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law.
A Decade of Geothermal
Development in the United States
7974 - 7984: A Federal Perspective
- Part I -
1974 was a banner year f o r geothermal energy in the
United States. Three events of ma.jor significance took
place that in 1984 provided t h e baseline for measuring
progress in the dewlopment of this resource.
T h e Geothermal Energy Research. Development,
a n d Demonstration Act ( R I X D ) was enacted by the U.S.
Congress o n 3 September 1974, establishing a formal
federal geothermal research a n d development program.
In August of that year, the first competitive geothermal
leases were issued pursuant t o the Geothermal Steam Act
of 1970. And in t h e s a m e year. t h e U . S . Geological Survey
initiated the first comprehensive assessment of t h e geothermal resources of the United States.
These actions did not result in a n oversight success
stor!'. To t h e c o n t r a r y , progress has been slow over t h e I O
)'ears in both technology development a n d leasing of the
federal lands available for geothermal exploitation, the
pace retarded by many direct a n d indirect influences. In
addition, a large portion of t h e Nation's resource base has
yet to be identified. Nevertheless, in 1984 real progress
arrived in geothermal development, a product of the
efforts of industry a n d government.
Geothermal Research, Development
and Demonstration Act
In 1974. memories of t h e long lines of gasoline serLice stations, created by t h e 1973 e m b a r g o o n shipments
o f foreign oil, were very fresh in t h e minds o f t h e
American public. Prices of energy in all forms were soaring. As a result, public pressure f o r federal s u p p o r t of t h e
development of alternative f o r m s of energy grew t o a
ground swell. I t was in this climate that t h e Geothermal
KD&D Act was passed.
Page 10
T h e Atomic Energy Commission had been 0'
riven a n
earlier mandate from Congress to conduct geothermal
research a n d development. a s had t h e National Science
F o u n d a t i o n . While s o m e o f t h e major geothermal programs still ongoing t o d a y had their origins within those
agencies, the RD&D Act made t h e first "national c o m mitment .._t o dedicate t h e necessary financial resources
a n d enlist the cooperation of t h e private a n d public
sectors in developing geothermal resources ..."
Responsibility for coordinating a n d managing the
federal geothermal R&D program was placed in a Geot her m a I E ne rg y Coo rd i nation a n d M a n a g e men t Pr ojec t ,
known t o d a y a s t h e Interagency Geothermal Coordinating Council. However, when t h e Energy Research a n d
Development Administration ( E l i D A ) was created in
J a n u a r y 1975, it was given responsibility f o r the federal
R & D p r o g r a m . T h e responsibility w a s subsequently
passed to t h e Depatment o f Energy ( D O E ) when it was
created in 1977.
The Geothermal "Industry" in 1974
I f the term "industry" is defined here a s a g r o u p of
for-profit enterprises, the geothermal industry in 1974
consisted of
t h e power generating plants a t T h e Geysers a n d
t h e wellfield providing steam
t h e Boise, I d a h o , district heating system
a few small commercial greenhouses
their suppliers of energineering serviczj, eyuipment, a n d materials.
T h e only o t h e r uses of record were o t h e r direct heat
applications by both t h e public a n d private sectors.
The generating capacity a t T h e Geysers
Ten Pacific Gas a n d Electric Co. ( P G & E ) units were
on-line. a n d the operation was second in si7e only t o the
geothermal installations a t Larderello, Italy. Six modern
50 MWc plants accounted for the bulk of the capacity, a
giant step from the first 1 1 MWc plant build in 1960.
C o n t r a r y t o the ascendancy of T h e Geysers operations, the oldest geothermal district heating system in this
country was in decline. At its peak, the Warm Springs
Avenue system in Boise, Idaho, served 400 homes a n d
business establishments. By 1974, thedistribution system,
built in 1890, had become antiquated, badly in need of a
ma.jor capital outlay for renovation, a n d only marginally
Geothermal Resources Council BULLETIN lune 1986
profitable for the Boise Water System. A citiyens group,
independently incorporated a n d privately financed. had
takcn over t h e operation to serve the remaining 170
c 11s t 0 niers.
Hy 1974, most o f t h e eastern portion of t h e City of
Klamath t-'alls, O r e g o n , was heated by hot water in a
unique application that is. t o a large extent, a one-wellone-structure approach, with approximately 400 wells
supplying a b o u t 500 structures in 1974. Since a t least the
turn o f the centur!', users had installed their own wells,
typically using a downhole heat exchanger t o heat city
water circulating in a closed system. S p a c e heat users in
1974 includcd residences, city schools, a n d the Oregon
Institute of Technology. O t h e r users included milk
pasteruriyaion a n d commercial laundering.
f o r growing tomatoes by the soilless hydroponic method.
T h e hot water f r o m a surface hot spring
n o wells were
drilled
was used t o heat t h e greenhouses a n d , with the
addition of nutrients, to irrigate the plants which were
grown in gravel. By mid 1974, six greenhouses had been
completed in this facility.
