobrachium Rosenbergii 

on Geothermal Water 

Location: Mecca, California 

Principal Investigator: Dr. Dov Grajcer, President, 

Project Team: 

- Aquafarms International, Inc. 

Aquafarms International, Inc. 

Project Objective: 

To develop a commercial-scale prawn farm in the Coachella Valley, 

utilizing geothermal water as the source of constant-temperature fluid. 

This would permit economical, year-round prawn farming. 

Resource Data: 

The project is located on 246 acres of desert land in one of the most 

desolate parts of the Salton Trough, the area between the Coachella 

Canal and the Salton Sea. 

Subsequent drilling has proven successful. Three wells have been drilled 

to a depth of about 100 ft. They are all prolific producers of warm 

water under thermo-artesian pressure. The estimated artesian head is 

about 5 psig. The total flow rate is of the order of 300 gallons per 

minute per well, without pumping. The quality of the water is superb: 

the salinity of the water is less than 600 ppm TDS, making it less 

saline than the Coachella canal water flowing by. The salinity of the 

latter is on the order of 800 to 1,000 ppm TDS. The water issues out 

of the 10-inch (O.D.) wells, at a temperature range of 84 to 87°F, which 

is ideal for shrimp farming. Detailed chemical tests of water chemistry 

have established that the water is of an acceptable quality for giant 

shrimp (or prawn) farming. 

System Design Features: 

The equivalent energy demand for raising shrimp or prawn in artificially 

heated ponds is on the order of 170 billion Btu per year for 

Coachella Valley groundwater and ambient air conditions for a 50-acre 

pond farm. The equivalent energy saving would amount to about $560,000 

per year (at $2/MMBtu and 60% boiler efficiency). 

The three geothermal wells on the property provide water at the required 

pond temperatures, Geotechnical investigations will determine if 

slightly higher water temperatures would be expected at a slightly 

greater depth. In case of discovery of hotter water, it would be possible 

to control pond temperature in winter with greater ease, by proper mixing 

of water from wells of different temperatures. 

It is estimated that well pumping would require a 10-kW generator to 

be installed on the deep well. 

11

Commercial Prawn Farm Project Page 2 

Project Description: 

Status: 

Aquafarms International, Inc. (All), a small California corporation, 

is developing a 50 acre prawn farm on its property in the Dos Palmas 

area, east shore of the Salton Sea, utilizing geothermally heated water. 

Extensive genetic and field work have already been completed by All 

to achieve adaptation of the giant Malaysian prawn, Macrobrachium 

rosenbergii, to local water, soil, and climate conditions. 

The giant Malaysian shrimp enjoys many advantages over many other 

crustaceans. It adapts to a relatively wide temperature range, with 

the optimum temperature being in the 80 to 85°F range. The female 

prawn is highly productive and protects her eggs, resulting in a relatively 

high (30 to 50%) survival rate of the larvae. The larvae metamorphose 

to juvenile prawns in 22 to 35 days; depending upon temperature, 

the juveniles reach maturity in 7 to 8 months. And, finally, the 

meat has excellent taste and quality, and the product is much in demand 

worldwide. 

The project will utilize geothermal water issuing from three existing 

shallow wells, plus one deeper well to be drilled as part of the project, 

to provide enough warm water for continuous, year-round, prawn farming 

operation. Appropriate geotechnical studies will be carried out to 

determine optimal location for the new well, to test hydrologic characteristics 

of all wells, and to determine best methods of disposal of 

the water after it has been used in the prawn ponds. Studies of optimum 

feed, flow-through, efficient water quality control methods, and harvesting 

methods will also be determined. 

The environmental report has been submitted for approval. 

12

Project Title: Boise City - A Field Experiment in Space Heating 

Location: Boise, Idaho 

Principal Investigator: Phil Hanson, Director, Boise Geothermal (i208) 384-4013 

Project Team: 

- Boise City 

- Boise Warm Springs Water District 

- CH2M Hill Engineers 

Project Objective: To develop a geothermal space heating system to serve 

the largest possible market in and around the Boise central business 

district. 

Resource Oata: The resource area is commonly referred to as the Boise Front. 

This area appears to be fault controlled, with the source of water 

being the annual runoff in the mountains immediately behind Boise City. 

There is a long history of using this resource data, dating to 1892 

when the first wells were drilled to a depth of 400 feet. These wells 

are still productive, with water temperatures relatively invariant at 

170°F. Since that date, there has been fairly continuous development 

of hot water wells. Records available on some 70 wells show temperature 

ranges of 75 to 170°F, and depths ranging up to 1,200-f feet. 

Production varies over the range up to 800 gpm. 

System Design Features: Boise Geothermal is a joint venture of Boise City 

and Boise Warm Springs Water District. This joint venture will develop 

a space heating system consisting of two major parts. The first part 

is based on the Warm Springs heating district, which, in one form or 

another, has been operating since the 1890's. This part of the system 

presently serves about 220 residences, based on two 400-ft wells with 

temperatures of 170°F. This part of the system will be improved to 

provide expanded service to the residential community. 

The second part of the system will draw on a separate part of the 

resource area to supply heat to the central business district. It is 

planned that the system will serve, initially, approximately 11 major 

buildings. These buildings range from the 270,000 square foot Idaho 

First National Plaza, built in 1978, to a renovated 1930's hotel 

that is now an office building. 

The types of heat exchangers used will vary. The system capacity is 

a nominal 5,000 gpm, designed to take advantage of a 40 to 50°F temperature 

drop (170 to 120°F) to heat residential and commercial buildings. 

Fuel savings are expected of 230,000 barrels of oil for a system serving 

500 to 1,000 residences and 11 office buildings. 

13

Boise City Project Page 2 

Project Description: The project is managed and operated through Boise 

Geothermal. A Board of Directors, made up of the Boise City Council 

and members of the Boise Warm Springs Water District Board, provides 

policy direction to Boise Geothermal. An Executive Committee maintains 

daily involvement in project work. Overall project management 

is the responsibility of a Project Director, who reports to the 

Project Board. CH2M Hill provides project technical direction. 

Funding for the project is being supplied by the Economic Development 

Administration, the Department of Energy, Boise City, and Boise Warm 

Springs Water District. As the project develops, funding is planned 

from other sources. These funds will be used to prove the extent of 

the resource. If the resource is large enough, the first segment of 

the system will serve 500 residences and 11 office buildings. Service 

to this segment will be evaluated, to determine the technical and 

economic feasibility of expanding the system. 

Status: Contracts with EDA and DOE were signed in July 1979. Preliminary 

work on geological and environmental studies actually began in March 

1979. An environmental report has been completed. Geology studies 

are continuing, with some concurrent drilling. All wells should have 

been drilled and service begun between 1980 and 1982. 

14

Project Title: Diamond Ring Ranch Geothermal Demonstration 

Heating Project 

Location: Mid-central South Dakota, 35 miles west of the 

state capitol 

Principal Investigator: Dr. S. M. Howard, Professor of Metallurgical 

Project Team: 

Engineering, (605) 394-2341 

- South Dakota School of Mines and Technology 

- Re/Spec, Inc. 

- Diamond Ring Ranch 


Utilize existing Madison well to provide grain drying, cattle warming, 

and space heating for homes. 


The geothermal water is coming from the Madison Limestone, which is 

under most of western South Dakota, at depths from 2,500 to 7,500 

feet and temperatures from 100 to 195°F. The Madison is a major 

aquifer of South Dakota, yielding good quality drinking water. The 

existing well is 4,100 feet deep, flowing at approximately 152°F 

and 180 gpm. 


Status: 

The system is designed using PVC piping and plate-type isolation 

heat exchangers made of 316 stainless steel. The system is designed 

for a 20°F temperature drop across the isolation exchangers. The 

grain dryer was designed to use antifreeze in its "clean" water side, 

to avoid complications associated with freezing weather. The space 

heating provided to the homes will use existing duct work and installation 

of water-to-air exchangers in line with the existing heating 

system. This will permit the existing system to function as a backup 

unit, if necessary. 

The systan is designed for simplicity and minimal control systems, 

to permit economical installation and elementary operational problems. 

Ground breaking ceremonies were conducted on July 19, 1979, with 

project completion slated for October 19, 1979. The main pipeline 

has been excavated and is nearly installed. The grain dryer is on-site 

and retrofit procedures are commencing. The retrofit for the space 

heating Is also underway. The project will hopefully be completed 

to permit some grain drying operations to begin In late September. 

15

Project Title: City of El Centro Geothermal Energy, Utility 

Core Field Experiment 

Location: El Centro, California 

Principal Investigator: Mr. G. L. Herz, Assistant City Manager of El Centro 

Project Team: 

(714) 352-9440 

- City of El Centro 

- WESTEC Services, Incorporated 

- Chevron Resources Company 


The overall objective of this field experiment is to demonstrate the 

engineering and economic feasibility of the utilization of moderatetemperature 

geothennal heat, on a pilot scale, in the City of El Centro, 

for space cooling, space heating and domestic hot water. This field 

experiment will provide visible evidence of the profitability of 

direct heat applications to residential/commercial space conditioning, 

particularly in the southwestern United States. 


The geothermal reservoir which is the energy source for this demonstration 

is embodied in a 13.5 square mile area known as the Heber 

Known Geothermal Resource Area in the Imperial Valley. The City of 

El Centro is 4-1/2 miles north of the center of the KGRA, in an area 

where well temperature gradients should be 2 to 4°F per 100 feet in 

depth. 

Reservoir Characteristics (predicted) 

at the El Centro City Site 

Total Dissolved Solids (TDS) 14,000 ppm 

Brine Chemistry for Thermodynamic 14,000 ppm solution of NaCl 

Calculations 

pH 6.2 

CO2 by weight of flashed steam _< 0.3% 

Methane and hydrogen sulfide by trace 

weight of flashed steam 

Maximum supply rate per well 365,000 Ib/hr per well 

Downhole Brine Condition at the Saturated 250°F at 8,500 feet 

City 

Brine return temperature at the >_ 160°F 

reinjection well 

1.6

City of El Centro Project Page 2 


The basic concept is to use the geothermal brine to heat clean City 

supply water and circulate this clean water to the Community Center 

for space and water heating purposes. Also, this clean, hot City 

supply water would be used in a lithium bromide/water absorption 

chiller to produce chilled water, which would be circulated to the 

Community Center for space cooling purposes. This design is based 

on the concept that the hot water/chilled water plant will be located 

at the proposed drill site, about 1/2 mile away from the Community 

Center. The reason this plant is not located at the Community Center 

is that the modular concept of district heating and cooling developed 

in the initial feasibility study will be evaluated in this demonstrati_. 

on. 

Under this concept, the area of a city to benefit from district heating 

and cooling would be divided into small districts in which one modular 

plant would serve a particular district. This demonstration plant 

is conceived as a modular plant serving not only the Community Center 

but, hopefully in the future, other consumers in the area--residentia1 

and industrial alike. 

Number of Production Wells 

Number of Injection Wells 

Type Absorption Chiller 

Cooling Capacity 

Hot Water Temperature IN 

Hot Water Temperature OUT 

Type Heat Exchanger 

Capacity (max.) 

Brine Temperature IN 

Brine Temperature OUT 

Hot Water Temperature IN 

Hot Water Temperature OUT 

Estimated Geothermal Fuel Cost/ 

Million Btu 

Annual Fuel Savings 


Key Design Features 

One 

One 

Lithium bromide/Water 

101 tons nominal 

65 ton IS available 

235°F 

215°F 

Undete irmined at this time 

1.2 X 10^ Btu/hr 

250°F 

> 160*= 'F 

215°F cooling mode 

175°F heating mode 

235°F cooling mode 

195°F heating mode 

$4.78 (based on fully developed 

district wide system, including 

industrial park use) 

4.6 X 10^ cu ft/yr natural gas 

1.7 X 10^ kWh/yr electricity 

The project plan calls for drilling a geothermal well within the city, 

building a pilot hot water/chilled water plant at the wellsite, and 

distributing the hot or chilled water to the El Centro Community Center 

(located about one-half mile away from the pilot plant). Heat from 

the brine will be transferred to the working fluid by way of heat 

exchangers located at the wellsite. City supply water has been selected 

as the working fluid because of its relatively low cost and availability. 

17

City of El Centro Project Page 3 

Status: 

The heated city water will be used in the winter to supply space heat 

and heat for domestic water for the Community Center. During the 

summer, the heated city water will be used in a lithium bromide/water 

absorption process to produce chilled water to be used for space 

cooling the Community Center. The Community Center will be retrofit 

with heating/cooling colls for the space conditioning requirements. 

The prime contract for this project between the Department of Energy 

(DOE) and the City of El Centro was executed on July 11, 1979. The 

environmental impact report was certified by the El Centro City Council 

on July 5, 1979. The technical conceptual design was completed on 

August 3, 1979, and the detailed design phase is now in progress. 

18

Project Title: Field Experiments for Direct Uses of Geothermal 

Energy: Elko Heat Company, Elko, Nevada 

Location: City of Elko, Nevada 

Principal Investigator: Mr. Ira S. Rackley, P.E., Project Manager 

Elko Heat Company, (702) 738-3108 

Project Team: 

- Elko Heat Company, Elko Nevada; Mr. Jim Weeks, President 

- Chilton Engineering, Elko, Nevada; Mr. Ira S. Rackley, P.E., 

Project Manager, and Mr. Sheldon S. Gordon, P.E., Project 

Engineer 

Project Objectives: 

This project was selected to demonstrate the technical and economic 

feasibility of the direct use of geothermal brines from the Elko 

KGRA for the purpose of providing space, water, and process heat. 

In a more general sense, it is the aim of the project to develop 

information and approaches that will enable the proposers to develop 

the Elko resource as a viable alternative to the consumption of 

primary fuels for space, water, and process heating in Elko. 

Objectives related to this overall goal are: 

Resource Data 

- Develop adequate resource information to allow for the design 

of the geothermal process system. 

- Use this resource information to generate a plan for the 

continued development and use of this resource after the 

period of government support. 

- Displace a significant portion of the primary fuel consumption 

in Elko for identified energy markets with geothermal 

energy. 

Resource Area: Adjacent to the Elko KGRA, within the city limits 

of Elko. 

Controlling Geologic Features: Fault zone trending north-northeast 

through city of Elko; hot water from depth ascending along the 

fracture zone. 

Predicted Temperature: Geothermometry-based predictions (240-670°F) 

(actual unknown). 

Predicted Flows: Unknown 

Depth of Resource: 700 to 2,000 feet, based on cold water well drilling 

logs (actual unknown). 

