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• 41. [Image] Comparative assessment of five potential sites for hydrothermal-magma systems: energy transport

  	A comparative assessment of five sites is being prepared as part of a Continental Scientific Drilling Program (CSDP) review of thermal regimes for the purpose of scoping areas for future research and drilling ...
  	Citation × Citation Citation Abstract Copy Title: Comparative assessment of five potential sites for hydrothermal-magma systems: energy transport Author: Hardee, H.C. Year: 1980 A comparative assessment of five sites is being prepared as part of a Continental Scientific Drilling Program (CSDP) review of thermal regimes for the purpose of scoping areas for future research and drilling activities. This background report: discusses the various energy transport processes likely to be encountered in a hydrothermal-magma system, reviews related literature, discusses research and field data needs, and reviews the sites from an energy transport viewpoint. At least three major zones exist in the magma-hydrothermal transport system: the magma zone, the hydrothermal zone, and the transition zone between the two. Major energy transport questions relate to the nature and existence of these zones and their evolution with time. Additional energy transport questions are concerned with the possible existence of critical state and super-critical state permeable convection in deep geothermal systems. A review of thermal transport models emphasizes the fact that present transport models and computational techniques far outweigh the scarcity and quality of deep field data. Title: Comparative assessment of five potential sites for hydrothermal-magma systems: energy transport Author: Hardee, H.C. Year: 1980 A comparative assessment of five sites is being prepared as part of a Continental Scientific Drilling Program (CSDP) review of thermal regimes for the purpose of scoping areas for future research and drilling activities. This background report: discusses the various energy transport processes likely to be encountered in a hydrothermal-magma system, reviews related literature, discusses research and field data needs, and reviews the sites from an energy transport viewpoint. At least three major zones exist in the magma-hydrothermal transport system: the magma zone, the hydrothermal zone, and the transition zone between the two. Major energy transport questions relate to the nature and existence of these zones and their evolution with time. Additional energy transport questions are concerned with the possible existence of critical state and super-critical state permeable convection in deep geothermal systems. A review of thermal transport models emphasizes the fact that present transport models and computational techniques far outweigh the scarcity and quality of deep field data. Close

• 42. [Image] Preparation of a Handbook on the Economics of Geothermal Energy Developments; Working Paper No. 6.5 Case Studies of Low Enthalpy Geothermal Energy Developments in France

  	The use of medium and low temperature brines from deep aquifers is well established technology in France. Agence Francaise Pour La Maitrisse de L'Energy (AFME) (1983) report that since 1978 twenty geothermal ...
  	Citation × Citation Citation Abstract Copy Title: Preparation of a Handbook on the Economics of Geothermal Energy Developments; Working Paper No. 6.5 Case Studies of Low Enthalpy Geothermal Energy Developments in France Author: Harrison, R. Year: 1984 The use of medium and low temperature brines from deep aquifers is well established technology in France. Agence Francaise Pour La Maitrisse de L'Energy (AFME) (1983) report that since 1978 twenty geothermal schemes have been put into operation every year and it is foreseen that France will have an installed geothermal heating capacity equivalent to an annual saving of 106 TOE* similar developments. Thus Ungemach (1982) reports that three schemes are under completion in the Po Valley in Italy and that several demonstration projects; e.g. Southampton in the U.K. + and in Denmark and Holland are under examination for the near future. It is estimated that the European Economic Community could have a geothermal heating capacity equivalent to 2 x 106 TOE by the late 1990's, Ungemach (1983) Title: Preparation of a Handbook on the Economics of Geothermal Energy Developments; Working Paper No. 6.5 Case Studies of Low Enthalpy Geothermal Energy Developments in France Author: Harrison, R. Year: 1984 The use of medium and low temperature brines from deep aquifers is well established technology in France. Agence Francaise Pour La Maitrisse de L'Energy (AFME) (1983) report that since 1978 twenty geothermal schemes have been put into operation every year and it is foreseen that France will have an installed geothermal heating capacity equivalent to an annual saving of 106 TOE* similar developments. Thus Ungemach (1982) reports that three schemes are under completion in the Po Valley in Italy and that several demonstration projects; e.g. Southampton in the U.K. + and in Denmark and Holland are under examination for the near future. It is estimated that the European Economic Community could have a geothermal heating capacity equivalent to 2 x 106 TOE by the late 1990's, Ungemach (1983) Close

• 43. [Image] Geothermal Loop Experimental Facility. Quarterly Report, October--December 1978