~
The Geothermal Industry in 1984
Despite several factors working against it. a geothermal industry is emerging t o d a y beyond the realm of
T h e Geysers. T h e hot water resource has reached commercial status notwithstanding: 1 ) reduced power plant
construction of all types; 2) low competing fuel prices; 3)
very high geothermal drilling costs; a n d 4 ) relatively new
power conversion technologies.
T h e total megawatt capacity of all t h e hot water
plants in operation. under construction, and planned in
the U . S . is only a fraction of that of the established fossil
a n d nuclear power industries. Nevertheless, the number of
plants is significant in today's market of lower than
expected power d e m a n d , a n d their sire is a plus factor in
satisfying today's smaller increments of growth. They will
also provide t h e experience needed t o attract others t o the
use of this resource.
I k v e l o p m e n t a l s o continues a t T h e Geysers, by newcomers a s well a s the established steam producers and
utility. 'l'his area embraces the greatest a m o u n t of geothermal power generation capacity o f a n y site in the world
despite some large deLelopincnts a b r o a d .
A number of new direct uses ofgeothermal heat have
been installed, beyond a g r o u p of such projects partially
f u n d e d by DOE a s field experiments.
Hydrothermal Power Generation
Pacific Gas and Electric Unit No 1 at The Geysers the first
c o m m e r c i a l power plant in the U S (Courtesy of Pacific Gas and
Eiectiic Company)
At this time, the Bureau of Reclamation was operating a demonstration o f desalting geothermal brines at East
Mesa i n t h e Imperial Valley t o study the feasibility o f
augmenting the water supply t o the Colorado River from
sotirce,s u.ithin the Basin. I t was determined, however. that
all desalting processes tried were far t o o expensive, including a multistage llash desalting plant combined with a
binary power plant for the concurrent production of water
a n d power.
Perhaps the best known geothermal greenhouses in
the inid 1970s were those near Susanville, California, used
Geothermal Resources Council BULLETIN June 1986
As indicated by the a b o v e discussion. the geothermal
industry today is confined t o the use of H I ~ l r o t h r r t i i u l
fluids, a n d , except f o r a small, pilot-scale geothermal
generating unit in Hawaii a n d a n o t h e r operated briefly in
Idaho, California was the scene of all U . S . geothermal
power development until 1984. T o d a y , there a r e plants,
some o f t h e m small-scale units, operating in N e w d a , New
Mexico, and Utah. Additional geothermal capacity is
planned for these three states a n d Oregon.
California will remain t h e leader f o r t h e foreseeable
future, however. This is true even when t h e capacities of
plants under construction o r planned to utiliye liquiddominated resources a r e tabulated alone, uninflated by
the large capacity a t T h e Geysers.
At this writing, contracts a r c in place for the purchase
of the power output of a b o u t 250 M We from nine "hot
water"p1ants in California existing o r under construction.
Approximately 80 percent of this capacity is in Imperial
Valley. Expansion is planned for several of the plants
e.g., the capacity of the China Lake Naval Weapons Center facility is t o be increased in increments from the initial
25 M We currently under construction.
Page 11
1974 geothermal greenhouse in Raft River Valley, Idaho.
The heat exchanger (shown here) was a tub of hot geothermal water
In addition t o t h e “boost” given to geothermal
development by the new plant construction, considerable
encouragement for the future of this resource is offered by
t h e performance of t h e existing hot water demonstration
plants. While both t h e M a g m a Power Co. 10 MWe binary
plant at East Mesa a n d t h e Union Oil Co. of California
Southern California Edison (UNOCAL)/(SCE) flash
plant of the same size at Brawley suffered some initial
difficulties after they came on-line in 1980, t h e performa n c e of t h e binary plant is now reliable a n d consistent.
Similarly, although all problems a r e not completely
solved. the U N O C A L /SCE 10 MWc plant near the Salton
Sea, which began operation in 1982, is performing well. In
addition, the Utah Power a n d Light Co. was sufficiently
impressed with t h e efficiency of a small (1.6 MWe)
Riphase generating unit subjected t o long-term performance tests that it is using this total flow technology to
increase the o u t p u t of both its 20 M We plant near Milford
a n d t h e new 14 M We plant under construction (Figure I ) .
More information o n t h e individual hot water plants
under construction a n d planned is included below.
T h e scene a t T h e Geysers has changed markedly since
1974. PG&E’s generating capacity has increased f r o m less
than 400 MWe to over I100 MWe, a n d the number of
plants has grown from 10 to 17. A n additional 262 M We is
generated by newcomers t o T h e Geysers. Owners of these
include the Northern California Power Agency ( N C P A ) ,
Sacramento Municipal Utility District ( S M U D ) , a n d
S a n t a F e International. T h e S a n t a F e plant. built by
Page 12
(180’F)
Occidental Geothermal, is t h e first a t T h e Geysers to be
owned by a non-utility field developer.