19

Elko Heat Company Project Page 2 


Production/Injection Wells: One production well (700-2,000 feet in 

depth), one injection well (similar depth). (Actual use is dependent 

on water quality considerations.) 

Heat Exchangers: Use is dependent on water quality and resource 

temperature considerations. Design at present allows for wellhead 

heat exchanger and closed-loop system circulation. Heat exchanger 

design anticipates 10-15°F approach. 

System Capacity: Present extraction permits under assumed operating 

AT of 10°F on shell side of heat exchanger provide a net capacity of 

6.74 X 10^ Btu/hr (actual capacity unknown). 

Unique Design Considerations: 

- shallow resource 

- clean resource (dilute samples at 550 ppm - TDS) 

- variety of applications: 

- commercial laundry 

- 400-unit motor hotel 

- office building 


Status: 

The Elko project involves the location and drilling of a production 

well for the purpose of extracting hydrothermal fluids from the Elko 

KGRA. These fluids are to be used to displace primary fuel consumption 

for the operation of a commercial laundry, a motor hotel, and 

an office building. 

The Vogue Laundry and Dry Cleaners requires energy for the operation of 

washing equipment, dryers, and ironers. The Stockmens Motor Hotel 

requires energy for domestic water, space, and swimming pool heating. 

The Stockmens Motor Hotel also has substantial cooling requirements 

that may be met if the geothermal source is of sufficient temperature. 

The Henderson Bank Building requires energy primarily for space heating, 

with a small domestic hot water requirement. Thus, several different 

applications of the direct utilization of the Elko geothermal resource 

will be demonstrated and tested in this program. 

The Elko project is in the resource assessment phase, with Geothermal 

Surveys, Inc. just completing the temperature probe survey, geologic 

reconnaissance, electrical resistivity soundings, sling ram soundings, 

and some of the geochemical sampling of city wells and the Elko Hot 

Springs. 

The Environmental Report has been completed for this project, with 

no significant environmental effects expected to be caused. 

20

Project Title: Direct Utilization of Geothermal Energy for 

Philip Schools 

Location: Philip, South Dakota 

Principal Investigator: Charles A. Maxon, Superintendent of Schools, 

(605) 859-2679 

Project Team: 

- Haakon School District 27-1 

- Hengel, Berg & Associates, Rapid City, South Dakota 

- Francis-Meador-Gellhaus Inc., Rapid City, South Dakota 

Project Objective: To obtain water at 155°F (66°C) from the Madison 

Formation that can be used for space heating and domestic water 

heating at the Philip School buildings of the Haakon School District 

27-1. 

Resource Data: The Madison Formation underlies most of western South 

Dakota. In the Philip area, the depth to the Madison Formation is 

approximately 4,000 feet. The temperature of the water from the 

Madison Formation in this area is 155°F (66°C). The flow rate of the 

well drilled by the school to a depth of 4,266 feet is 300 gallons 

per minute, at a temperature of 155°F (65°C). 

System Design Features: A 4,266-foot well, with artesian flow, has been 

drilled. Two stainless steel plate-type heat exchangers will be provided. 

One will provide 1,800,000 Btu/hr for space heating of an 

Armory-High School building. The other will provide 1,130,000 Btu/hr 

for space heating of an elementary school building, a vocational education 

building, and two small music buildings. Temperature of geothermal 

water delivered to heat exchangers is 155°F (65°C). Leaving 

temperature from space heating heat exchanger is not less than 130°F 

(54°C). Water leaving the space heating heat exchanger is piped 

through a domestic water heat exchanger. 

The heat energy remaining after the school space heating is satisfied 

will be piped through part of the Philip business district. The 

heating district plans to utilize the low-temperature water (approximately 

125 to 130°F) in a direct heat application, i.e., fan-coil 

type heat exchangers. 

The estimated annual fuel savings for the school is 36,200 gallons 

of fuel oil and 107,000 kWh of electricity. 

Additional savings of fuel oil will be realized from the heating 

district. 

21

Philip School Project . Page 2 

Project Description: A 4,265-foot well was drilled to the Madison Formation. 

The well will produce a sustained flow of 300 gpm of water, 

at 155°F (66°C). However, to utilize the well pressure to circulate 

the water through the heat exchangers, the heating system was designed 

to use 250 gallons per minute. 

The water will be piped from the well that is located,near the school 

buildings, to the Armory-High School building and to the elementary 

school building. 

Because of the corrosive action of the Madison Formation water, the 

recommended materials to be used in this system are 316 stainless 

steel and the plastics. 

The pipe from the well house to the buildings will be high-density 

polyethylene pipe equal to Driscopipe. Supply piping inside the 

buildings will be chlorinated polyvinyl chloride. 

A 316 stainless steel plate-type heat exchanger will be provided in 

each of the buildings. The existing low pressure steam heating system 

will be modified to hot water systems by replacing steam coils with 

hot water coils in the fan coil units, by adding additional fan coil 

units, and by using the existing baseboard radiation. One of the 

boilers will be replaced because of its condition and the other boiler 

will be retrimmed to a hot water boiler. 

The Armory-High School building is approximately 30,000 square feet. 

The heat exchanger in the elementary shool building will be used to 

heat that building, the Vocational Education building, and two small 

buildings used for music classrooms. These four buildings have approximately 

28,000 square feet. 

In addition to the space heating, the domestic hot water will be provided 

for the Armory-High School building and the elementary school 

building. A 316 stainless steel plate-type heat exchanger will be 

located next to the space heating heat exchangers. These heat exchangers 

will use either the leaving water from the space heating heat 

exchangers or the geothermal water, depending upon the space heating 

demands. 

The exit temperature from the heat exchangers will be approximately 

130°F (54°C). The water will be piped through a part of the Philip 

business district. Several building owners have indicated an interest 

in utilizing the remaining heat energy. They propose to use fan coil 

type heating-units. These units are estimated to have a life of ten 

years before they may have to be replaced. 

Because of the presence of Radium 226 in excess of the EPA allowable 

for domestic water, the water will be treated with barium chloride. 

After removal of the Radium 226, the water will be discharged into the 

Bad River, which flows through Philip. 

22 

r 

/

Philip School Project Page 3 

Status: 

The proposed barium chloride treatment plant will have two 5,000-gallon 

mixing tanks that will have a 10 percent aqueous solution. The solution 

will be added to the water. The water will pass through a static mixer. 

From the static mixer, the water will be piped to two detention ponds. 

After three days, the water will be acceptable for discharge. 

The well has been drilled, cased, and flow tested. 

The design of the retrofit is approximately 85 percent complete. A 

design review was recently completed, with some changes In the plans. 

A feasibility study, financed by nine businessmen, to use the leaving 

water from the school to heat their buildings, has been completed. 

Their final decision has been delayed because the location of the 

final discharge point has not been established. 

The most economical method of removing the Radium 226 from the water 

appears to be the addition of barium chloride and the precipitation 

of the Radium 226. 

Various locations for the treatment plant are being investigated. ' 

Bids for the heat exchangers have been received by the school. A 

final decision on the award of the contract will be made in the near 

future. 

The plans and specifications will be completed and construction contracts 

obtained, with construction starting April 1, 1980. 

23

Project Title: Geothermal Energy for Sugar Beet Processing 

Location: Brawley, California 

Principal Investigator: J. J. Seidman, F'rogram Manager, (213) 536-1955 

J. M. Kennedy, Co-Investigator, Project Manager 

Geothermal Resource, (213) 535-1571 

E. L. Leventhal, Co-Investigator, Project Manager 

System Design, (213) 536-1955 

Project Team: 

- TRW Energy Systems Group 

- Holly Sugar Corporation 


The objective of this project is to implement a three-phase program 

to replace large quantities of fossil fuels with geothermal energy 

for sugar processing at Brawley, California, in a technical straightforward, 

economically sound and environmentally acceptable manner. 


The Imperial Valley of southern California is within a major rift zone. 

Tectonic stresses, acting on valley fill sediments, have caused faulting 

and opened fracture, permitting the formation of geothermal convective 

cells. Such a convective cell is thought to exist near the termination 

of the Imperial Fault, in section 30 TUS, RUE SBBM. The local fault 

system was first mapped on the surface and later verified by geophysical 

surveys (seismic, resistivity, and heat flow) performed as part of 

this project. The fault system, which consists of four tension faults 

splaying off the Imperial Fault, is thought to provide permeability 

and the conduit for the convective cell. The geologic structure, in 

concert with the thermocline of other wells in the region, suggests 

a source of 350°F (177°C) at about 8,000 feet (2440 m). If the geothermal 

system is as predicted, a flow of about 1,000 gallons per 

minute (63 liters/sec) may be achieved. 


The system will replace one boiler that is presently used to supply 

low pressure steam (= 25 psig) to the evaporators and juice heaters, 

and will supply heat to pulp dryers. There will be about 13 heat 

exchangers in the system. Three of these will be used to generate 

25 psig steam, and the other 10 to preheat and heat the pulp-drying 

air. The capacity of the system will be 75 million Btu/hr for the 

steam generator and 160 million Btu/hr for the air heaters, for a 

total of about 235 million Btu/hr. This system will be used for about 

four months per year during the sugar campaign. 

24

Sugar Beet Processing Project Page 2 

The total cost of the system, including the study phase and the design, 

is expected to be about $20 million. It is estimated that the heat 

supplied by the geothermal resource for the 4-month campaign will save 

about 100,000 barrels of oil/year. At an estimated cost of $5-6/MBtu, 

this is equivalent to $30/barre1 of oil. Based on a full year's usage, 

the system could replace 300,000 barrels of oil and drop the cost to 

about $2/MBtu; this is equivalent to $10-15/barre1. 


Status: 

During the present phase of the contract (Phase I), the main users of 

geothermal heat in sugar processing have been investigated, an environmental 

report published, a drilling plan completed, and an application 

for a drilling permit submitted. An assumption was made that the well 

will produce water at 350°F, and, based on this assumption, low 

pressure steam generators and pulp dryers have undergone preliminary 

design. The accompanying equipment, piping, and required Installation 

have also been identified. In Phase II, one production and one reinjection 

well will be drilled, and a pilot plant will be assembled. 

The equipment design will be based on data obtained during the drilling 

of the first production well. 

The drilling of the first production well is scheduled to start in 

October 1979. 

25

INJ 

EAST - WEST DIAGRAMMATIC CROSS SECTION OF IMPERIAL VALLEY 

SEDIMENTARY COLUMN, SECTIONS 29 AND 30 T14S, R14E 

WEST EAST 

'•'••'.'î'-'.'S'.'i 

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FAULT, APPROXIMATE WHERE DASHED 

LITHOLOGY BOUNDARY 

IN-OUT INDICATES DIRECTION OF HORIZONTAL MOVEMENT 

IAL FAULT 

COLORADO 

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SEDIMENTS 

IMPERIAL 

FORMATION

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With Geothermal Retrofit Equipment Areas 

FIGURE NO. 

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±11 

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Figure 5. Geothermal Sugaf Project Schematic 

¥ 

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GEOTHERHAL SOtLCR 

OONOENIATE RCTVRN

Project Title: Kelley Hot Springs Agricultural Center 

Location: Kelley Hot Springs, Modoc County, California 

Principal Investigator: Alfred B. Longyear, (916) 441-4510 

Project Team: 

- Geothermal Power Corp., Prime Contractor; Frank Metcalfe, Program 

Manager 

- Agricultural Growth Industries, Inc.; Dr. Richard Matherson, 

Agricultural 

- International Engineering Co.; Leonard A. Fisher, Civil Engineering 

- Coopers & Lybrand; William R. Brink, Economics and Project Cost 

Management 

- Ecoview; Dr. James Neilson, Environmental Report 

- Carson Development Co.; Johan Otto, Construction Management 

Project Objective: To demonstrate the economics and feasibility of using 

low-temperature geothermal energy for an Integrated swine raising 

complex in Northern California. 

i^îuii IO pull. WI UII*- iiwuw^' iiuucuu piuviii^c:. illc riu i\ivc:i vail cjf 

contains a thin veneer of stream-channel alluvium, flanked by terrace 

deposits and older and younger fan deposits. Beneath this are sedimentary 

and tuffacious beds of the Alturas Formation. Overlying these 

on higher hills are basalt flows of Pliocene and Pleistocene age. 

The principal fault of the region .is the northwest-trending Likely 

fault, which passes about one mile west of Kelley Hot Springs, and 

which appears to be a significant regional boundary. 

Extensive exploration data include: Reconnaissance-level geologic 

mapping and gravity surveys, an aeromagnetic survey, at least 30 sq mi 

of electrical resistivity surveys, a reconnaissance-type telluric 

survey, a ground-noise and micro-earthquake survey, geochemical analyses, 

extensive temperature gradient surveys over a 15 sq mi area with 

2.5-3 HFU across the area and a high of 20 HFU in certain holes. 

Two exploration wells have been drilled. In 1969, Geothermal Resources 

International drilled to 3,200 feet, 1/4 mile south of the spring with 

a maximum temperature of 110°C (230°F) at bottom. In 1974, Geothermal 

Power Corporation drilled to 3,396 feet, approximately 1-1/2 miles due 

east of the GRI #1 well. The maximum bottom hole temperature of 115°C 

(239''F) was measured in 1977 in KHS #1. The lithology of the two 

wells is similar. 

The proven reserve in this project is a body of hot water at over 240°F 

in a porous reservoir between about 1,600 to 3,400 feet depth, covering 

an area of several square miles. A conservative estimate of the resource. 

31

Kelley Hot Springs Agricultural Center Page 2 

assuming an areal extent of 4 sq mi, thickness of 2,000 ft, a reservoir 

temperature of 240°F, a reinjection temperature of 80°F, and a porosity 

of 20% (KHS i^ logs), will amount to heat in the fluid of 6.73 x lol^ 

calories. The reservoir within the drilled depth has sufficient reserve 

to supply the proposed plant, plus considerable additional development. 

System Design Features: The GRI #1 well will be reentered and pump tested. 

An additional standby and reinjection well are planned. A primary 

tube and shell heat exchanger will be used. The geothermal fluid will 

be maintained in the fluid state from supply to reinjection. Fan coils, 

radiant floor and possible plate-type wall heaters will be the principal 

sources of space heating. Absorption refrigeration for sprouted grain 

raising and liquid cooling in the feed processes will be evaluated. 

Heating coils in the methane digesters and in the treatment ponds will 

also be evaluated. The system will operate with 240°F nominal supply 

and reinjection at 80°F. The peak capacity is on the order of 54 million 

Btu/hr. The annual fuel savings is estimated to be 2.5 million gallons 

of oil. 