  	Since the Geothermal Loop Experimental Facility (GLEF) start-up in May, 1976, a substantial amount of information has been obtained on the operation of the plant, components, brine and steam composition, ...
  	Citation × Citation Citation Abstract Copy Title: Geothermal Loop Experimental Facility. Quarterly Report, October--December 1978 Author: Anastas, G. Year: 1979 Since the Geothermal Loop Experimental Facility (GLEF) start-up in May, 1976, a substantial amount of information has been obtained on the operation of the plant, components, brine and steam composition, production and injection wells, and the potential of the Niland Reservoir. The GLEF was modified in April, 1978, from a four stage flash/binary process to a two stage cycle for the extraction of energy from a high temperature, high salinity, liquid dominated resource. This quarterly summarizes the general operations and accomplishments of the GLEF during the period from October 1, 1978 through December 31, 1978 Title: Geothermal Loop Experimental Facility. Quarterly Report, October--December 1978 Author: Anastas, G. Year: 1979 Since the Geothermal Loop Experimental Facility (GLEF) start-up in May, 1976, a substantial amount of information has been obtained on the operation of the plant, components, brine and steam composition, production and injection wells, and the potential of the Niland Reservoir. The GLEF was modified in April, 1978, from a four stage flash/binary process to a two stage cycle for the extraction of energy from a high temperature, high salinity, liquid dominated resource. This quarterly summarizes the general operations and accomplishments of the GLEF during the period from October 1, 1978 through December 31, 1978 Close

• 44. [Image] A National Plan For Energy Research Development & Demonstration, Volume 1: The Plan

  	Imports, in the form of petroleum, petroleum products, and natural gas account for 20 percent of the total domestic energy consumption, at an annual cost of over $25 billion in 1974. This heavy reliance ...
  	Citation × Citation Citation Abstract Copy Title: A National Plan For Energy Research Development & Demonstration, Volume 1: The Plan Author: Seamans, R. C. Jr. Year: 1975 Imports, in the form of petroleum, petroleum products, and natural gas account for 20 percent of the total domestic energy consumption, at an annual cost of over $25 billion in 1974. This heavy reliance on imported energy has serious national security implications. Dependence on imports makes the United States vulnerable to undesirable external influences on U.S. foreign and domestic policy. Foreign powers can threaten life styles and economic stability by curtailing the supply of petroleum or effecting arbitrary and sudden price changes. The quadrupling of the world price of petroleum in the past two years has disrupted the U.S. economy and the economies of all other importing nations Title: A National Plan For Energy Research Development & Demonstration, Volume 1: The Plan Author: Seamans, R. C. Jr. Year: 1975 Imports, in the form of petroleum, petroleum products, and natural gas account for 20 percent of the total domestic energy consumption, at an annual cost of over $25 billion in 1974. This heavy reliance on imported energy has serious national security implications. Dependence on imports makes the United States vulnerable to undesirable external influences on U.S. foreign and domestic policy. Foreign powers can threaten life styles and economic stability by curtailing the supply of petroleum or effecting arbitrary and sudden price changes. The quadrupling of the world price of petroleum in the past two years has disrupted the U.S. economy and the economies of all other importing nations Close

• 45. [Image] A National Plan for Energy Research, Development and Demonstration: Creating Energy Choices for the Future. 1976. Volume 2. Program Implementation

  	The Building Blocks in Parts II and III describe programs whose objectives are supportive in nature and often cut across several energy technologies. The eight Building Blocks contained in Part II are ...
  	Citation × Citation Citation Abstract Copy Title: A National Plan for Energy Research, Development and Demonstration: Creating Energy Choices for the Future. 1976. Volume 2. Program Implementation Author: United States Energy Research and Development Administration Year: 1976 The Building Blocks in Parts II and III describe programs whose objectives are supportive in nature and often cut across several energy technologies. The eight Building Blocks contained in Part II are divided into Two major program areas: Environmental Research and Safety, and Basic Energy Sciences. The six activities contained in Part III are not unique to energy RD&D but are necessary for achievement of its objectives. Part IV consists of three tables. They contain cross-referencing data that will allow the reader to examine the Building Blocks from the different perspectives of the National Energy Technology Goals, Volume 1 Technologies, and Federal Agency Involvement Title: A National Plan for Energy Research, Development and Demonstration: Creating Energy Choices for the Future. 1976. Volume 2. Program Implementation Author: United States Energy Research and Development Administration Year: 1976 The Building Blocks in Parts II and III describe programs whose objectives are supportive in nature and often cut across several energy technologies. The eight Building Blocks contained in Part II are divided into Two major program areas: Environmental Research and Safety, and Basic Energy Sciences. The six activities contained in Part III are not unique to energy RD&D but are necessary for achievement of its objectives. Part IV consists of three tables. They contain cross-referencing data that will allow the reader to examine the Building Blocks from the different perspectives of the National Energy Technology Goals, Volume 1 Technologies, and Federal Agency Involvement Close

• 46. [Image] Geothermal Energy Omnibus Legislation Recommendations of the Institutional Barrier Panel to the Interagency Geothermal Coordinating Council