Occidental was only o n e of several new field developers operating in the area. Once the sole domain of the
U n i o n ) M a g m a , Thermal consortium t h a t originally supplied all of PG&E’s suppliers now include UNOCAL..
Thermal Power Co., Geysers Geothermal, M C R Geothermal a n d Geothermal Resources International.
T h e plants scheduled t o come on-line in I985 included
the Bottle Rock plant of the California Department of
Water Resources, the second N C P A plant a n d PG&E’s
Units 16 a n d 20.
I..
I
.
&phaseu
turbine \
- -
/
$
Separared
steam
7 Electric
b
i
n
Sreem
e
genere for
from w e / /
Two phese
nozzle
Concenrrared
high pressure
brrne reinjection
into well
Clean
werer
F i g u r e 1 The BiPhase rotary-separator turbine converts kinetic
and pressure energy in the geothermal brine to shaft power It IS a
valuable adjunct to flash steam turbine installations
Geothermal Resources Council BULLETIN lune 1986
At 135 MWe. this Pacific Gas and Electric plant at The Geysers
IS
the largest geothermal power plant in the world
Large m o d e r n geothermal greenhouse at Bluffdale, Utah The entire geothermal system, including
production and injection wells cost less than one year's natural gas requirement Operation and maintenance
costs are minimal (Courtesy of Utah R o s e s )
Geothermal Resources Council BULLETIN June 1986
Page 13
Direct Use
T h e a n n u a l thermal energy use of a total of over 260
geothermal direct use projects, either on-line o r under
construction, has been estimated to be over I861 billion
Btu’s. A recent survey by the Meridian Corporation found
that of the total a n n u a l direct utilization, space a n d water
conditioning projects (473 billion Btu) account f o r
approximately 25 percent: district heating projects (426
billion Btu) a r e estimated t o account f o r 23 percent;
commercial fish farms (396 billion Btu) comprise 2 1
percent; commercial greenhouses (328 billion Btu)
contributed 18 percent: while projects involving small
resorts (120 billion Btu) a n d industrial process heat ( 1 I8
billion Btu) combine t o make u p the remainder. All but
o n e of t h e identified active projects a r e located in states
west of the Mississippi River, with the bulk of the geothermal energy direct heat utilization occurring in California, Idaho, Oregon, Nevada, a n d New Mexico.
Under the narrow difinition of a “district heating
system” used in t h e survey - a public utility system
there a r e eleven such systems in operation in the U.S. a n d
six u n d e r c o n s t r u c t i o n . O t h e r m u l t i p l e - s t r u c t u r e
geothermal heating systems, such a s those of college
campuses, o t h e r institutions, a n d large resort complexes,
were counted in the “space a n d water conditioning
projects,” the largest of the utilization categories.
Of the nine aquaculture pro.jects identified, three
large fish farms in Buhl, Idaho; Wabuska, Nevada; a n d
Mecca, California, account f o r nearly 80 percent of the
tot a I en erg y i‘o ns u m pt i o n . -I-we n t y -e i g h t c o m me rc ia 1 ge othermally-heated greenhouses a r e in operation, many
with very attractive payback periods. Products produced
include decorative flowers, potted plants, a n d hydroponically grown vegetables.
Geothermal heat for industrial processing, although
potentially very attractive, is used a t only a handful of
locations in the U.S. d u e t o some extent t o difficulties in
relocating a commercial enterprise t o a geothermal site.
The total estimated value f o r direct heat geothermal
u t i l i n t i o n through industrial processing was derived from
a sewage digestion plant in S a n Bernardino, California, a
vegetable drying facility a t Brady Hot Springs, Nevada,
a n d copper processingat Hurley, New Mexico. T h e mushroom growing facility a t Vale, Oregon, was considered as a
greenhouse.
T h e future growth of direct use applications have
been impacted by t h e expiration of b o t h the residential
a n d business energy t a x credits a t the end of 1985. T h e
maximum credit f o r residential was 40 percent of the first
$10,000 of expenditures, or $4,000, a n d the business credit
is 15 percent.
Contributions to the Emergence of the
“Hot Water” Industry
How has a n industry t o utilize liquid-dominated geothermal reservoirs for power generation a n d direct use
applications emerged in spite of all of the technological
a n d instutional barriers of its development‘? It has resulted
Page 14
from the interactingcontrihutions o f a number of forces a t
work t o make it happen:
the interest a n d perserverance of many individuals
a n d companies in the private sector
the industry-guided R&D a n d commercializition
programs of D O E a n d its predecessors
the U.S. Geological Survey assessments of the s i x
a n d locations of the Nation’s geothermal resource
base
t h e efforts of t h e Departments of t h e Interior a n d
Agriculture t o overcome the obstacles to gcothermal leasing a n d permitting o n federal lands
more favorable federal t a x treatment of geothermal production (depletion allowance a n d deductions for intangible drilling costs) a n d use (energy
investment tax credits for non-utility investors)
state a n d local government actions t o foster geothermal development.