Project Description: Based upon the characteristics of the Kelley Hot Springs 

resource, regional markets and raw material supplies, and a recent 

related DOE PRDA^, a totally confined swine raising complex was proposed 

for a field experiment. 

1 

A 1,200 sow swine raising complex, utilizing geothermal direct energy, 

will be designed, developed, constructed, and operated as a field ' 

experiment. During subsequent operations, it is planned that the complex 

will be expanded to 4,800 sow capacity. The field experiment will be 

composed of a feed production facility, a totally confined system of 

swine raising buildings, employee services and maintenance facility, 

and a waste management system. 

All commercial hardware will be utilized. Commercial swine raising 

facilities will be evaluated. Engineering design effort will be directed 

to adapt the commercial hardware and systems to geothermal applications. 

Engineering and economic trade studies will be conducted to determine 

benefit/costs and optimum design. Some of the important options are: 

- A reinjection well vs. a reinjection pipeline to KHS #1 well. 

- Geothermal hydroponic-sprouted grain raising as a feed constituent 

vs. purchase of barley sprouts from malting processes 

vs. no sprout content in the feed. 

- Geothermal absorption refrigeration for various cooling loads, 

i.e., sprout raising, sprout processing, space cooling. 

- Geothermal wall heaters vs. added insulation, and similar 

evaluations for all other space heat loads. 

- Geothermal methane generation vs. protein extraction vs. 

conventional commercial sewage treatment facilities. 

Mountain Home Geothermal Project, DOE Contract DE-AC07-78ET28442, 

1978. 

32

Kelley Hot Springs Agricultural Center Page 3 

Final design will be based upon economic analysis, including consideration 

of geothermal and other tax incentives and their impact on 

the rate of return to the investors. Emphasis will be placed upon 

simplicity and a straightforward commercial approach. 

Status: The project was entering contract negotiation at the time of this 

writing. 

33

Project Title: Klamath Falls YMCA 1-78 

Geothermal Space/Water Heating 

Location: Klamath County YMCA 

Klamath Falls, Oregon 

Principal Investigator: Brian C. FitzGerald, General Director, YMCA 

Project Team: 

- Klamath County YMCA Board of Directors 

- E. E. Storey & Son Well Drilling 

- Balhizer & Colvin, Engineers 

- Alan Lee, Attorney at Law 

- O.I.T., Geo-Heat Research Consultants 

- Honeywell Control Systems 


To demonstrate the viability of geothermal energy used in a nonprofit 

social service corporation. The project is a direct use 

retrofit for space and water heating. 


The YMCA is located over the Klamath KGRA, with a present well drilled 

to 2,016 feet. The production capacity is in excess of 500 gpm, at 

110°F. The well is cased to 512 feet, leaving exposed 325 feet of 

shale material. Consequently, it is felt that considerable cold surface 

water is mixing with hotter water found at lower levels, which 

include 850, 950, 1,150, and 1,345 feet. Static water temperature 

at 1,350 is Ue'F. Bottom rock temperature is 176°F. 

Systems Design Features: 

A second production well is being drilled, with greater production 

anticipated (casing will exceed 950 ft, closing off cold surface 

water). The first well will then be used for reinjection. Should 

we be unable to improve upon our 110°F resource with the #2 well, the 

following design specifications will be used: 

1. 348 gpm peak load pump, with a Nelson variable drive 

(110 gpm). 

2. Transmission line, 5-inch ID black iron bedded in insulation. 

3. In building heat exchangers, hot water boosted by gas and 

several multi-zoned fan-coil units. 

4. The current conventional system supplies approximately 

64,000 therms per year. The geothermal system should 

replace 44,000 therms, primarily in heating the water in 

the pool, boosting domestic hot water, and general space 

heating. 

34

Klamath County YMCA Project Page 2 

5. Project life-cycle estimates indicate 50-year term savings 

net of $4,950,000. 


Status: 

This straightforward application seeks to space/water heat a private 

recreation facility with geothermal fluid. The long-term benefits 

can profoundly impact the quality of recreation services available. 

For example, at present our swimming pool costs $1.15 per hour to 

heat. Conservative estimates, for 10 years hence, indicate a cost 

of $7.50 an hour. Since we are the only indoor teaching facility 

available year-round for a population of 60,000 people, this resource 

is critical. Future projections indicate an expense which would require 

this facility to be shut down. To a lesser degree, many other facilities 

and services could become so expensive to maintain as to be prohibitive. 

An alternative energy source then becomes critical to the life of 

our organization. 

We have completed our environmental study and predesign phases. Work 

on our second well is in progress. It is interesting to note that 

our second well, drilled 520 ft from our first well, is encountering 

virtually the same aquifer formations found in the first. We will 

improve our position through more accurate use of technical information. 

With Department of Energy support, i.e., teaming arrangements, 

management plan, technical assistance, and bid specification packages, 

we have grown as customers and general contractors. There does exist 

a learning curve which-can bring the process within the capability of a 

small private social service agency. 

Although technical advances are being made, problems exist in the 

fields of general contracting (a scarce resource in the geothermal 

field), accounting, legal, and engineering. Since the field is relatively 

new, general business support has no precedent and little in 

the way of "automatic" business procedures. As potential users become 

more sophisticated and knowledgeable as to their needs, we are able 

to turn a sellers market into a buyers market--a process which must 

occur if geothermal energy is to be put to widespread use. 

35

Project Title: Klamath Falls Geothermal Heating District 

Location: Klamath Falls, Oregon 

Principal Investigator: Mr. Harold Derrah, Assistant City Manager, 

^^Q2) 884-3161 

Project Team: 

- City of Klamath Falls 

- LLC Geothermal Consultants 

- Robert E. Meyer Consultants 


To provide for initial setup of the geothermal heating district. 

Initial project will provide heating to 14 city, county, state, 

and federal buildings. 


Project is within the Klamath Falls KGRA. The geothermal description 

of the KGRA is as follows: 

In general, the fractured basalts and cinders are highly porous, 

being capped by a nearly impervious zone of fine grained, 

lacustrine, palogonite tuff sediments and diatomite, referred 

to as the "Yonna formation" and locally as "chalk rock". 

This formation, Tst on the geologic map, is estimated to be 

30 to 150 feet thick in the urban area. It is also interbedded 

with sandstone or siltstone and fine cinders. 

The predicted temperatures for the project range from 200°F to 240°F, 

and the wells will be drilled to the approximate depth of 1,000 feet. 

Reported temperatures within the Klamath Falls area have been as high 

as 250°F, with flows being produced up to 700 gpm. 


The project will involve two production wells, each approximately 1,000 

feet deep, with temperatures ranging up from 200 to 240°F. There will 

also be a reinjection well for injection of geothermal fluids after 

passing through a central heat exchange facility. The heat exchanger 

facility is designed for plate exchangers, with the following specifications: 

Type - Single pass with 150 316 sst plates, EPDM gaskets 

Size - 9'3" long x r7" wide x 5' high. 

36

Klamath Falls Project Page 2 

Geothermal side - 219°F, inlet 

176°F, outlet 


350 gpm flow 

(1,000 gpm maximum flow) 

Secondary side - 200°F, outlet 

160°F, inlet 


378 gpm flow 

(1,000 gpm maximum flow) 

The estimated AT is 40°F. The estimated heating peak requirements 

for the initial project is 15.3 x 10^ Btu/hr. The system will involve 

the use of concrete conduits to allow for future expansion, longer 

life expectancy of the distribution system, and lower maintenance 

costs. Again, with the use of the conduit, expansion will be greatly 

facilitated. The estimated annual savings for the initial heating 

of the 14 buildings is $262,000, current dollar value. 


The project is initially for the establishment of a heating district 

that will provide geothermal heating to 14 city, state, county, and 

federal buildings. The intent of the project is to be the initial 

stage for a total urban heating district. Included within the project 

is the development of a master plan for the distribution lines, production 

sources, storage requirements, and peaking facilities. The 

initial project will involve two geothermal wells, a distribution line 

appropriately over-sized for future development, central heat exchange 

facilities, and domestic reheated water distribution system to the 

initial buildings. The geothermal distribution line will be placed 

in concrete conduit, which will provide for future growth, increased 

life expectancy, easy access for future maintenance and repairs, and 

also provide better assurance that groundwater will not provide a 

deteriorating factor to the life expectancy of the pipe. The project 

also envisions that after the water circulates through the plate heat 

exchange facility and has transferred the energy through the plate 

heat exchanger, the geothermal water will be reinjected to the geothermal 

reservoir for reheating and reuse. The Initial project is to 

generate a peak heating load delivery of 15.3 x 10^ Btu, with 755 gpm 

of estimated temperature of 200''F. The total estimated cost of the 

project is $1:4 million, with approximately 75% financed by the 

Department of Energy and the remaining match generated by local sources, 

The estimated savings in relation to natural gas costs is $262,000 

per year. 

37

Klamath Falls Project Page 3 

Status: 

At the date of this paper, the project is currently in the drilling 

status, with the completion of the conceptual design report and also 

an acceptable environmental report. As of the date of this report, 

the well has been drilled to 250 ft, and temperatures are at 137°F. 

It is envisioned that by the time this paper is presented one well 

will have been completed to approximately 1,000 ft, and the results 

of that particular well can be made available at that time. To date, 

the temperature gradient received In constant monitoring of the well 

within the range of 150 to 250 ft was approximately 1°F per 7 to 8 feet 

of drilling depth. From all Indications at this time, the well should 

prove out to at least the specifications drawn for the project. 

38

Project Title: Madison County Geothermal Project 

Location: Rexburg, Idaho 

Principal Investigator: Dr. J. Kent Marlor, Chairman, Madison County 

Energy Commission, (208) 356-3431 

Project Team: 

- Madison County; Kent Marlor, Program Director 

- American Potato Company; Eugene F. Berry, Deputy Program Director 

- Energy Services, Inc.; Dr. Jay F. Kunze, Project Manager 


To demonstrate the economics and feasibility of using a low-temperature 

geothermal resource for food processing and space heating applications. 


Madison County and Rexburg are at the eastern edge of the Snake River 

Plain, a plain that has recently been characterized as a young 

volcanic rift. Northeast trending faults, concentrated along the 

plain boundaries, are the source of many hot springs. The Snake River 

Plain has been the site of Intense bimodal basalt-and-rhyolite for 

the last ten million years. The youngest eruptions (Craters of the 

Moon and Cedar Butte) apparently occurred as recently as 1,625 years 

ago. 

Extensive exploration data include: reconnaissance-level geologic 

mapping and gravity surveys, electrical resistivity surveys, groundwater 

investigations, geochemical analyses of area wells, and a heat 

flow of 4 HFU. 

Further indications of warm water not far below the surface exist in. 

the Newdale area (9 miles northeast of Rexburg), with shallow 

(< 500 foot) wells producing 105°F and 97°F water. In the immediate 

vicinity of Rexburg there are several shallow wells, with temperatures 

in the 60's, the most promising of which is a 460-foot well with a 

surface temperature of 70°F. 

In consideration of the available data, a geothermal resource of 350 to 

450''F is believed to exist at a depth of 8,000 tp 9,000 feet below 

the Snake River Plain. The target depth of the production well will 

be between 5,000 and 7,000 feet, to encounter a resource of at least 

250°F. 


Two 1,500-ft hydrological test wells and production wells at 3,000 

and 6,000 feet are planned at this time. The deep well will supply 

250°F water to American Potato Company for use in food processing. 

39

Madison County Project Page 2 

Status: 

Two major heat exchangers, using fresh water, will discharge into 

blanching units used for boiler makeup water and supply heat to belt 

dryers, secondary dryers, and heat-filtered air entering the plant. 

Madison County will then receive the partially spent water from the 

processing plant, at 190°F, and will supplement it with water from the 

3,000-ft well, if required, Madison County will use the water for 

space heating purposes, using conventional heat exchangers. The annual 

savings in gas and oil would amount to an equivalent of 470 billion 

Btu (approximately 140 million kWh) by changing to geothermal energy. 

Final design will be based upon the temperature of resource encountered, 

flow rate, and economic analysis of these factors. 

The two 1,500-ft exploratory wells are being drilled at the time of 

this writing. 

40

Project Title: 

Location: 

Principal Investigator: 

Project Team: 

- Monroe City, Utah 

- Terra Tek, Inc. 


Direct Utilization of Geothermal Resources 

Field Experiments at Monroe, Utah 

Monroe City, Utah 

Mr. Duane Nay, Mayor, (801) 527-3511 

Utilize geothermal fluids from source of local hot springs to heat 

high school, city hall, and fire station. Install nucleus of district 

heating system for private and commercial usage. 


Sevier fault on Monroe-Red Hill KGRA Hot Spring, discharge 230 gpm 

at 148 to 165°F. Aquifer temperature is 169°F at 500 feet, increasing 

to 179°F at 1,400 feet. 


One production well = 

One Injection well = 

Geothermal fluid temperature = 

Circulating water temperature = 

Well pump capacity = 

Circ. pump capacity 

Load 

Candidate pipeline materials = 


1,471 feet 

800 feet (estimate) 

167°F 

155°F 

650 gpm 

650 gpm 

17 x 106 Btu/hr (with some fossil 

peaking assistance) 

asbestos cement and fiberglass reinforced 

plastic 

Monroe City is a community of 1,500 people, located 160 miles south 

of Salt Lake City, Utah. The local economy is based primarily on 

agriculture. The geothermal demonstration project currently underway 

in Monroe will explore the economic and technical viability of 

the application of a moderate-temperature resource for a district 

heating system. The project will entail the drilling of one production 

and one injection well. Geothermal fluid from the production 

well will be piped through a central heat exchanger and then to the 

injection well. The expected production temperature is 167°F, at 

650 gpm. The initial buildings to be heated will be the South Sevier 

High School, the Monroe City Hall, the fire station, and a number of 

small stores and residences. The system will be capable of being 

expanded to include the major areas of Monroe, and it is estimated 

that the total system will be capable of a load of 12,000 kW. 

41

Monroe City Project Page 2 

Status: 

The principal investigator is Mr. Duane Nay, Mayor of Monroe City. 

Terra Tek, Inc., Salt Lake City, Utah, has responsibility for implementing 

the project, under the direction of Mr. Roger Harrison. 

A 1,471-ft production well has been drilled and flow rates up to 

370 gpm and temperatures to 167°F have been obtained during preliminary 

pump testing. Preliminary system design and costing and planning 

for injection well drilling is underway. Further pump testing of the 

aquifer is also planned. 

