2. Motivation. In 2005, Idaho National Laboratory was studying historical geothermal exploration practices and success ratios for DOE.GHA was contracted to accumulate copies of published literature, internet information, and unpublished geothermal exploration data on currently operating geothermal projects and undeveloped geothermal prospects. .
1. Historical Exploration and Drilling Data from Geothermal Prospects and Power Generation Projects in the Western United States
Jim Combs, Ph.D.
Geo Hills Associates, Reno, NV
GRC 2006 Annual Meeting Technical Program
September 13, 2006 in San Diego, California
3. 3 Motivation Since 1992, no new geothermal reservoir has been developed for power production in the United States.
The U.S. geothermal industry is in need of exploration and development for new power projects to respond to current demand and growing need for secure, environmentally benign, domestic, base-load, renewable geothermal electricity.
4. 4 Historical Background Many prospective geothermal areas were being explored and drilled in the 1950s, 1960s, and early 1970s in the western United States.
In the mid- to late-1950s, Magma Power Company drilled wells near most hot springs in the western U.S. and in 1960 initiated their paying geothermal assets with development of a steam field in The Geysers for a initial PG&E power plant.
5. 5 Historical Background During the 1970s and 1980s in response to the oil crises, at least 19 oil and gas and mining companies were involved in the exploration for geothermal resources and their combined expenditures were at least a billion nominal dollars.
During the period from 1976 to 1985, U.S. Department of Energy (DOE) had a well-funded ($827 million for 10-year period) and focused geothermal R&D program.
6. 6 Historical Background The oil and gas companies included Phillips Petroleum, Chevron Resources, Unocal Geothermal, Santa Fe Geothermal, Shell Oil, Aminoil USA, Burma Oil & Gas, ARCO Petroleum, Anadarko Petroleum, Occidental Petroleum, Getty Oil, Signal Oil & Gas, Earth Power Resources, Hunt Energy, Hunt Oil, and Southland Royalty.
The most prominent mining companies were Amax Exploration and Kennecott Mining.
7. 7 Historical Background Reasons for the oil and gas industry withdrawing in late 1980s from the geothermal industry included the low cost of petroleum power generation fuels.
Few potential geothermal reservoirs had been identified with temperatures greater than 200°C at depths less than 2,000m.
A lack of power purchase agreements (i.e., market) for geothermal power generation projects.
Binary power generation technologies were not proven; thus, petroleum firms essentially exited the domestic geothermal industry.
8. 8 Historical Background
9. 9 Historical Background In late 1977, DOE initiated an Industry-Coupled Drilling Program with geothermal industry entities to accelerate development of high-temperature geothermal resources for power generation.
The program was intended to obtain and release to the public confidential industry data with respect to geothermal exploration and drilling in return for DOE funding deep exploration wells on designated geothermal prospects of which there were 14 in the Basin and Range Physiographic Province of Utah and Nevada.
10. 10 Historical Background
11. 11 Historical Background The resulting database for the 14 geothermal areas included total DOE funding over a 4-yr period from 1978 to 1981 of about $14.5 million with industry contributing an estimated $17 million (Fiore, 1980).
The program contributed directly to new geothermal power generation projects at Beowawe, NV and Cove Fort-Sulphurdale, UT as well as supported power development at Roosevelt Hot Springs, UT; Dixie Valley, NV; Soda Lake, NV; Stillwater, NV; and Empire, NV.
12. 12 Historical Background In his critique of the U.S. DOE Geothermal Program
Review IX, Combs (1991) identified the following
classic geothermal paradox:
“Some companies have found and do find themselves
in a position of having to prove a viable geothermal
resource with little capital to make a long-term power
sales contract secure, which in turn, can be used
to finance the drilling and testing programs to prove
viability of the geothermal power generation project.”
13. 13 Geothermal Exploration and Drilling Data Using the Excel format in the next slide, Combs (2005) gathered exploration and drilling data on 22 geothermal power generation projects. In addition, some 315 geothermal prospects are included in the GHA database.
The 337 geothermal areas can be compared to the 140 geothermal resource sites, forming the basis of the Western Governors’ Association Geothermal Task Force Report (2006).
14. 14 Required Information for Historical Geothermal Exploration and Drilling
15. 15 Partial Table of Historical Data
16. 16 Geothermal Exploration and Drilling Data These published data should be thoroughly evaluated before new surveys and investigations are planned, funded, and conducted. In fact, the historical data may
be the least cost exploration information that can be obtained;
eliminate the need to conduct certain surveys; and
assist in the interpretation of other data collected during the course of the geothermal exploration activities of a geothermal developer.
With the 315 identified geothermal prospects, new exploration ventures should carefully consider the historical exploration and drilling databases.
17. 17 Geothermal Exploration and Drilling Data Under a separate INL contract to SAIC of which the author is a member of the team, as shown earlier Pritchett (2006) noted, based on a series of theoretical calculations, that shallow heat flow is essentially useless for delineating “hidden basin and range type” geothermal resources and thus citing successful geothermal wells.
It appears that the best way to find “hidden” geothermal reservoirs is to reexamine geothermal prospects, which have anomalous thermal gradients and conduct SP, MT, and DC resistivity surveys.
18. 18 Geothermal Exploration and Drilling Data Under a separate INL contract to SAIC the team is to use existing historical data sets from operating Basin and Range geothermal reservoirs to test the utility of electrical surveys for characterizing the subsurface and the geothermal reservoir (Garg, et al., 2006).
Garg and coworkers (2006) earlier presented the results from their analysis and evaluation of the Dixie Valley Geothermal Project to verify results from theoretical calculations of Pritchett (2006). The Beowawe Geothermal Project is now being examined by the SAIC team.
19. 19 Exploration and Drilling Data on Geothermal Prospects and Power Projects
20. 20 Geothermal Exploration and Drilling Data The California Division of Oil, Gas and Geothermal Resources database contains 3,914 well records; however, only 3,427 could be examined. The other 487 deep wells are presently confidential but will be reclassified as open to public during next few years.
Imperial Valley had 1,481 well records, 298 were identified as thermal gradient holes, and 421 were slim holes, exploration and/or commercial wells all being associated with geothermal power projects. Locations for another 770 thermal gradient/heat flow boreholes were not located in the database.
21. 21 Geothermal Exploration and Drilling Data The 770 thermal gradient holes in the Imperial Valley were drilled and reported by Chevron Geothermal (435), Unocal Geothermal (131), Phillips Petroleum (71), Republic Geothermal (69), Occidental Geothermal (30) and the USGS (34). These holes should be located and the temperature-depth data carefully reviewed.
There are 2,737 thermal gradient holes in the GHA database for Nevada; however, of the 122 geothermal prospects and power projects only 39 have data on slim holes, exploration, and/or commercial wells.Thus, there are as many as 83 potential geothermal projects that need confirmation with electrical geophysical surveys, slim holes and exploration wells to define possible geothermal reservoir.
22. 22 Acknowledgments Thanks to Joel Renner of the Idaho National Laboratory (INL) who was conducting a study of past exploration practices and success rates for geothermal resources identification for having the management and operations contractor for INL, i.e., Battelle Energy Alliance, LLC (BEA), to subcontract with Dr. Jim Combs of Geo Hills Associates to assist in the INL efforts (BEA Contract No. 00047375).