Success of Industry Exploration
Industry initiated geothermal e x p l o r a t i o n long
before government interest in t h e use of the resource
developed. F r o m a historical perspective, the wells drilled
a t T h e Geysers in the 1920s a r e the earliest identified in the
literature, although modern exploration appears t o begin
in 1955 with t h e M a g m a Power Co. exploratory work a t
T h e Geysers. Data compiled f o r t h e 1982 D O E report
H , ~ y l r o t h c w i wInclirstriuli--uiion:
l
Elwtric. Porcw S . I . . Y I ~ ~ I ~ . Y
I)c\,clopnit~nto n ex p I o ra t i o n in the major geot he r ma I
areas of interest show that M a g m a was also the first
company t o explore in Nevada -- a t Beowawe a n d Brady
Hot Springsareas in 1959 a n d 1960 respectively. As identified by t h e study, the subsequent participants in geothermal exploration in t h e major areas have been a b o u t
e q u a l l y divided between oil c o m p a n i e s , o r their
subsidiaries, a n d companies organized specifically for geothermal development.
Of the 27 hot-water a r e a s listed by the report as
having high a n d moderate levels of development activity,
15 a r e t h e sites of existing power plants, plants under
construction, o r planned plants
Area
California
Operation in 1982
No. B r a w l e y
C o s 0 Hot Sprints
East M e s a
Heber
M o n o - L o n g Valley
Salton S e a / N i l a n d
Westmorland
UNOCAL
C a l i f o r n i a Energy
Magma, Republic
Chevron
Chevron, Union
U n i o n , M a g m a , Republic
ReDublic
Nevada
Beowawe
B r a d y Hot Springs
D e s e r t Peak
D i x i e H o t Springs
S t e a m b o a t Springs
Chevron, Vulcan Thermal
Magma
Phillips
Sunedco
Nevada Thermal
Oregon
Vale Hot Springs
Republic, A M A X
Utah
Cove Fort/Sulphurdale
Roosevelt Hot Springs
Union, M o t h e r Earth
Phillips
Geothermal Resources Council BULLETIN June 1986
Vale Hot Springs is also the sight of a large mushroom-growing facility utilizing the geothermal resource;
the wells at Raft River, Idaho, and a t the Valles Caldera,
New Mexico, were drilled as D O E experimental wells;
a n d d e v e l o p m e n t is inhibited by e n v i r o n m e n t a l
considerations at Lassen, California.
The other areas o n the list not currently scheduled for
power development include:
Surprise Valley, C A
Crane Creek/ Cove Creek, I D
Humboldt House, N V
S a n Emedio, N V
S o d a Lake, N V
Stillwater, N V
Alvord, O R
C r u m p Hot Springs, O R
Accurate Resource Assessment
(*
In the IO-year period preceding the initiation ofdirect
government involvement in geothermal energy, various
organizations and individuals produced estimates of the
g e o t h e r m a l resources of the United States. These
estimates tended to vary widely, partially d u e t o the
differing assumptions and parameters that were chosen,
but mostly because of a n inadequate understanding of the
nature and occurrence of geothermal resources.
In 1974, the U.S. Geological Survey initiated a comprehensive assessment of the geothermal resources of the
United States which was published in 1975 a s U.S. Geological Survey Circular 726. This was the first systematic
effort t o estimate the geothermal resource potential of the
U.S., and t o create methodology and framework for
directing long-term energy policy and strategy.
I n 1978, the USGS reevaluated the geothermal
resources of the United States in light of new available
nonproprietary d a t a a n d refinements in geothermometry
(U.S. Geological Survey Circular 790). T h e estimate for
the number of hydrothermal systems with temperatures
over 9 0 ° C (excluding those in national parks) dropped
from 283 in 1974 t o 215 in 1978 (Table I ) .
The first quantitative assessment of thermal energy
contained within low- a n d moderate-temperature systems
(less than 90°C and 150°C respectively) was completed by
the U S G S in 1982 (U.S. Geological Survey Circular 892).
Data for the assessment were generated by “Resource
Assessment” ( R A ) teams through cooperative Department of Energy a n d State direct use program agencies.
T h e results of these data gathering activities were
published as a series of reports a n d state geothermal maps
for prospective direct heat users.
This information, in addition to that generated by the
U S G S Geothermal Research Program a n d the Regional
Aquifer System Analysis Program, was entered i n t o the
computer-based G E O T H E R M system maintained by
USGS. D a t a o n more t h a n 2500 individual geothermal
systems were evaluated.
The results of the U S G S geothermal assessments are
summarized in Table I .