42

Project Title: Water and Space Heating for a College and 

Hospital by Utilizing Geothermal Energy at 

Corsicana, Texas 

Location: Navarro College and Navarro Memorial Hospital 

Corsicana, Texas 75110 

Principal Investigator: C. Paul Green, Institutional Development Director 

Project Team: 

Navarro College, (214) 874-6501 

- Navarro College, Corsicana, Texas - Prime Contractor and User 

Facility 

- Navarro Memorial Hospital, Corsicana, Texas - Using Facility 

- Radian Corporation, Austin, Texas - Geothermal Consulting Engineers 

- H. H. Hardgrave, Corsicana, Texas - Drilling Consultant 

- Ham-Mer Consulting Engrs, Austin, Texas - HVAC Engineers 


The objective of this project is to demonstrate the economic and 

technical feasibility of direct utilization of geothermal energy. 

To meet this objective, this project is designed to decrease the 

dependence of Navarro College and Navarro County Memorial Hospital 

on fossil fuel by making maximum use of the low-temperature geothermal 

resource for water and space heating. 


Well tests have produced sustained flow rates of 315 gpm of 125°F 

water, at about 5,300 ppm total dissolved solids. The producing 

zone is 2,400 to 2,600 feet below the surface. The source of the heat 

is faulting associated with the Ouchita fold belt, which outcrops 

in Arkansas and underlies much of central Texas. The Woodbine Formation 

is the groundwater reservoir that makes up the aquifer. Hydraulic 

interconnection of deeper and shallow formations provided by the 

Mexia-Talco fault system is the factor responsible for the area's lowtemperature 

geothermal value. 


One 2,600-ft production well provides the required flow for this pro- 

• Ject. Flat-plate heat exchangers will be used to achieve maximum geoheat 

utilization and for ease of cleaning. Geothermal fluids will not 

be vented to the atmosphere so as to control corrosion and scaling 

phenomena. At peak winter heating periods, the geothermal heating 

system will deliver approximately one million Btu/hr to the college's 

Student Union Building (SUB), and about 3,5 million Btu/hr (peak) to 

the hospital water and space heating systems. This load is represented 

by a fluid temperature drop of 25°F at 315 gpm, and will reduce the 

college and hospital natural gas heating loads by 87 and 44 percent, 

respectively. The geothermal fluid will be disposed of by injection 

into a suitable horizon via a second well. 

43

Navarro College and Memorial Hospital Project Page 2 


Status: 

The purpose of this geothermal project is to retrofit a college SUB 

and county hospital space and water heating systems to use geothermal 

energy, thereby reducing their dependence on fossil fuels. The 

geothermal heating system will supply heat to the domestic water 

system, as well as the forced air heating and outside air preheating 

systems of the college SUB and hospital. At present, heat input to 

these systems is accomplished via steam provided by low-pressure, 

natural gas-fired boilers. These boilers will be maintained in place 

as backup and augmentation. 

Readily available commercial piping, pumps, valves, controls, flatplate 

heat exchangers, and insulation will be utilized. However, even 

though initial geochemistry has shown the Corsicana geothermal fluids 

to be relatively noncorrosive, a short series of field corrosion tests 

will reveal the most acceptable system materials. 

The final phase is a one-year operational demonstration phase, during 

which potential geothermal users will be encouraged to visit and 

observe the geothermal heating system. 

A submersible production pump has been set at 1,000 feet, and pumped 

at 315 gpm. Injection well drilling will commence in September 1979, 

and system preliminary design will begin in October 1979. 

44

Project Title: Direct Utilization of Geothermal Energy for 

Food Processing at Ore-Ida Foods, Inc. 

Location: Ore-Ida Foods Processing Plant, Ontario, Oregon 

Principal Investigator: Mr. Robert W. Rolf, Director Technical Services, 

Project Team: 

Ore-Idaho, Inc., (208) 336-6238 

- Ore-Ida Foods, Inc. 

- CH2M Hill, Inc. 

- GeothermEx, Inc. 


Locate and develop geothermal resource of 800 gpm at 320°F. Retrofit 

existing plant for potato processing, space heating, and hot potable 

water. 


Snake River Basin, (predicted) 320°F at 7,000 feet. 


Two Production Wells 

One Injection Well 

Central Heat Exchangers 

Fluid Transmission Pipeline 

Geothermal Fluid Temperature = 150°C (300°F) 

Injection Fluid Temperature = 55''C (130°F) 

Total Well Capacity = 800 gpm 

Pipeline - Buried insulated steel 

Maximum energy utilization via cascading 

System Capacity '\- 64 x 10° Btu/hr 

Estimated Annual Fuel Savings - 97,200 MWh 


Status: 

Ontario, Oregon is located just across the Oregon-Idaho border, 57 

miles northwest of Boise, Idaho. The existing Ore-Ida Foods, Inc. 

plant processes potatoes, corn, and onions. It is currently dependent 

on natural gas and oil for process heat. The plan for this demonstration 

program is to substitute geothermal energy for the potato processing 

heat and other heat loads of about 97,000 MWh annually (33.2 x 10^0 

Btu/yr). 

An environmental report has been prepared which examines the impacts 

the project will have upon the environment and the Ontario area. 

45

Ore-Ida Foods Project Page 2 

A seismic survey has been conducted to supplement existing geologic 

and geophysical data. Based upon all the data available, two production 

sites have been located on the Ore-Ida factory property. Drilling 

of the first production well commenced on August 19, 1979, and is 

expected to be at the target depth of 7,000 feet in 45 to 60 days. 

The preliminary system design is underway. Equipment and material 

selections are being made and piping and heat exchanger locations are 

being laid out. Final design is expected to commence in late 1979. 

46

Project Title: Pagosa Springs Geothermal Distribution and 

Heating System 

Location: Pagosa Springs, Colorado 

Principal Investigator: Fred A. Ebeling, Planning Administrator (303) 264-5851 

Project Team: 

- Town of Pagosa Springs 

- Archuleta County 

- School District 50 Joint 

- Coury ^nd Associates, Inc. 

Project Objective: To provide the community with a means of using its 

natural hydrothermal resource for space heating at minimal cost to 

users and reduce local dependency upon fossil fuels. This project 

will determine the best methods of utilizing the hydrothermal resource, 

demonstrate the practicability of community space heating systems, 

and provide the basis for future expansion. 

Resource Data: The geothermal resource in Pagosa Springs has been used on 

an individual basis since the early 1900's. Since then, nearly 30 

wells have been drilled for heating and recreation purposes. These 

wells are drilled to depths of less than 500 feet and produce waters 

ranging in temperature from 130° to 170°F. The water quality of the 

resource is highly site specific. Some of the wells produce warm 

water which nearly meets the national drinking water standards. Others 

contain higher concentrations of dissolved solids similar to those of 

the production formation, the Mancos Shale. 

System Design Features: Flow from several existing wells in the town can 

be used to supply the entire heating needs of the system. It is 

expected that with proper pretreatment the geothermal fluids can be 

pumped through the distribution system directly to the individual 

users. The geothermal fluid will then be collected and returned to a 

central location for either reinjection or surface discharge to the 

Sah Juan River, depending on the water chemistry. In the past, all 

geothermal fluids, including the natural hot springs, have been discharged 

to the San Juan River. 

It is estimated that an average flow rate of 500 gpm is required for 

the system. A AT of 25° is anticipated at design conditions. The 

estimated annual cost for the fossil fuels to be replaced by the geothermal 

system is about $70,000. 

Project Description: The Pagosa hot springs have been used for therapeutic 

purposes since prior to the coming of the white man. In this century, 

the underground reservoir has been tapped by wells and the hot water 

used for heating purposes in a relatively unsophisticated manner, 

which has presented corrosion and scaling problems. Characteristics 

of the resource have never been quantified--area, depth, source of 

47

Pagosa Springs Geothermal Project Page 2 

heat, pressures, temperatures, water quantity, recharge mechanisms, 

specific geology, etc. The first phase of this project is to 

quantify characteristics of the geothermal reservoir. This provides 

a basis for determining its .potential applications and the design 

of a system for practical utilization. 

Actual construction and placing the system in operation is scheduled 

for completion by late 1980. The Town of Pagosa Springs will then 

operate and maintain the system. Operational data will be collected 

to allow ongoing evaluation of the system, to gain further knowledge 

concerning the resource characteristics and potential future capabilities, 

At present, the project is in the early stages and specifics are not 

as yet determined. In general, all public buildings in the town 

(courthouse. Town Hall complex, schools, etc.) will be heated using 

geothermal energy. Location of these buildings will basically determine 

routing of the distribution piping. Other buildings, commercial 

or residential, which can logically be served from the distribution 

pipelines, may tap on. The piping will be located along easements, 

alleys, or streets provided by the town, county, or school district. 

User fee arrangements have yet to be determined. 

Several options are available for the heat distribution medium. The 

hot geothermal water may be used directly from the underground reservoir 

or it may be chemically treated to counteract corrosive and/or scaling 

difficulties. Or, a closed, fresh water loop may go to the user facilities 

after heating by a heat exchanger, which Isolates the geothermal 

water. 

Options also exist for access to the subsurface geothermal reservoir. 

Existing, relatively shallow, wells, may be used. Or, new wells may 

be drilled to tap intermediate depths. Or, a combination of wells 

may be used. Final system design will involve consideration of several 

interdependent factors for optimum practicality. 

The total cost of the project is estimated at $1,003,000, of which DOE 

will provide $779,000 and local community $224,000. The amount shared 

by the local community is comprised of in-kind contributions of wells, 

rights-of-way, easements, and work by local people. The Town of 

Pagosa Springs has been designated as the local lead entity by its 

partners, Archuleta County and the School District. Local control is, 

by agreement among the three entities, handled by an advisory committee 

consisting of interested and qualified citizens. 

Status: The Environmental Report and the resource evaluation flow-test plan 

have been submitted to DOE-ID for review. Well monitoring equipment 

is being installed. A file of existing hydrological and geological 

data has been compiled. The project is coordinating with appropriate 

regulatory agencies and a survey of prospective users has been conducted. 

The conceptual design is ready for review. 

Public meetings, news releases, and radio interviews have been used 

to keep the public informed. General public attendance at the Advisory 

Committee meetings is increasing. 

48 

.

Project Title: Multiple Use of Geothermal Energy at Moana KGRA 

Location: Reno, Nevada 

Principal Investigator: Dr. David J. Atkinson, President 

Hydrothermal Energy Corporation 

(702) 323-2305; (213) 654-5397 

Project Team: 

- Hydrothermal Energy Corporation, Developer and Heat Supplier 

- Oak Grove Investors, Principal Heat User 

- S.A.I. Engineers, Engineering Design and Construction 

- W. L. McDonald & Sons, Drilling 

- William E. Nork, Inc., Logging and Testing 


Thermal waters of the Moana KGRA in Reno have been used over several 

decades for heating buildings and swimming pools. 

We shall use these waters for heating space and domestic hot water 

in the Sundance West apartment complex nearby. 

To increase utilization of available heat and aid disposal of cooled 

geothermal fluids, we shall add whichever auxiliary uses prove most 

feasible after space and water heating is completed. 


The resource at Moana KGRA underlies part of southern Reno, though 

its exact limits have not been defined. Cool or cold water wells 

surround the general area of thermal water, but these wells are not 

spaced closely enough to map a boundary. 

Geologic conditions are relatively simple. Valley fill in the area 

is generally 600 to 2,000 ft thick and consists of very young gravels, 

sands and clays. The hot water presently used at Moana comes mostly 

from shallow aquifers in this sequence, usually below a characteristic 

blue clay aquiclude. 

Below this valley fill are Tertiary volcanics, principally andesite. 

Gravity data provide a straightforward indication of depth to this 

volcanic "basement", and, when combined with a detailed structural 

analysis, show that the shallow hot water reservoirs in the valley 

fill overlie part of a clearly defined upfaulted block. 

Fault and fracture patterns show three main sets trending approximately 

N, N 40° E and N 35° W, The sense of relative displacement on these 

faults suggests they are conjugate shears (N 40° E and N 35° W), 

bisected by extension fracturing and normal faults that trend north. 

49

Moana KGRA Project Page 2 

Fracture zones and intersections in the volcanic basement may provide 

the best targets for high flow rates in our production wells. 

Temperatures in some existing wells are close to boiling point, but 

more usually are in the range 140 to 190°F, with only about 1,100 ppm 

total dissolved solids. 


Two production wells about 1,000 ft deep will be drilled near the 

apartment complex where the heat will be used. The geothermal fluids 

will be piped underground to newly installed shell and tube heat 

exchangers in the existing boiler rooms. 

The present heating system, using circulating hot water, was specifically 

intended by the creator and designer of the apartment complex, 

Mr. Larry Freels, to take advantage of the local geothermal energy. 

The task of retrofitting will accordingly be relatively straightforward. 

The existing natural gas boilers will be retained both as permanent 

backup and to handle peak loads. 

Temperature drop in the geothermal water will be about 60°F. An 

average flow of about 70 gpm (180°F) will be needed to supply the 

major part of the heating load, which is 176,000 therms annually. 

Peak flow will probably be about 250 gpm. 

The saving of fossil fuel energy (about 3.5 x loH Btu over twenty 

years) is quite significant, and will be increased by auxiliary uses 

of the heat remaining in the geothermal water after space and water 

heating. 


The first stage of the project involves environmental clearances and 

obtaining the numerous permits that are required. 

Then, by integrating data on geology, hydrogeology, geochemistry, geophysics, 

economics, and engineering, we shall select the first well 

site and design the well. 

We shall drill a test production well, log it, and test selected 

intervals for flow rates and temperature. From the results, we shall 

design the well completion to maximize heat extraction. 

From results of the pump tests, we shall finalize design of the production 

and distribution system, and the retrofit heat exchangers 

and related equipment. 

Samples of the geothermal water will enable us to select, and obtain 

permits for, the most appropriate disposal method. 

A second production well will next be drilled, utilizing the experience 

gained in the first. 

50

Moana KGRA Project Page 3 

Status: 

Installation of the burled pipelines will follow, taking geothermal 

water into and out of the apartment complex boiler rooms. Heat 

exchangers will be installed in these, upstream of the present boilers 

where the cold return water enters after circulating through the 

buildings. 

After testing and optimization and detailed analysis of the engineering 

results of the Installation, the system will run on a routine commercial 

basis. 

The best technically and economically feasible auxiliary applications 

will then be selected, and used to extract more heat from the geothermal 

water after the space and water heating load is handled. 

An Important aspect of the project is a program of public information 

to convey broadly how simple the concept of direct use of geothermal 

heat is, and exactly how this project was done, and what results we 

obtained. 

At the time of writing, we are only four weeks into the project, and are 

working on the first stage. Drilling should begin before the end of 

this year. 

51

Project Title: Geothermal Application of the Madison Aquifer 

for St. Mary's Hospital 

Location: St. Mary's Hospital, Pierre, South Dakota 

Principal Investigator: James Russell, St. Mary's Hospital Administrator 

Project Team: 

(605) 224-5941 

- St. Mary's Hospital 

- Kirkham, Michael and Associates, Engineer 

- Sherwin Artus, Reservoir Consultant 

- Dr, J. P, Gries, Geologist 


Demonstrate that 106°F water can be used economically to heat buildings 

and also to preheat domestic hot water. 


The 2,100-ft well which taps the Madison aquifer is located on a 

vacant lot adjoining a residential neighborhood and across the street 

from the hospital complex. The site overlooks the Missouri River. 

Well test data indicate a static pressure of 480 psig maximum, and 

a flow of 375 gpm, with 27 psig, at 106°F. 


The system has been designed for 350 gpm flow at 105°F, producing 

4,375,000 Btu/hr. The maximum supply water temperature out of the 

heat exchanger is expected to be 100°F. A corrosion and water 

quality report was completed by Dr. Howard and Dr. Carda of Rapid 

City, South Dakota. This report indicates that type 315 stainless 

steel is the recommended material for the thin wall plate fin-type 

heat exchangers. 


(See attached well house and exchanger building schematic.) The 

system's three heat exchangers will provide heat for three existing 

hospital systems and will also serve the new hospital wing presently 

under construction. The existing hospital systems are: 1) space 

heat in existing fan coil units now used only for air conditioning; 

2) space heat for the high volume of outside air (makeup air ventilation) 

that is required in some areas of a hospital; and 3) preheating 

of domestic hot water. The well is located across the street from 

the hospital. The heat exchangers will be located in a small building 

at the well site. 

52

St. Mary's Hospital Project Page 2 

Status: 

a) Heat Exchanger Design: Heat exchangers will be in accordance 

with the following design conditions: 

Flow Ent Leav 

No. Function Fluid gpm °F °F 

1. Building Heat Geothermal = 350 105 80 

Closed Loop 

Heating Water = 350 75 100 

2. Preheat Dom HW Geothermal = 350 80 75 

utilizing geo- Domestic Water = 76 55 78 

thermal discharge 

from exchanger #1 

3. Preheat dom HW Geothermal = 97 105 70 

(boost from §2 Domestic Water = 76 55 100 

and full preheat 

when #1 is unloaded) 

b) Makeup Air System Retrofit: A high volume of fresh air must be 

continuously Introduced into certain areas of a hospital. This 

requires raising the outside air temperature to room temperature. 

Using the existing 6-row chilled water coil (15,650 CFM), the 

geothermal water supply flow would be 90 gpm at 100°F, and the 

leaving water temperature would be 64.5°F. 

c) Fan Coil System Retrofit: The heating system in the existing 

hospital is basically steam perimeter radiation. The fan coil 

system was added to provide air conditioning. Chilled water at 

the average temperature of 50°F is circulated in the summer, to 

provide approximately 57 to 59°F supply air off the coils. In 

the winter time, 100°F water will be provided to these coils, to 

produce 87°F heated air, which is adequate to heat the spaces 

served during outside temperatures of approximately 2°F and above. 

d) New Building Heatinq: 155 gpm from heat exchanger #1, representing 

2,000,000 Btu/hr, will be available for use in the new hospital 

addition that is presently under construction. The new heating 

system is designed to utilize the geothermal heat source. (See 

new building heating schematic.) 

The well is completed. Retrofit of the existing mechanical system 

will go out for bids at the end of August or early September. 

53

'4 

]^ 

W^^ 

'!-/..-'

-LPS" 

•LP/f—O e-HW/i^ 

L_ 1 ^ 

STEAM BACK-UP I 

HEAT EXCHANGER 

preheated dom. 

hw from exchanger 

building 

from ond fo heat 

exchanger no. I 

In exchanger 

building 

HEATING HW PUMPS 

( I STANDBY) 

to other colls 

•i- 

DUCT HEATING 

COIL(TYR) 

HiVH ^ fi---j>^]—A cwv? -» *--cjy/?—• 

NEW BUILDING HEATING SYSTEM SCHEMATIC 

55 

S

Project Title: Susanville Energy Project - Direct Utilization 

of Geothermal Energy 

Location: North end of the Honey Lake Valley, Lassen County, 

California 

Principal Investigator: Philip A. Edwardes 

(.916) 257-7259 

Project Team: 

- Aerojet Energy Conversion Company 

- Donna Benner, Drury System Design 

- Monte Koepf, Koepf and Lange, Engineering 

- Fred Longyear, Lahontan, Inc., Technical Advisor 

- Johan Otto, Carson Development, Management Information System/ 

Construction Management 

- Dr. Subir Sanyal, Energetics Marketing & Management Associates, Ltd., 

Reservoir Evaluation/Management 


To displace fossil fuels and create employment. Program will heat 17 

public building complexes. Effluent fluids will be cascaded through 

a Park of Commerce. Ultimately the heating of all commercial buildings 

and private homes within the City of Susanville may be feasible. 


Most of the temperature gradient holes developed penetrated alternating 

layers of basalt and mud flow (ash flow) agglomerates. Some holes 

encountered alluvial conglomerates. Correlation of lithological strata 

from one hole to another indicates faulting. This confirms the surface 

evidence of extensive faulting in the area. Electrical logs through 

the basalt layers suggest fracturing at the upper and lower limits of 

the layers, indicating these basalt layers, as well as the agglomerates 

and conglomerates, may be potential reservoir units. 

Ten holes were drilled within the city boundaries and its immediate 

surroundings, ranging in depth from 135 m to 640 m. Six existing 

private wells are also within the area. Temperatures varied between 

35 and 75°C. Several holes, notably in the southwest portion of the 

reservoir, display marked temperature reversal, with depth of 100 to 

150 m in the holes with the higher temperature. In the north part of 

the reservoir area, reversal takes place much deeper, and the temperature 

zone is also thicker. 

Resource data to date suggest a temperature of 75°C possible, with 

individual well flow between 300 and 400 gpm; a flow rate of well 

over 2,000 gpm is considered feasible, pending final evaluation of 

BuRec resource work. 

56

Susanville Energy Project Page 2 


It is projected that there will be 3 production wells, capable of 

350 gpm, pumping from a depth of 150 m x 200 m at 72°C, producing 

20,000,000 Btu/hr. Two reinjection wells are planned. Water quality 

data to date suggests total dissolved solids of less than 1,000 PPM 

and pH of 7-7.5. The heat requirement of the 17 building complex 

(320,000 sq ft) is 12,000,000 Btu/hr; the effluent fluid reaches the 

park at a temperature of 110°F. A heat pump will be incorporated 

within the system for peaking purposes, enabling further fossil fuel 

displacement, and also minimizing the necessity for further wells. 

A relatively limited use of heat exchangers is visualized in the 

retrofits. Heat exchangers will be utiTized only where damage to the 

existing hardware could be caused by the geothermal fluids. In several 

cases, a direct hookup will be possible; in other buildings fan coils 

will be used. 

The economic model allows for wells to be replaced at the rate of 25% 

every 7 years. Initial indications are that a price to the consumer 

of $2.75 per million Btu could be possible. This figure could dramatically 

change with full utilization of the effluent fluids by the 

Park of Commerce. 

The main transmission lines are capable of an optimum flow of 2,000 

gpm; the 12-inch transmission line will be insulated, and the 12-inch 

return line uninsulated. 


The Susanville project envisions in its initial phases the development 

of a heating district to heat 17 public building complexes and to 

cascade the effluent heat through a Park of Commerce. 

The City of Susanville, in 1974, recognized the necessity to hold 

down the escalating cost of heating to the local population and to 

create job opportunities (the local unemployment was reaching a peak 

of 20% in winter months). The existence of a resource had been 

identified and utilized in a limited manner from the 1920's; its 

extent and real potential was unknown. The city believed that it was 

beyond the capacity of private enterprise to establish and develop 

the resource, so by resolution of Council, expressed its intent to 

develop the resource potential on behalf of the maximum number of 

residents for their maximum benefit. It was because of this expressed 

intent that Public Law 94-156 was passed, and BuRec was authorized and 

funded by Congress to evaluate the resource potential on behalf of 

the city. This extensive program is currently ongoing and is proving 

to be successful in its objective. 

It was deemed expedient that the initial development would address 

publically held buildings, thus spreading the cost savings benefits 

to the population in general. It was also anticipated that it would 

be easier to attract grant funds for this objective. The Park of 

Commerce would be developed concurrent with the heating district. 

57


The potential for replicating the program in many western rural 

areas was identified, and this formed part of the basis of justification 

of the project. 

In January 1978, a proposal was submitted to DOE which projected a 

DOE contribution of $2.4 million and a City share of $1.9 million. 

The program was expected to extend over a 33-month period. Phase I, 

the design and engineering effort, is currently under contract, with 

Phase II, the construction phase, hopefully under contract in time 

to develop the first production well in December 1979. The City and 

its team members believe they have the capacity to have fluid flow 

and utilization by December 1980. 

The Park of Commerce is being promoted and developed independently of 

DOE, but, at the same time, the City is under contractural obligation 

to DOE to do so if deemed feasible. Currently the City is negotiating 

for land suitable for such a park (200 to 300 acres). It is the 

City's intent to secure options on behalf of its nominees (identified 

industry) but not to be involved in land purchases itself. The City 

will and has successfully identified potential long-term loan sources 

for the development of streets, utility reticulation, and sewerage 

system for the park; the repayment will come from the developers and 

operators within the park. 

The'City intends that the Park of Commerce will have an agricultural 

bias, feed mill, greenhouses, and confined animal raising units. Some 

heat augmentation of the residual effluent from the heating district 

will be necessary for refrigeration, air conditioning, and sterilization 

of wool, etc. Various alternate energy sources are being investigated 

(wood waste, city refuse, and methane from the animal fattening 

units) to accomplish this. 

The intent of the City of Susanville is that eventually it will develop 

a heating district encompassing all buildings within the city. It is 

likely that a high percentage of Main Street commercial buildings 

could be heated by December 1981; progress to encompass single family 

homes could be considerably slower. It is recognized that the geothermal 

resource in itself may be insufficient for this ambitious program; 

however, the City believes that the cost effectiveness of utilizing 

wood waste from the nearby forest areas will allow it to continue 

in its objective of being self-sufficient in energy for heating purposes. 

Importantly, the City has unanimous support in its endeavor from the 

local population. 

In recognition of the fact that a geothermal resource is finite by 

definition, the City introduced an ordinance to insure orderly and 

efficient utilization of the resource for the maximum benefit of the 

residents of the city. It is the declared intent of Council to make 

geothermal energy available to private enterprise at the lowest cost 

possible. The City's ownership of the total supply and distribution 

system will enhance this position. 

58


Status: 

Phase I: Under DOE contract since March 1, 1979 for design, 

engineering, and resource evaluation. Major permitting has been 

completed. Initial design criteria has been transmitted to engineers, 

Program to date on schedule. 

Phase II: Construction period, hopefully, will commence in December 

1979, with development of the first production well. Pipeline and 

storage tank construction is anticipated to commence in May 1980, 

concurrent with retrofit. First flow to part of the system is anticipated 

by December 1980, Completion and checkout is anticipated 

by June 1981. 

59

] ^ ITffl^SSH 

'(gSPW-

a 

Project Title: Direct Utilization of Geothermal Energy for Space 

and Water Heating at Mariin, Texas 

Location: Torbett-Hutchings-Smith (THS) Memorial Hospital 

Mariin, Texas 76661 

Principal Investigator: J. D. Norris, Jr., Administrator 

Project Team: 

^ Resource Data: 

THS Memorial Hospital, (817) 883-3561 

- THS Hospital, Mariin, Texas - Prime Contractor and User Facility 

- Radian Corporation, Austin, Texas - Geothermal Consulting Engineer 

- Ham-Mer Consulting Engineers, Austin, Texas - Economic Evaluation, 

Operation and Maintenance 

- Layne Texas Company, Dallas, Texas - Well Drilling 

- Spencer Associates, Austin, Texas - Architectural 


The objective of this project is to demonstrate the economic and technical 

feasibility of direct utilization of geothermal energy. To meet 

this objective, this project is to augment the space and water heating 

requirements of the THS Memorial Hospital in Mariin, Texas, with geothermal 

energy. 

Well tests have produced flow rates of over 300 gpm of 153°F water, 

•y at about 4,000 ppm total dissolved solids. The producing zone is 

3,615 to 3,885 feet below the surface. The source of the heat is 

faulting associated with the Ouchita fold belt, which outcrops in 

Arkansas and underlies much of central Texas. The coarser-grained 

sandstones (especially the Houston member of the Travis Peak Foundation) 

are the groundwater reservoir that defines the aquifer. The factor 

which is responsible for the area's geothermaT value is the hydraulic 

interconnection of deeper and shallow sandstones provided by the 

Mexia-Talco fault system. 


One 3,885-foot production well will provide more than the required flow 

for this project. Flat-plate heat exchangers will be used to ach'ieve 

maximum geoheat utilization and for ease of cleaning. Geothermal 

fluids win not be vented to the atmosphere so as to control corrosion 

and scaling phenomena. At peak winter heating periods, the geothermal 

heating system will deliver approximately 2.5 million Btu/hr to the 

hospital heating load. This load is represented by a fluid temperature 

drop of 45°F at 110 gpm, and will reduce the THS Hospital natural gas 

« consumption by 85 percent. The geothermal fluid disposal system design 

is yet to be defined. 

V 

61

THS Memorial Hospital Project Page 2 


Status: 

The purpose of this geothermal project is to retrofit the 130-bed 

hospital space and water heating systems to use geothermal energy, 

thereby reducing its dependence on fossil fuels. The geothermal 

heating system will supply heat to the hospital domestic water system, 

as well as to the 130°F space heating and outside air preheating 

systems. At present, heat input to these systems is accomplished via 

steam provided by a low-pressure, natural gas-fired boiler. This 

boiler system will remain in place as backup and augmentation. 

Readily available commercial piping, pumps, valves, controls, flatplate 

heat exchangers, and insulation will be utilized. However, 

even though initial geochemistry has shown the Mariin geothermal 

fluids to be relatively noncorrosive, a short series of field corrosion 

tests will reveal the most acceptable system materials. 

The final phase is a one-year operational demonstration phase, during 

which potential geothermal users will be encouraged to visit and 

observe the geothermal heating system. 

A 3,885-foot deep production well was completed and tested in July 1979. 

Preliminary heating system design is underway, and the Preliminary 

Design Review is anticipated to be held in November 1979. 