Extended Geothermal Data Base
When interest in geothermal utilization mounted in
the 1970s, a working d a t a base for geothermal resources
did not exist. Energy companies, in o r d e r to protect land
a n d resource positions, tended t o guard exploratory a n d
development d a t a a s proprietary, a n d there were n o other
sources of d a t a d u e to the “newness” of interest in the
resource.
I n response to this problem, a number of programs
were initiated by DOE’S predecessor, E R D A , i n the mid1970s. T h e Industry-Coupled Cost-Shared Program was
TABLE 1
COMPARISONS OF USGS ESTIMATES OF IDENTIFIED GEOTHERMAL
R E S O U R C E S W I T H I N T H E U N I T E D S T A T E S F R O M 1975 T O 1982
RESOURCE
CATEGORY
i2
LL
a
n
>
I
o
PF
Vapor Dominated
Hot Wafer >15OoC
ACCESSIBLE
RESOURCE BASE
(10”J)‘
1975 1978 1982
1
1
--
79
100
--
61
51
--
1000
850
--
ACCESSIBLE FLUID
RESOURCE BASE
(10”J) *
1975 1978 1982
:gl,NA.
Warm Water < 9p-c
IGNEOUS RELATED
__
__
42
--
--
__
-_
--
48
55
-- 105,000 63,000
--
--
27,000
RESOURCE
(10”J) *
1975 1978 1982
__
_--
-_
__
93
250
210
--
--
-_
__
8
-_
360
176
--
--
--
--
__
CONDUC-
GEOPRESSURED
I
NUMBER OF SYSTEMS EVALUATED
1975 1978 1982
___
71,000
170,000
--
360 IO 430 to
2300
4400
--
__
__
--
_-
__
--
--
56
--
-_
(NOTE Values reported exclude National Parks)
*
Geothermal Resources Council BULLETIN June 1986
lo’*J
=
APPROXIMATELY 1 OUAD
Page 15
organi7ed t o evaluate selected high-temperature geothermal systems; t h e State-Coupled Resource Assessment
( K A ) Program undertook t o compile regional geothermal
d a t a ; a n d the User-Coupled Confirmation Drilling Prog r a m provided a means of cost-sharing the high frontend
risk portion of direct use exploratory drilling.
The I N D U S T R Y - C O U P L E D P R O G R A M was initiated to accelerate the commerciali7ation of geothermal
energy by ( 1 ) stimulating industry exploration efforts
through cost ( a n d thereby risk) sharing, (2) making d a t a
generated from the program available f o r unrestricted
use, (3) developing case histories of geothermal exploration techniques, a n d (4) confirming resource potential a t
selected geothermal sites. T h e program included 2 1 deep
exploratory wells with a n average d e p t h of a b o u t 7000
feet, numerous shallow thermal gradient test holes, a n d
geoscience investigative surveys (Figure 2 a n d Table 2).
Nine major d a t a packages with details of these results
may be studied free-of-charge a t the University of Utah
Research Institute, Earth Science Library in Salt Lake
City, o r may be purchased by mail. A geothermal sample
library containing cuttings a n d core samples from various
DOE-sponsored programs is also maintained a t U U R I , '
E S L for study.
T h e S T A T E - C O U P L E D R E S O U R C E ASSESSM E N T program was organized around geoscience expertise from state geological surveys, universities, a n d state
water resource agencies (Figure 3). Phase I centered o n the
APPROXIMATE SCALE
0
1 Roosevett H S
8
0
10
11
12.
13.
14.
2 Cove For(
3 Banazor
4 Tuscarora
6 . McCoy
6. Laach H.S.
7. Colado
AWORK AREAS
Beorawe
San Emidno
Soda Lake
Stlllwater
Dixie Valley
Dseert Peak
Humboil House
I
Figure 2
Table 2
SUMMARY OF INDUSTRY-COUPLED PROGRAM EFFORTS
AREA
COMPANY
TPC
SEI
UD
G
GRAVITY
GROUND MAG
AERO MAG
ELECTRICAL
RESISTIVITY
0
. .... . ..
.. . . . .. . .. .. .. . .
.
.
.. . . . ..
.
. . . . ........
. . .. .. . . . . . .. . . . .
.
. .
GPC
.
POTENTIAL
SEISMIC
EMISSIONS
0
0
0
.
0
.
AM
AM
G
G
0
.
m
m
m
C
C
C
U
SR
P
P
0
.
0
.
0
.
.
.
.
.
.
.
0
.
0
.
.
.
e
.
0
0
.
0
.
e
.
.
0
.
.
.
COMPANY ABBREVIATIONS
.
0
SHALLOWTHER
MAL GRADIENT
A0
0
0
SEISMIC
REFLECTION
Page 16
-
0
MICRO
EARTHOUAKE
EXPLORATORY
EPP
e
MT AMT
DEEP THER-
U
0
.
TPC
SEI
UD
G
GPC
U
EPP
AM
A0
C
SR
P
Thermal Power Co
Seismic Expioralion lnc
University 01 Denver
Gelty Oil Co
Geothermal Power Corp
Union Oil Co
Earlh Power Production
Amax Exploration lnc
Aniinoll USA lnc
Chevron Oil Co
Southland Royalty
Phillips Petroleum Co
Geothermal Resources Council BULLETIN June 1986
gathering of temperature, chemical. and productivity d a t a
from known thermal springs a n d wells in order to define
a n d prioriti7e new low- t o moderate-temperature
geothermal exploration targets. Data compiled were
contributed to G E O T H E R M . In Phase 11, regional
reconnaissance involved a more detailed look a t the
geothermal d a t a gathered in Phase I in order to refine
exploration target models a n d to outline optimum geot he r ma 1 e n v i r o n me n t s.
STATE-COUPLED PROGRAM PARTICIPANTS
financial incentives t o promote t h e a d o p t i o n of specific
technologies. F r o m a n initial submission of 25 proposals,
nine were selected for participation. This number was
later reduced to four, a n d subsequent problems with
prosper financing reduced the final number of projects t o
two, o n e a t Alamosa, C o l o r a d o , a n d the other in the
Wendel-Amedee area near Honey Lakc in northern California. A production well a t Alamosa was shut-in a n d
abandoned after testing. T h e well a t Honey Lake may be
used t o provide low-temperature fluids for a hybrid binary
power plant under development by GeoProducts Co.
Improvernents in Predictive Techniques
PRINCIPAL CONTRACTING AGENCIES
EZBSTATE
SURVEYS
LMWERSITES
=DEPARTMENT
OF WATER RIQHTS
FIGURE 3
Publication o f 18 state maps depicting thermal
springs a n d wells (temperature, flow, d e p t h , a n d TDS),
areas potentially favorable for new discovery, and the
outline of federal a n d state K G R A s was a n important part
o f t h e State-Coupled Program. They a r e available
through the National Oceanic a n d Atmospheric Administration. More technical maps f o r New Mexico a n d California were also produced. During the course of the
program, over 150 detailed studies were performed a t
selected sites in the states identified in Figure 3.
T h e effect of these programs o n t h e success of geothermal commercialization will not be fully realized for a
number of years. Data developed from t h e IndustryCoupled program, however. a r e undoubtedly aiding geothermal electric power development in the Basin a n d
Range.
The U SER-COtJ P L E D CON FI R M ATION DR ILLl N G P R O G R A M was initiated in 1980 t o promote direct
uses of geothermal energy by establishing a predetermined
cost-share schedule with a n industry participant based
upon t h e d e g r e e ofsuccess o f t h e project. I t was modified,
however, by a shift in D O E policy away from direc!
Geothermal Resources Council BULLETIN June 1986
In the late 1960s a n d early 1970s, exploration
methods for geothermal energy were adapted from the
petroleum and mining industries, o r were based upon
methods used in historically established geothermal areas
(i.e., T h e Geysers a n d Larderello, Italy), with only partial
success. T h e nccd t o develop better predictive methods
became evident when exploration moved t o the liquidd o m i n a t ed ge o t her m a 1 en v i r o n men t s.
A number of programs sponsored by D O E a n d
IJSGS over the past few years have addressed these problems. Case history development from DOE'S IndustryCoupled Program identified the suitability a n d limitations
o f various exploration methods a n d were subsequently
modified to account for t h e nature ofgeothermal systems.
Improvements in chemical gcothermometry by the
USGS a n d others have allowed for the determination of
prospective geothermal targets. Early interest in the mid
1960s o n silica concentrations of natural water systems
evolved through the use of sodium, potassium, and calcium concentrations in empirically-derived equations.
Correction factors f o r these equations using other
dissolved constituents (e.g., magnesium) were later introduced t o better estimate reservoir equilibration temperat u r e . State-of-the-art m e t h o d s in chemical geothermometry currently incorporate t h e use of chemical
thermodynamics a n d kinetics in the development of
mixing models.
USGS research efforts have paralleled DOE'S by program interaction a n d ongoing scientific research. Major
geoscience accomplishments of the Geothermal Research
Program of the USGS include:
multidisciplinary studies of selected geothermal
regions
geothermometry development
electrical a n d e l e c t r o m a g n e t i c t e c h n i q u e d e velopment
refinement of passive a n d active seismic methods
mathematical modeling of hydrologic systems.
T h e current D O E emphasis in hydrothermal reservoir research is directed a t parameters that individually
characterize producing hydrothermal systems. Research
is under way for improvements in techniques to predict
reservoir behavior under longterm production: injection
of geothermal brines a n d t o determine reservoir limits a n d
c o n t ro 11i ng factors.
Various exploration methods, their usefulness, a n d
present status a r e summarized in Table 3.