62 

i


Location: 

Floral Greenhouse Industry Geothermal Energy 

Demonstration Project 

567 West 90th South, Sandy, Utah (15 miles south 

of Salt Lake City center) 

Principal Investigator: Ralph M. Wright, Chairman of the Board 

Project Team: 

Utah Roses, Inc, (801) 295-2023 

- Utah Roses, Inc., Sandy, Utah 

- Energy Services, Inc., Idaho Falls, Idaho 


To demonstrate to the public the potential offered by geothermal space 

heating in a highly populated area, by using geothermal heating in a 

commercial application. 


A large area of the southeast portion of the Salt Lake Valley appears 

to be underlaid by a source of warm water. Crystal Hot Springs, 

approximately 6 miles south, flows hot water at 180°. Several wells 

in the area of Utah Roses have shows of warm water, including one 

within 100 yards of the proposed site, which has 93°F water at 875 

feet. There is evidence of a fault running east-west at our location. 

These indications, plus the normal temperature gradient, lead to an 

expectation of water at 150 to 180°F at 3,000 to 4,000 feet. Since 

no drilling below 1,000 feet has occurred in our area, flow rates and 

actual temperatures are difficult to project until actual drilling 

can take place. 


One well is projected to a 4,000-ft depth, with possibly a second well 

for reinjection. However, the primary plan is to discharge the water 

into a nearby irrigation canal, if water quality is high enough. Heat 

exchange will be dependent on water quality and temperature. Plans 

are to keep the water under pressure and run it through water/air heat 

exchangers in the greenhouse, with the air being distributed through 

jjolyethelene tubes located near ground level throughout the greenhouse, 

If sufficient flow and temperature are achieved, the entire heat load 

of the greenhouse will be taken over by geothermal, with an annual 

saving of $100,000, 

63

Utah Roses Project Page 2 


Status: 

A 4,000-ft well is to be drilled at the present site of Utah Roses, 

Inc, a 250,000 sq ft greenhouse which is producing cut roses for 

the national floral market. If water of sufficient temperature and 

quantity is developed, the water will be used to heat the greenhouse, 

replacing the current natural gas/oil usage. Since Utah Roses is well 

known in the floral Industry, with two of its officers serving as 

officers in national floral trade associations, a considerable amount 

of publicity has been and will be generated for geothermal energy in 

an industry that has a high potential for using geothermal energy. 

The Environmental Report has been prepared and approved, the well 

design is completed, and the bid package has been sent to prospective 

drilling contractors. It is planned to begin drilling during September. 

64 

\

Project Title: Direct Utilization of Geothermal Resources, 

Field Experiment at the Utah State Prison 

• Location: Draper, Utah; approximately 22.5 km.(14 miles) 

south of Salt Lake City. 

c 

Principal Investigator; Jack Lyman, Director, Utah Energy Office, 

(801) 533-5424 

Project Team: 

- Utah Energy Office 

- Utah Department of Social Services 

- Utah State Building Board 

- Utah Geological and Mineral Survey 

- Terra Tek, Inc. 


To demonstrate the economic and technical viability of using a lowtemperature 

geothermal resource in a variety of direct applications 

at the Utah State Prison. 


The site of the Utah State Prison PON is located in the southern portion 

of Salt Lake County, near Draper, Utah. Located just west of 

> the Wasatch Range, the resource is within the Basin and Range physiographic 

province. The surface expression of the resource is known 

as Crystal Hot Springs, and is located on the northern flank of the 

* East Traverse Mountains; a horst that is intermediate in elevation, 

between the Wasatch range to the east and the valley grabens to the 

north and south. The northern flank of the Traverse Range is bound 

by a series of northeast striking normal range front faults, having 

a combined displacement of at least 900 m (3,000 ft). The thermal 

springs are located between two of the range front faults that are 

intersected by a north-northeast striking fault. Only 25 meters 

(80 ft) of basin alluvial material covers the bedrock surface in the 

immediate vicinity of the springs. The maximum measured temperature 

of the resource is 85°C, and total surface discharge is approximately 

35 1/sec. (1.25 ft^/sec). The total dissolved solids content of the 

spring water is on the order of 1,500 mg/l. 


The preliminary system design for the Utah State Prison minimum security 

block includes plans for a space heating system, with a design load 

of 750 kW and a culinary water heating system with a design load of 

500 kW. The inlet temperature for both systems is 90°C; the outlet 

^ temperature is 75°C (T = 15°C) for the space heating system and 65°C 

(T = 25°C) for the water heating system. Together, these systems 

V, will require a design flow rate of 17 kilograms per second (270 gpm) 

and an average requirement of 5 kilograms per second (80 gpm). 

65

Utah State Prison Project Page 2 

One production well and one injection well (If needed) are anticipated, 

Siting of the production hole will be based on the results of a 

detail gravity survey and thermal test hole drilling program. The 

injection well will be drilled in the event that water quality 

parameters preclude surface disposal, in which case the water could 

be disposed of in near surface alluvial aquifers. 

The conversion of the minimum security block to a geothermal heat 

source will result in a 10 to 25% reduction in the prison's use of 

natural gas and fuel oil. 


Status: 

The project is designed to provide geothermal space and water heating 

systems for the minimum security block of the Utah State Prison. 

Future expansion of the project may include the extension of these 

services to other buildings, as well as the use of the thermal water 

for a variety of other direct applications at the prison dairy and 

slaughterhouse. Where possible, the geothermal fluids may be used 

to heat greenhouses and irrigate crops. 

The first phase of the project has just begun. The detailed gravity 

survey is in progress and plans are being made for a test hole drilling 

program. 

66

V 


Location: 

Geothermal Heating of Warm Springs State Hospital, 

Montana 

Warm Springs State Mental Hospital, Deer Lodge 

County, Montana 

Principal Investigator: M. Eugene McLeod, Project Manager 

(406) 494-6420; FTS-587-6402 

Project Team: 

- MERDI, Inc. 

- Energy Services, Inc. 

- CH2M Hill, Inc. 

- State of Montana 


The objective of this program is to develop the geothermal resource 

at Warm Springs for domestic water and space heating. 


The Deer Lodge Valley is within the Northern Rocky Mountains physiographic 

province and is bordered on the east by low (generally below 

8,000 ft), rolling hills known locally as the Deer Lodge Mountains. 

The western boundary consists of the rugged, glaciated Flint Creek 

Range, with elevations up to 10,171 feet (Mount Powell). The Anaconda 

Range encloses the valley on the south and the Garnet Range is 

located to the north. The valley consists of high terraces that slope 

downward from the mountain peaks and terminate above low terraces that 

grade into the Clark Fork flood plain, which forms the valley floor. 

This basic topography has been modified by the formation of coalescent 

fans and glacial moraines at the mouths of the tributary valleys and 

canyons. This modification is especially evident on the west side of 

the valley. 

The valley is predominately filled with Tertiary sedimentary strata 

derived from the surrounding mountains. This strata has a diverse 

lithology composed primarily of interbedded limestone, shale, sandstone, 

volcanic debris, and sand. It appears to be at least 1,600 feet thick 

northwest of Deer Lodge and is overlain by 300 feet of Pliocene channel 

sand and gravel. The strata also contains bentonitic clay beds, pebble 

conglomerate, cobbles, and granitic debris. The maximum thickness of 

the valley fill may be as much as 5,500 feet east of Anaconda. The 

Tertiary valley fill is estimated to be approximately 2,200 feet thick 

in the area of Warm Springs. 

The valley is a closed structural basin produced by faulting along 

the boundaries. The sedimentary beds in the mountains surrounding the 

valley have been folded and faulted. Extensive thrusting has occurred 

within the Flint Creek Range and several northeast-southwest trending 

67

Warm Springs State Hospital Project page 2 

anticlines and synclines are evident. Several faults within the 

mountains to the south and west are traceable into the valley, although \ 

direct evidence such as faultline scarps are lacking. The spring 

currently discharges water at 171°F, with a dissolved solid content \'^ 

of 1,250 mg/l. The source of the geothermal water is attributed to 

deep circulation In fault zones with a probable limestone matrix; 


The present drilling plan calls for drilling one production well 

to a depth of 1,250 +_ 250 feet. Disposal of the spent geothermal 

water will be utilized for the creation of a wetlands- for waterfowl, 

eliminating the need for an injection well. 

The engineering design will accomplish two well-defined tasks at 

Warm Springs, depending upon the well flow. 

1. Heating of domestic hot water; and 

2. Space heating of at least two buildings. 

Both heating tasks will be accomplished independently by using platetype 

counterflow heat exchangers, each task having its own exchanger. 

The domestic hot water heating requirements are estimated to be 100 

gal/min of 170°F geothermal fluid, with a AT of 60°F; the space heating 

requirements are estimated to be 200 gal/min at the same AT, 


Status: 

The geothermal demonstration plan includes drilling one production * 

well to a depth of approximately 1,250 feet. The expected production 

temperature is 170°F, at 300 gpm. The plan is to substitute geothermal 

energy for domestic hot water requirements and partial space heating 

of the Warm Springs facility, which is currently dependent upon natural 

gas. The water will be pumped through plate-type heat exchangers, 

with approximately 490 Btu per gallon of useful energy extracted in 

the process. The water will be discharged at 110°F into Montana 

Department of Fish, Wildlife, and Park's ponds adjacent to the hospital, 

for the creation of wetlands for migratory waterfowl. 

The Environmental Report has been prepared and reviewed by DOE. The 

geophysical survey conducted by the Montana College of Mineral Science 

consisted of gravity and resistivity surveys. The geophysical survey 

was supplemented by a review and interpretation of existing geologic 

and geophysical literature by Roger Stoker. The well site has been 

determined and well drilling is scheduled in September 1979. 

The legal review of state regulations for geothermal exploration and 

drilling has been completed. Applicable permits have been acquired. j 

MERDI is presently working with various state and federal agencies for 

the creation of waterfowl wetlands, using the disposed geothermal water. 

68 

"i. 

>

Group 10 

Appendix 1 

Industrial Process Heat Requirements at Temperatures 300*F (149*0) and BeloM 

Industry - SIC Group 

1. Copper Concentrate - 1021 

Drying 

Group 12 

2. Bituminous Coat - 1211 

Group 14 

Drying (Including lignite) 

3. Potash - 1474 

Drying FlIter Cake 

Group 20 - Food & Kindred Products 

4. Meat Packing - 2011 

Sausages and Prepared 

Meats - 2013 

Scalding, Carcass Wash and 

CIc.-nup 

Edible Rendering 

SnoklngAôoklng 

5. Poultry Dressing - 2016 

Scalding 

6. 

Natura! Cheese - 2022 

Pasteurization 

starter Vat 

Make Vat 

Finish Vat 

Whey Condensing 

Process Cheese Blending 

7. Condensed and Evaporated 

Milk - 2023 

Stabilization 

Evaporation 

SterlIIzation 

250* 

250* 

Appl IcaMon 

Temperature 

Requirement 

"F CC) 

( 121) 

150-250* ( 66-104) 

140 

200 

155 

( 121) 

( 60) 

( 93) 

( 68} 

140 ( 60) 

170 

135 

1C5 

100 

160-200 

165 

200-212 

160 

250 

( 77) 

( 57) 

( 41) 

( 3D) 

( 71-93) 

( 74) 

( 93-100) 

{ 71) 

(121) -• 

Process Heat 

Used for 

ApplIcation 

lo'^BTUAr 

do'^ KJAD 

4-76 

1.7 ( 1.6 ) 

18.0 (19.0 ) 

1.03 ( 1.09) 

43.7 

0,52 

1.16 

(46.1 ) 

( 0.S5) 

( 1.22) 

3.16 ( 3.33) 

1.28 

0.02 

0.47 

0.02 

10.2 

0.07 

2.93 

5.20 

0.54 

( 1.35) 

( 0.02) 

( 0.50) 

( 0.02) 

(10.8 ) 

( 0.07) 

( 3.09) 

( 5.48) 

( 0.57) 

Fluid Milk - 2026 

Pasteurization 162-170 ( 72-77) 1.44 ( 1.52)

Appendix 1 (continued) 

Industrial Process Heat Requirements at Temparatores 300"F (149*0) and Below 

(ndustry - SIC Group 

9, Canned Specialties - 2052 

Beans 

Precook (Blanch) 

Simmer Bfend 

Sauce Heating 

Processing 

10, Cannod Fruits and Vegetables 

2033 

Blanching/Peeling 

Pasteur I zstifw 

Br I no Syrup Heating 

Convnerc I a I Ster 111 zat Ion 

Sauce Concentration 

11. Dehydrated Fruits and 

Vegetables - 2034 

Fruit 4 Vegetable Drying 

Potatoes 

Peeling 

Precook 

Côk 

12. Frozen Fruits and Vegetables - 

2037 

Citrus Juice Concentration 

Juice Pasteurization 

Blanching 

Cooking 

13. Wet Corn Milling - 2046 

Starch Dryer 

Steepwater Heater 

Sugar Hydrolysis 

Sugar Evaporotar 

Sugar Dry or 

J4, Prepared Feeds - 2046 

Pellet Conditioning 

ApptIcation 

Tftmperature 

Requlretnent 

•F ' rc) 

180-212 ( 82-100) 

170-212 ' .( 77-100) 

190 t 88) 

250 t 121) 

iaO-212 

200 

200 

212-250 

212 

165-1SS 

212 

160 

212 

190 

200 

180-212 

170-212 

120* 

120 

270 

250 

120* 

160-190 

B2-100) 

93) 

93) 

I 300-121) 

( ;oo) 

{ 74-85) 

( 100) 

( 71) 

( 100) 

t 

( 

{ 

( 

68) 

93) 

B2-100) 

77-100) 

( 49) 

{ 49) 

{ 132) 

{ 121) 

( 49) 

t 82-B8) 

Prosess Hoat 

Used for 

ApplIcation 

lO'^BTUAr 

(10^2 i^j/YR) 

0.40 

0,24 

0.20 

0.36 

V.88 

0.15 

1.02 

1.67 

0.44 

4 -77 

[ 0.42) 

( 0.25) 

{ 0.21) 

( 0,40) 

( !,98) 

( 0.15) 

( 1,08) 

t 1,75) 

t 0.46) 

5.84 ( 6.16) 

0.35 

0.47 

0,47 

1.33 

0.27 

2.26 

1 .41 

3.03 

0.77 

1.89 

2.74 

0.16 

( 0.35) 

( 0.50) 

( 0.50) 

( 1.40) 

( 0,26) 

{ 2.38) 

( 1.49) 

( 3.20) 

( 0.81) 

[ 1.99) 

( 2.SS) 

( 0.17) 

2.28 ( 2.40) 

15. Broad and Baked Goods - 2051 

Proof 1ng 10.0 { 33) 0.84 { 0.69)

® 

16. 