Page 17
TABLE 3
USEFULNESS AND PRESENT STATUS OF VARIOUS EXPLORATION TECHNIQUES
METHOD
STATUS
APPLICATION
Direct detection
Currently recognized as most valuable indicator of
thermal anomaly
2 Gravity
Low-cost delineation of Shallow Basin
Structure
Better resolution with improvements in quantitative
numerical modeling
3 Electrical Resistivity
Low Resistivity Zones related to hot fluid
circulation Best detection of h i g h angle
structures
Numerical modeling techniques help produce
intrinsic resistivity maps to depths of 500M
4 MTIAMT
Although used for detection to great depths
can be limited by surficial conductors
Research for application still ongoing
5 Sell Potential
Low-cost detection of Basin Structure Best in
late stage of exploration
Utility uncertain
6 Passive Seismic
Detection of seismic emissions related to
hydrothermal activity
Recognition of limitations within areas of thick
alluvial cover Method may not be cost-effective
7 Reflection Seismic
Cost-effective delineation of Border Faults and
depth of alluvial fill
Improvements in digital processing may reduce
problems associated with near-surface volcanics
8 Magnetics
Aeromagnetic surveys useful in determining
regional structure
Identified limitations include interference from
Reversely Polarized volcanic units prism model
development interaction in complex geologic settings
9 Geologic Mapping
Low-cost regional and area studies
Currently recognized as important component to
site-specific exploration programs especially
where faults intersect
Estimating reservoir equilibration temperature
State-of-the-art methods include t h e use of
chemical thermodynamics development of mixing models and studies of isotope fractionation
Isotope ratios give a simple and cheap initial idea 01
thermal conditions
1
Thermal Gradient/Heat
Flow
10 Geochemistry
Advanced Drilling Techniques
In 1975, a federal program was initiated t o improve
rotary techniques for geothermal drilling in the hot,
corrosive. a n d hard fractured rock geothermal environment. Since 1977, this program has been managed at
Sandia National Laboratories, Albuquerque, New Mexico.
T h e near-term goal of this research is to bring a b o u t a 25
percent cost reduction in conventional geothermal drilling. In the long term, a 50 percent cost reduction through
the implementation of advanced drilling techniques is
targeted.
Drilling Hardware: O n e of the success stories in the
geothermal R&D program is the unique a d a p t a t i o n of
PDC ( p o l w r ~ ~ s t u l l i ndiamond
e
compact) cutters to drill
bits. By 198 I , five percent of all bits sold in the U.S. were
P D C bits, a n d it has been estimated that this share will
increase t o 50 percent by 1990, with a large percentage used
for oil drilling.
The Sandia hit hJdraulics test stand permits the fluid
flow a r o u n d drill bits t o be visualized a n d has indicated
that some cutters in commercial drill bits were poorly
situated. Similiar facilities have since been installed by a t
least one major bit manufacturer for use in improved bit
design and cutter placement.
An unsealed roller cone bit and the required high
temperature lubricants for this equipment are now o n the
Page 18
market as a result of this program. Currently, the wear
resistance of a much less expensive refractory material,
niobium carbide, is being tested to determine the suitability of this material a s a replacement f o r tungsten i n
hit inserts.
T h e use of cavitating nozzles h a s been pioneered to
increase the efficiency of conventional drill bits. These
no7zles cause bubbles t o f o r m in the fluid exiting the
drill bit. W h e n the bubbles c o n t a c t the rock surface,
they collapse violently, weakening t h e rock a n d aiding
the drill bit cutters.
Non-conventional drilling systems that were develo p e d a s far a s p r o t o t y p e designs include the chain hit,
with d o w n h o l e replaceable cutters, a n d t h e Terra-clrill,
a bit t h a t fires c e r a m i c projectiles (bullets) into the
f o r m a t i o n t o weaken it a n d increase the drilling rate.
In o r d e r t o i m p r o v e drill bits a n d associated tools,
S a n d i a is seeking t o increase the knowledge of d o w n hole c o n d i t i o n s t h r o u g h d r i l l s t r i n g dj’namics modeling.
T h e i m p o r t a n c e of t h i s p r o j e c t t o i n d u s t r y is
d e m o n s t r a t e d by t h e fact t h a t there a r e five industry
co-sponsors ( N L Baroid, Mobil Oil, Sohio, Conoco, and
Arco). Downhole conditions are also simulated by
G E O T E M R a computer program that calculates the
temperature profile in a well, a n d downhole drilling mud
properties a r e measured on-site by a high-temperature,
high-pressure. viscotnetor.
Geothermal Resources Council BULLETIN June 1986
Drilling Nuids: A major contribution of the federal
geothermal program is the development of high-temperature geothermal drilling fluids. T h e temperature range of
conventional muds can be increased by using jihrous
claj..sdeveloped by the on-going clay studies program, a n d
aqiiroir.s~f~~ain,s
that can survive temperatures up t o 260°C
(500" F) have been pioneered.
Lost Circulation: Loss of drilling fluid into
fractured or high permeability zones is the most costly
problem in geothermal drilling overall. T h u s , a Lost
Circulation Test Facility has been constructed a n d is used
for simulating downhole tests of potential lost circulation
tiiuteriuls. Coi?iputi'r inodels are also being used to
identify the "ideal" lost circulation fluid.
Instrumentation: Significant advances in the develo p me n t of hi~~h-tenipr.rati~rP
&ctronic:~ have been mad e.
C o m p o n e n t development has resulted in a 275°C (527" F)
opera t i o na 1 a m p li f ie r , mu 1t i plexor . a nd hybrid circuit r y
(voltage regulators, line drivers, pulse stretchers, V / F
converters).
Experimental logging tools have also been developed, including the Wellhore Inertial Navigator (borehole
directional survey accurate to 1 m / 1000 m depth) and the
prototype High- Tetnperature Acoustic Borehole. Tc.1~\ > i u t w(capable of operating t o 275°C ( 5 2 7 ° F ) ). T h e
televiewer has been successfully run for the Geothermal
Division of Union Oil in the Imperial Valley, yielding
valuable information on easing condition and fracture
location. Temperature sensors a n d a variable logging
speed capability are being added to the televiewer to
modify i t for use as a Lost Circulation Zoni. Mapping
Too1.
O t h e r o n g o i n g project, include the High- Temporatiirc Cement Bond Log Tool, High- Tc.t?ipr~raturt~
Mono-Cable Toolr (temperature, pressure, and flow measurement$ for production/ injection logging), and the
Radar Fracture Mapping Tool ( u w g V H F electromagnetic 5ignals to "see" fractures ten\ of meters away from
the borehole)
Improvements in Materials
Initial g e o t h e r m a l e n e r g y projects b o r r o w e d
materials a n d fluid engineering techniques from other
industrial applications, largely oil production. Short well
a n d equipment life a n d ; or low process efficiency resulted
because of the high-temperature, corrosive geothermal
environment. In addition, numerous, a n d occasionally
very costly, materials failures were experienced in the
field, d u e to the unavailability of appropriate materials; a
lack of awareness of suitable materials already existing; or
a lack of knowledge a b o u t geochemical characteristics
a n d behavior. Inefficient or ineffective components and
systems often prevented the constant monitoring a n d data
analysis required t o maintain peak performance and
avoid downtime of even a properly designed energy
facility. The materials problems faced by the geothermal
industry in the 1970s, the DOE R&D response, and the
materials breakthroughs that are now available as "offthe-shelf" products a n d components are identified in
Table 4. 0
Part 2 Developments in Power Conversion Technology
will be run in the July 1986 Issue of the BULLETIN.
Table 4
MATERIALS PROBLEMS I N GEOTHERMAL DEVELOPMENT - DOE MATERIALS PROGRAMS, SOLUTIONS/IMPROVEMENTS
PROBLEMS
High cost of materials
due to
- High temperalures
and pressures
- Corrosive and erosive
fluids
- Short lifetime
L a c k of imaterials p e r formance data
Fouling and scaling
Poor understanding of fluid
behaviorlcomplex chemistry
Unreliable sampling and
anaylsis procedures
SOLUTIONS/IMPROVEMENTS
DOE PROGRAM OBJECTIVES
Identify alternate high-temperature
corrosion-resistant materials to costly metals
for borehole and energy conversion corn
portents
Mathematical model to
c a I Cu l a t e l e m p e r a t u r e
changes in wells
Wear resistant tungsten carbide
and Ni-Cr-Si-Blineshanpumpcoatings
Test corrosion inhibitors and monitor
High temperature equipment and materials
- h y b r i d electronic c i r -
mend drill bit
Research cathodic and anodic pro
tectron
Develop corrosion data base
Develop improved downwell and power
plant instrumentation
Collect analyze
performance data
and document field
Develop solids and scale control
methods
Model scale deposition and multi-ion fluids
Develop sensors for monitoring
Chemical and kinetic studies
Measure injectabilrty of brine
Evaluate existing sampling and analysis
methods and develop new techniques
Geothermal Resources Council BULLETIN June 1986
Improved roller cone bits dia
Cults
elastomeric seals and
n-rinns
a- open hole packer
- well completion cement
- iubricar'ts grease and
mud
- downhole electric c a ble and cablehead
equipment
Effective carbonate scale control agent
Flash crystallization / t h i c k
-
Corrosion
equip
ment and materials
- downhole flow meter
- well casing materials
- polymer concrete
- downhole pumps
- pressure lubrication
system
- non-metallic heat e x changer tubing
Steels for improved drill brt lrfe
for fluids up to 400°C
*
enlng process
Binary system teak detector l e g
sensors, particle counters)
On-line suspended solids
monitor for inlection
Summary document on sampling /analysis techniques
Guidelines/handbooks on
materials selection high temperature electronic Components and inlection treatment
Page 19