17. 

18. 

19. 

20. 

21. 


industrial Process Heat Requirements at Temperatures 300'F (149*0 and Below 


Cane Sugar - 2062 

MIngler 

Me Iter 

Defecation 

Granulator 

Evaporator 

Beet Sugar - 2063 

Extraction 

Thin Juice Heating 

Thin Syrup Heating 

Evaporation 

Granulator 

Pulp Dryer 

Soybean 011 Mills - 2075 

Bean Drying 

Toaster Desolventizer 

Meal Dryer 

Evaporator 

Stripper 

Shortening i Cooking OII - 2079 

011 Heater 

Wash Water 

Dryer Preheat 

Cooking 011 Reheat 

Hydrogenation Preheat 

Malt Beverages - 2082 

Cooker 

Water Heater 

Mash T-jb 

Grain Dryer 

Brew Kettle 

Distilled Liquor - 2085 

Cooking (Whiskey) 

Cooking (Spirits) 

Evaporation 

Dryer (Grain) 

Distillation 

ApplIcation 

Temperature 

Requ 1rement 

•F 

CO 

125-165 

185-195 

160-185 

110-130 

265 

140-185 -- 

185 

212 

270-280* 

150-200 

230-200* 

160 

215 

300* 

225 

212 

160-180 

160-180 

200-270 

200 

300 • 

212 

180 

170 

300* 

212 

212 

320 

250-290* 

300 

230-250 

( 

( 

( 

( 

( 

52-74) 

85-91) 

71-85) 

43-54) 

129) 

( 60-85) 

( 85) 

( IOO) 

( 132-138) 

( 66-93) 

( 110-138) 

( 71) 

{ 102) 

( 149) 

( 107) 

( IOO) 

( 71-82) 

( 71-82) 

( 93-132) 

( 93) 

( li9) 

( 100) 

.( 82) 

( 77) 

( 149) 

( 100) 

( 100) 

( 160) 

( 121-143) 

( 149) 

( 110-121) 

Process Heat 

Used for 

Application 

lo'^BTUAr 

(10^2 K .lAR) 

0.59 

3.30 

0.44 

0.44 

26.39 

4.63 

3.08 

6.68 

30.8 

0.15 

16.5 

4.05 

6.08 

4.36 

1.62 

0.30 

0.72 

0.12 

0.60 

0.32 

0.37 

1.53 

0.53 

0.60 

9.18 

3.98 

3.16 

6.27 

2,32 

1.94 

7.69 

4-78 

( 0.62) 

( 3.48) 

( 0.46) 

( O.fr,) 

(27.84) 

( 4.88) 

( 3.25) 

( 7.05) 

(32.5 ) 

( 0.16) 

(17.4 ) 

( 

( 

( 

( 

( 

( 

( 

( 1.61) 

( 0.56) 

( 0.63) 

( 9.68) 

( 4.20) 

( 

( 

( 

( 

( 

4.27) 

6.41) 

( 4.60) 

( 1.71) 

( 0.32) 

0.76) 

0.13) 

0.63) 

0.34) 

0.J.9) 

3.33) 

6.61) 

2.45) 

2.05) 

6.11)

Appendix I (continued) 

Industrial Process Heat Requirements at Temperatures 300*F (149*C) and Below 


Application 

Temperature 

Requirement 

*F CO 

22. Soft Drinks - 2086 

Bulk Contulner Washing 170 ( 77) 

Returnable Bottle Washing 170 ( 77) 

Nonreturnable Bottle Harming 75-85 ( 24-29) 

Can Warming 75-35 ( 24-29) 

Group 21 - Tobacco 

23. Cigarettes - 2111 

Drying 

Rehumidification 

24. Tobacco Stemming & Redrying - 

2141 

Drying 

Group 22 - Textile Mill Products 

25. Finishing Plants, Cotton - 2261 

Washing 

Dye 1ng 

Drying 

26. Finishing Plants, Synthetic 

2262 

Washing 

Dyeing 

Drying & Heat Setting 

Group 24 - Lumber 

220* 

220* 

220* 

200 : 

200 

275 

200 

212 

275 

( 104) 

- - ( 104) 

( 104) 

• ( 100) 

( 100) 

( 135) 

( 93) 

( 100) 

( 135) 

Process Heat 

Used for 

Api*. i Ication 

lo'^BTUAr 

do'^ KJAR) 

0.21 

1.27 

0.43 

0.52 

0.43 

0,43 

0.50 

15.4 

4.5 

22.2 

35.9 

15.2 

23.2 

4-79 

( 0.22) 

( 1.34) 

( 0.45) 

( 0.55) 

( 0.45) 

( 0.45) 

( 0.26) 

(16.2 ) 

( 4.7 ) 

(23.4 ) 

(37.9 ) 

(24.5 ) 

27. Sawmills & Planing Mills - 

2421 

Kiln Drying of Lumber 200* ( 100) 63.4 (66.9 ) 

28. Plywood - 2435 

Plywood Drying 250 ( 121) 50.6 (53.4 ) 

29. Veneer - 2456 

Veneer Drying 212 ( 100) 57.8 (61.0 )


industrial Process Heat Requirements at Temperatures 300*F (149*C) and Below 

industry - SiC Group 

Group 25 - Furniture 

30. Wooden Furniture - 2511 

Makeup A'r & Ventilation 

Kiln Dryer & Drying Oven 

31. Upholstered Furniture - 2512 

Makeup Air & Ventilation 

Kiln Dryer & Drying Oven 

Group 26 - Paper 

32. Pulp Mills - 2611 

Paper Mills - 2621 

Paperboard Mills - 2631 

Bui I ding Fjper - 2661 

Pulp Refining 

Black Liquor Treatment 

Pulp i Paper Drying 

Group 28 - Chemical 

33. Cyclic Intermediates - 2865 

Styrene 

Phenol 

70 

150 

70 

150 

150 

280 

290 

34. Alumina - 28195 

Digesting, Drying, Heating 280 

ApplIcation 

Temperature 

Requirement 

•F CO 

250-300 

250 

35. Plastic Materials & Resins - 

2021 

Polystyrene, suspension process 

Polymerizer Preheat 200-215 

Heating Wash Water 190-200 

36. Synthetic Rubber - 2822 

Cold SQR Latex Crumb 

Bulk Storage 

Emulsification 

Blowdown Vessels 

Monomer Recovery by Flashl.-ig 

4 Stripping 

80-100 

80-100 

130-145 

120-140 

( 

( 

{ 

( 

21) 

66) 

21) 

66) 

( 66) 

( 138) 

( 143) 

( 121-149) 

( 121) 

( 138) 

( 93-102) 

( 88-93) 

( 

( 

( 

( 

27-38) 

27-38) 

54-63) 

49-60) 

Process Heat 

Used for 

Application 

lo'^BTUAr 

(I0'2 KJAR) 

5.7 

3.8 

175 

164 

383 

1.4 

0.9 

35.0 

0.45 

113.2 

0.102 

0.067 

0.179 

. 0.086 

0.665 

4.095 

(continued on 

4-80 

( 6.0 ) 

( 4.0 ) 

( 1.5 ) 

( 0.9 ) 

(185) 

C173) 

(404) 

(37.0 ) 

( 0.47) 

(119.4 ) 

(0.107) 

(0.068) 

(0.189) 

(0.091) 

(0.912) 

(4.319) 

next page)


industrial Process Heat Requirements at Temperatures 300*F (149*C) and Below 

industry - SIC Group 

36. Synthetic Rubber - 2822 (contli lued) 

Dryer Air Temperature 

Cold SBR, Oli-Carbon Black 

Masterbatch 


OII Emulsion Holding Tank 

Cold SDR, Oii Masterbatch 


Oil Emulsion Holding Tank 

37. Celluloslc Man-made Fibers - 

2823 

Acrylic 

38. Noncellulosic Fibers - 2824 

Rayon 

Acetate 

39. Pharmaceutical Preparations - 

2834 

Autoclaving & Cleanup 

Tablet ft Dry-Capsule Drying 

Wot Capsule Formation 

40. Soaps & Detergents - 2841 

Soaps 

Various Processes In Soap 

Manufacture 

Detergents 

Various Low-Temperature 

Processes 

41. Organic Chemicals, N.E.O. - 

2869 

Ethanol 

isopropanol 

Cumene 

Vinyl Chloride Monomer 

Appli cation 

Temperature 

Requi rement 

•F 

(*C) 

150-200 

150-200 

80-100 

150-200 

60-100- 

( ^ 


Industrial Process Heat Requirements at Temperatures 300*F (149°C) and Below 


43. Explosives - 2892 

Dope (Inert Ingredients) 

Drying 

Wax Melting 

Nitric Acid Concentrator 

Sulfuric Acid Concentrator 

Nitric Add Plant 

Blasting Cap Manufacture 

Group 29 • PeTroleum 

44. Petroleum Reglning - 2911 

Alkylation 

Buta-iicne 

300 

200 

250 

200 

200 

200 

ApplIcation 

Ter:i9rature 

Requirement 

•F CC) 

( 149) 

( 93) 

( 121) 

( 93) 

( 93) 

( 93) 

45-300 ( 7-149) 

250-300 ( 121-149) 

Process Heat 

Used for 

ApplIcation 

lo'^BTUAr 

(10^^ KJAR) 

0.006 

0.118 

0.070 

0.027 

0.223 

0.016 

59 

60 

-82 

{ 0.006) 

( 0.12 ) 

( 0.07 ) 

{ 0.02 ) 

( 0.23 ) 

( 0.01 ) 

45. Paving Mixtures - 2951 

Aggregate Drying 275-300* ( 135-149) 88.1 (92.9 ) 

Group 30 - Rubber 

46. Tires 4 Inner Tubes - 3011 

Vulcanization 250-300 ( 121-149) 6.16 ( 6.52) 

Group 31 - Leather 

47. Len-rher Tanning 4 Finishing - 

3111 

Beting 

Chrome Tanning 

Retan, Dyeing, Kjt Liquor 

Wash 

Drying 

Finish Drying 

90 

85-130 

120-140 

120 

no* 

no* 

Group 32 - Stone, Clay, Glass t Concrete Products 

32) 

29-54) 

49-60) 

49) 

43) 

43) 

0.094 

0.060 

0.15 

0.034 

2.05 

0.13 

(62) 

(63) 

( 0.099) 

( 0.063) 

( 0.16 ) 

( 0.036) 

( 2.16 ) 

( 0.14 ) 

48. Hydraulic Cement - 3241 

Drying 275-300* ( 135-149) 6.0 ( 6.0 ) 

49. Concrete Block - 3271 

Ejj.-a Low-Pressure Curing 165* ( 74) 12.29 (12.96)

^ 


Industrial Process Heat Requlrcrents at Temperatures 300*F (I49*C) and Below 

industry - SiC Group 

50. Ready-Mix Concrete - 3273 

Hot Wr.ter for Mixing Concrete 

51. Gypsum - 3275 

Wo 11 board Dry Ing 

52. Treated Minerals - 3295 

KaoI in 

Drying 

Expanded PerlIte 

Dr yIng 

Barium 

Drying 

Group 33 - Primary Metals 

53. Ferrous Castings 

Gray Iron Foundries - 3321 

Mat ieable Iron Foundries - 3322 

Steel Foundries - 3323 

Pickling 

Group 34 - Fabricated Metal Products 

54. Galvanizing - 3'.79 

Cleaning, PIcklIng 

Group 36 - Electrical Machinery 

55. ftotor 4 Generators - 3621 

Drying 4 Preheat 

Baking 

Group 37 - Transportation Equipment 

ApplIcation 

Temperature 

Requirement 

•F CC) 

120-190 ( 49-138) 

300 ( 149) 

230* 

160* 

230* 

( 110) 

( 71) 

( 110) 

100-212 ( 38-100) 

130-190 ( 54-8(J) 

150 

300 

( 66) 

( 149) 

Process Heat 

Used for 

ApplIcation 

lO'^TUAr 

(10^^ KJAR) 

4-83 

0.34 I 0.36) 

11.18 (11.79) 

12.7 (13.4 ) 

0.22 ( 0.23) 

0.34 ( 0.36) 

151 (160) 

0.011 ( 0.012) 

0.043 ( 0.045) 

0.133 ( 0.140) 

56. Motor Vehicles - 3711 

Baking-Prime 4 Paint Ovens 250-300 ( 121-149) 0.29 ( 0.31 ) 

Note: SIC Groups 34, 35, 36, 37 utilize tiot water for parts degreasing and washing In 

application temperatures of BO-IBO-F (27-82°C); total process heat used is not currently 

aval table. 

*No special temperature required; requlromont is simply to evaporate water or to r''y tho 

material.

FEDERAL ASSISTANCE PROGRAM 

PROJECT STATUS REPORT 

GEOTHERMAL TECHNOLOGY TRANSFER 

GRANT NO, DE-FG-07,-83ID 12478 MOll 

Reporting Period: June 1987 

PAUL J, LIENAU AND GENE CULVER 

Geo-Heat Center 

Opegon Institute of Technology 

Klamath Falls, Oregon 97601

1. PROJECT SUMMARY - JUNE 1987 

1.1 Geothermal Information Services. Advising was provided to 13 inquiries 

and materials were sent to 23 requests, 6 hours of lectures and a 

tour of geothermal sites in the Klamath Falls area were presented to an 

Elderhostel at OIT, and one additional tour was given . 

1.2 Geothermal Progress Monitor. Progress monitor activities are 

reported on: 1) New developments at Susanville, CA; 2) Binary power plant 

to be built at Amedee, CA; 3) Carson City, NV elementary school to use 

geothermal; and 4) Decision reached for test drilling near Crater Lake, OR. 

1.3 Geothermal Direct Heat Applications Handbook. Draft status of 

work on chapters is indicated and delivery dates are given. 

1.4 Geothermal Technology Support to End-Users reported under 

advising for June. 

1.5 Geo-Heat Center staff that worked on the project in June include: 

Paul Lienau il%). Gene Culver (72%), Cindy Nellipowitz (49X), Joyce Pryor 

(17%), Kevin Rafferty (84%), Charles Higbee (66%), and our student library 

assistant worked 27 hours. 

2. GEOTHERMAL INFORMATION SERVICES 

Transfer of technical Information on geothermal resources and 

applications is provided to potential users, consulting engineers, industry 

groups, developers and the general public. This effort includes advising, 

distribution of published material, publishing a Quarterly Bulletin, maintaining 

a geothermal technology library, presentations and tours, and 

issuing geothermal technology development status reports for the Progress 

Monitor. 

2.1 Advising. The following phone and letter inquiries, and personal 

visits were handled by the GHC during June 1987. 

Name Date Nature 

a. Jack McNamara 6/1 Resource. Requested information on Raft 

11752 San Vicento Bvd. River resources for direct use applications. 

Los Angeles, CA ' Previous studies on direct uses for irri-. 

gation, fish farming, potato dehydration and 

soil warming were sent.

. 

c. 

d. 


Darrel Seven 

D No. 7 Ranch 

Sunmer Lake, OR 

Tom Drougas 6/10 

Guyer Springs Water Go. 

Ketchum, ID 

Alex Sifford 

Oiêgon DOE 

Salem, OR 

Leo GTinkmah 

6th St. Steel 

Klamath Falls. OR 

Sandy Baisiger 

Caldwell Bankers 

Klamath Falls, OR 

Rick; Chitwood 

Chitwood Energy 

Mt. Shasta, CA 

Mgt. 

Glen Townsend 

Ft. Bidwell Tribal 

Fort Bidwell, CA 

6/8 Well Testing, Owns three wells, one producing 

1000 gpm, and the other two at 200- 

300 gpm with an average temperature of 230''F. 

provided referral to three pumping contractors 

in the Klamath area th^t can perform 

a pump test. Interested tn bottling 

mineral water. 

Space Heating. Planning to provide geothermal 

for space heating of condominiums. 

Requested an economic analysis computer 

run on the project using RELCOST. A form 

for input data was senti 

6/10 Well Test. Requested cost of well test conduc;ted 

at the Klamath College Industrial 

Park. The cost for a six day pump test was 

$8,250 excluding MOB and de-MOB and monitoring 

observation welTs. 

6/15 Equipment. Requested heat transfer rates 

from finned pipe for use in the Lakeview 

greenhouse. Calculated values were provided 

for given temperatures and pipe dimensions. 

6/16 Wells. Provided data on two wells located 

in the Klamath Falls urban area. 

6/18 Space Heating. Requested information on 

Cedarville Hospital and Fort Bidwell 

feasibility studies. Especially neetied data 

for heat exchangers (copper coils and H2S 

reaction) and alternative pipe materials. 

He wanted to know how, to sample for H25, 

Provided materials selection guide, sampling 

techniques and information on corrosion in 

low temperature geothermal. 

6/19 Space Heating. Requested .names of ex- 

Council perienced' geothermal contractors to install 

system for home heating regarding feasibility 

study completed by the GHC last year. 

Names and phone numbers of five contractors 

were supplied..

1. 

k. 

1. 

m. 


Gib Cooper 

Mendocino Jr. 

Lakeport, CA 

Ray Rangila 

Confederate Tribes 

Warm Springs 

Warm Springs, OR 

Klaus Findler 

Wheatley, NY 

Darrel Seven 

Paisley, OR 

John Hader 

1108 W. Jon St. 

Pasco, WA 

6/23 Greenhouses. Requested a review of plans 

College for experimental geothermal greenhouse. 

6/25 Space Heating. Requested feasibility study 

of for heating lodge, which is i mile from 

the springs. 

6/30 Power Generation. Requested names of U.S. 

manufacturers of modular binary power plants. 

Provided ORMAT and Barber-Nichols 

Engineering. 

6/30 Swimming Pool. Planning to build RV park 

with hot tubs and swimming pool. Discharge 

temperature from the facility is estimated 

at lOS'F. Disposal is by means of discharge 

into sewage ponds. Bacterial will not function 

above BO'F, with ideal temperatures between 

60 to 65"F. 

6/30 Greenhouses. Requested information on 

heating geothermal greenhouses with a 120''F 

hot spring at Lolo Pass, ID. Provided greenhouse 

heating guide. 

2.2 Information Materials. The following requests were received by the 

Geo-Heat Center for published materials. 


Sally Benson 6/1 

LBL 

Berkeley, CA 

b. Mike Wright 

UURI, Earth Sci. Lab 

Salt Lake City, UT 

c. Joe Kanta 6/1 

Caldwell, ID 

Letter requesting review of draft handbook 

chapter on DHE's. 

6/1 Copy of same. 

Letter, feasibility study on Moana, papers 

on Eval & Design of DHE's, Natural Convection 

Promoter for Geo Wells and draft copy of DHE 

chapter for handbook.


d. Jack McNamara 6/2 

Los Angeles, CA 

e. Alex Sifford 

ODOE 

Salem, OR 

f. Jozef Csaba 6/4 

2443 Szazhalombatta 

Pf 32 

HUNGARY 

g. S.S, Kittur 6/8 

Mgr. Planning 

Thermax Private Ltd. 

Thermax House 

4 Bombay Pune Rd 

Shivajihagar Pune 411005 

INDIA 

h. Robert Cherry 6/9 

Vice Pres., Engineering 

Layne S Bowler Inc. 

Memphis, TN 

i. Gharles Sundquist, PE 6/11 

Richland,, WA 

Gordon Bloomquist 6/11 

WSEO 

Olympia., WA 

Ben Lunis 

EG&G Idaho 

Idaho Fails. ID 

Tom Orougas 6/15 

Guyer Spgs Water Go. 

Ketchum, ID 

Letter regarding request for information on 

Raft River. Enclosed 4 technical publications 

on loan from GHC library^ 

6/3 Copy of map from Oregon Site Data Base book. 

Information on geothermal in HI, greenhouse 

heati g, copy of draft chapter on greenhouses 

for handbook, back bulletin on greenhouses. 

Letter, Publication Request Form, information 

on geothermal In India, refei^ral to Geol. 

Survey of India for more information. 

Letter regarding bearing failure at MWMC in 

Klamath Falls, OR (hospital). Enclosed 

slides and piece of bearing. 

Letter regarding his. proposed absorption 

power generator. Suggested he write ah 

article for the Bulletin. Enclosed back 

issues of the Bulletin. 

Letter regarding GHC's providing data to 

WSEO on DH systems in Klamath. Falls area if 

WSEO's proposal for GEODIM is approved. 

6/11 Copy of same. 

Letter, form to fill out for RELCOST life 

cycle analysis.


m. Kevin Fisher 6/15 

City Water Dept, 

San Bernardino, CA 

n. C. McGuire 6/17 

Centrilift Hughes 

Huntington Beach, GA 

0. Jack Frost, Mgr, 6/17 

Geo. Services Div. 

Azusa, CA 

p, Alex Sifford 6/18 

ODOE 

Saiem, OR 

q. Rick Chitwood 6/18 

Chitwood Energy Mgt. 

Mt. Shasta, GA 

r. R.C. Cherry 6/18 

Layne & Bowler Inc. 

Memphis, TN 

s. David Bomar 6/22 

Balzhiser, Hubbard & Assoc. 

Eugene, OR 

t. Cecil Kindle 6/22 

Battelle NW 

Richland-, WA 

u. Bob Helm 6/25 

,PP&L, Columbia Div. 

Portland, OR 

B.J. Pfeffer 6/25 

Calgary, Alberta 

CANADA 

w, George Wagner 6/16 

JUB Engineering 

Boise, ID 

Letter with slides of San Bernardino geothermal 

system. 

Letter requesting review of draft chapter on 

pumps for handbook. 

Letter requesting review of draft chapter on 

puitips for handbook. 

Letter, enclosed slides of Oregon Trail 

Mushroom plant. 

Copy of techniques for geothermal liquid 

sampling and analysis. 

Letter, draft chapter on pumps for handbook 

for hisi review. 

Letter, copy of draft chapter on pumps for 

handbooks for his review. 

Letter, copy of dra.ft chapter for handbook 

taken primarily from Battelle pubTication.. 

Asked for permission and review. 

Letter explaining occupancy schedule used 

to determine heat load in study of Convention 

Center. Enclosed Publication Request Fbrm 

and back Bulletin. 

General information on GHC,: back Bulletins, 

Publfcation Request Form. 

Letter with enclosures on piping and 

general geothermal.

2.3 Presentations and Tours. 

2.3.1 Paul Lienau presented three lectures to 25 persons attended Elderhostel 

at OIT and provided a tour of Klamath geothermal sites. 

2.3.2 A presentation was requested by the City of Klamath Falls to the 

Oregon Utilities Coord. Council for 21 Aug. 1987. 

2.3.3 A tour and talk on Klamath geothermal sites was requested for 40 

persons from Rogue Valley for September. 

2.3.4 Gene Culver provided a tour for four people from Tigard, OR of 

the geothermal system at OIT on June 22nd. 

3. GEOTHERMAL PROGRESS MONITOR 

4. 

4.1 

book" is 

Chapter 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

attached 

GEOTHERMAL DIRECT HEAT APPLICATIONS HANDBOOK 

Status of work on the "Geothermal Direct 

as follows: 

Introduction & State of the Art 

Program Opportunities Notice (PON) 

Lessons Learned 

Nature & Distribution of Geothermal 

Exploration for Geothermal Resources 

Water Sampling Techniques 

Drilling & Well Construction 

Well Testing 

Materials Selection 

Well Pumps 

Piping 

Heat Exchangers 

Space Heating Equipment 

Heat Pumps 

Absorption Refrigeration 

Greenhouses 

Aquaculture 

Industrial Applications 

Engineering Cost Analyses 

Institutional, Legal & Permit Requi 

by State 

Environmental Aspects 

Heat Applicatior is Hand- 

Project 

Resources 

rements 

Status . 

Not Started 

In Progress 

In Progress 

In Progress 

Completed 

In Progress 

In Progress 

Completed 

Completed 

In Progress 

Completed 

In Progress 

Not Started 

Completed 

Completed 

Completed 

Not Started 

In Progress 

In Progress 

In Progress

3. GEOTHERMAL PROGRESS MOMITOR 

3.1 New Developments in Susanville. Two additional 

facilities will be connected to the Susanville geothermal 

district heating system and a new injection well will be 

drilled. 

The SHsanville California geothermal districit heating 

system is designed to provide space heating to two separate 

geothermal loops. The first loop, in operatiron since 1982, 

circulates 170 F fluid to nineteeri public and commercial 

buildings, and a second to 23 homes. 

Two additional facilities will be connected to the 

system by Oct. 1, 1987. The Roosevelt swimming pool will, be 

connected to enable year around use. Geothermal will be used 

for space and pool heating. City shops will also be 

retrofitted to utilize geothermal for space heating from the 

district system, 

Susanville has had difficulty finding a suitable 

disposal method for the geothermal effluent from the system. 

Originally/ a well drilled by the Bureau of Reclamation, 

Richardson 1, Was to be used. The Richardson well had a poor 

injectivity, 0.85 gpm/foot, which is dhly 1/10 the 

productivity of other wells in the area, and a high skin 

factor which indicated the well was damaged during drilling 

by mud invasion into permeable zones. This well was able to 

accept only 150 gpm of an estimated, average 400 gpm required 

by the system. Temporary suface discharge permits had tp be 

obtained from the State Department of Water REsources, which 

considers geothermal water to be a hazardous waste. To 

resolve this prbbleiin, the city has obtained funds from the 

California Energy Commission and HUD to drill a hew 500 ft. 

injection well between SU2y's 5 and 7 production wells and 

near the Tsuji nursery. This well is expected to accept 500 

gpm and about 600 ft. of pipeline will be re.guired to connect 

to the existirig system. 

3.2 Binary Power Plant to be Built at amedee. Amedee hot 

springs is located .near Wendel and has been a site where 

several successful wells have been drilled. Transpacific 

Geothermal Corporation has received permits to build the 

Amedee Geothermal Power Plant Project... The 1,5 MW plant will 

utilize two existing wells, Norcal No. 1 and No. 2, to 

provide 3800 gpm bf fluid at 226°F to the.plant. A 20 year 

contract has been sighed with PG&E and CP National's 

transmiss.ion lines wall be used to tie into the grid. 

7a'

3.3 Carson City Elementary School to Use Geothermal. The 

Stanton Drive Elementary School of the Carson City School 

District will be heated by geothermal resources and will be a 

state energy pilot project. Design Concepts West of Carson 

City, Nevada, selected as the architect to design several new 

facilities for the district, has commenced the design of the 

Stanton Drive Elementary School. 

3.4 Decision Reached for Test Drilling near Crater Lake. 

The Bureau of Land Management (BLM), Lakeview District, and 

the United States Forest Service (USES), Winema National 

Forest, have reached a decision on a request to deepen 

temperature gradient wells and drill without circulation on 

the Winema National Forest by California Energy Company, Inc. 

The decision is to implement the proposed action, to drill on 

previously disturbed sites within the unitized areas to 5,500 

feet and with fluid loss to the subsurface. The reasons 

given were: 

a. A detailed computer model analysis of the possible 

impacts of fluid loss from drill holes in the vicinity 

of Crater Lake indicates that this fluid loss could pose 

no threat to Crater Lake or affect the hydrologic system 

in the immediate vicinity of the lake caldera. 

b. Subsurface aquifers are adequately protected by the 

requirements to seal zones of inflow and to use 

non-toxic drilling fluids. 

c. Surface related impacts are considered negligible. 

d. With the exception of drilling .depth and fluid loss, 

the special design features and mitigation measures 

developed in the original 1984 EA and the monitoring 

plan requirements remain unchanged. 

e. BLI-I and USES will conduct detailed on-site 

inspections for each proposed site location prior to any 

surface disturbance. Personnel from the NFS will be 

invited to attend this inspection. 

f. Drilling to 5,500 feet will provide data that will 

improve the understanding of the hydrology and geology 

of the Crater Lake area. This information should prove 

useful for future decisions related to geothermal 

exploration and provide information to the National Park 

Service and the Forest Service to aid them in their 

management efforts. 

7b

g. If a new or amended Geothermal Drilling Permit 

Application is received from California Energy Company, 

Inc., the decision on the application will be based on 

the original and supplemental EAs and any newly 

generated information. 

This decision will be implemented after a 30-day period has 

elapsed to allow for any appeal. 

7c

4.2 Schedule of Delivery Dates: 

4.2.1 August 1, 1987 - Chapters to peers for review. Each author to 

choose peersi 

4.2.2 September I, 1987 - Chapters returned from peer review to allow 

time for updates and changes. 

4.2.3 October 1, 1987 - Edit peer reviewed proof by Paul Lieriau & Ben 

Lunis, 

4.2.4 December 1987 - Printer ready. 

5, GEOTHERMAL TECHNOLOGY SUPPORT TO END USERS 

Technical assistance for June is reported under 2.1, Advising,

Figure I Generalized map of the Wilbur Mining ... - University of Utah

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