  	Three major pieces of legislation have been passed since 1970 to promote the development of geothermal resources in the U.S. These are the Geothermal steam act of 1970 (PL 91-581,the Geothermal Energy ...
  	Citation × Citation Citation Abstract Copy Title: Geothermal Energy Omnibus Legislation Recommendations of the Institutional Barrier Panel to the Interagency Geothermal Coordinating Council Author: Geothermal Division, US Department of Energy Three major pieces of legislation have been passed since 1970 to promote the development of geothermal resources in the U.S. These are the Geothermal steam act of 1970 (PL 91-581,the Geothermal Energy Research, Development, and Demonstration Act of 1974P-4,and the five Acts that made up the 1978 National Energy Act - the Public Utility Regulatory Policies Act of 1978 -(a_95-61.7), the Energy Tax Act of 1978 OM 95-618), the National Energy Conservation Policy Act OM 65-619), the Power Plant and Industrial Fuel Use Act of 1978 (PL 95-620), and the Natural Gas Policy Act of 1978 (PL 95-621). These initiatives go a long way toward establishing a legal and regulatory framework favorable to commercial geothermal energy exploration and development, and incentives to stimulate early and widespread use by a variety of users. However, all of these acts require improvements if the geothermal energy utilization objectives of the Council are to be met. Consequently, the Institutional Barrier Panel has developed a recommended Geothermal Energy Omnibus 1 Bill to complete the legislative needs Title: Geothermal Energy Omnibus Legislation Recommendations of the Institutional Barrier Panel to the Interagency Geothermal Coordinating Council Author: Geothermal Division, US Department of Energy Three major pieces of legislation have been passed since 1970 to promote the development of geothermal resources in the U.S. These are the Geothermal steam act of 1970 (PL 91-581,the Geothermal Energy Research, Development, and Demonstration Act of 1974P-4,and the five Acts that made up the 1978 National Energy Act - the Public Utility Regulatory Policies Act of 1978 -(a_95-61.7), the Energy Tax Act of 1978 OM 95-618), the National Energy Conservation Policy Act OM 65-619), the Power Plant and Industrial Fuel Use Act of 1978 (PL 95-620), and the Natural Gas Policy Act of 1978 (PL 95-621). These initiatives go a long way toward establishing a legal and regulatory framework favorable to commercial geothermal energy exploration and development, and incentives to stimulate early and widespread use by a variety of users. However, all of these acts require improvements if the geothermal energy utilization objectives of the Council are to be met. Consequently, the Institutional Barrier Panel has developed a recommended Geothermal Energy Omnibus 1 Bill to complete the legislative needs Close

• 47. [Image] Wilcox sandstone reservoirs in the deep subsurface along the Texas Gulf Coast: their potential for production of geopressured geothermal energy. Report of Investigations No. 117

  	Regional studies of the lower Eocene Wilcox Group in Texas were conducted to assess the potential for producing heat energy and solution methane from geopressured fluids in the deep-subsurface growth-faulted ...
  	Citation × Citation Citation Abstract Copy Title: Wilcox sandstone reservoirs in the deep subsurface along the Texas Gulf Coast: their potential for production of geopressured geothermal energy. Report of Investigations No. 117 Author: Debout, D.G. Year: 1982 Regional studies of the lower Eocene Wilcox Group in Texas were conducted to assess the potential for producing heat energy and solution methane from geopressured fluids in the deep-subsurface growth-faulted zone. However, in addition to assembling the necessary data for the geopressured geothermal project, this study has provided regional information of significance to exploration for other resources such as lignite, uranium, oil, and gas. Because the focus of this study was on the geopressured section, emphasis was placed on correlating and mapping those sandstones and shales occurring deeper than about 10,000 ft. The Wilcox and Midway Groups comprise the oldest thick sandstone/shale sequence of the Tertiary of the Gulf Coast. The Wilcox crops out in a band 10 to 20 mi wide located 100 to 200 mi inland from the present-day coastline. The Wilcox sandstones and shales in the outcrop and updip shallow subsurface were deposited primarily in fluvial environments; downdip in the deep subsurface, on the other hand, the Wilcox sediments were deposited in large deltaic systems, some of which were reworked into barrier-bar and strandplain systems. Growth faults developed within the deltaic systems, where they prograded basinward beyond the older, stable Lower Cretaceous shelf margin onto the less stable basinal muds. Continued displacement along these faults during burial resulted in: (1) entrapment of pore fluids within isolated sandstone and shale sequences, and (2) buildup of pore pressure greater than hydrostatic pressure and development of geopressure.; DOE/ET/28461-T2. Title: Wilcox sandstone reservoirs in the deep subsurface along the Texas Gulf Coast: their potential for production of geopressured geothermal energy. Report of Investigations No. 117 Author: Debout, D.G. Year: 1982 Regional studies of the lower Eocene Wilcox Group in Texas were conducted to assess the potential for producing heat energy and solution methane from geopressured fluids in the deep-subsurface growth-faulted zone. However, in addition to assembling the necessary data for the geopressured geothermal project, this study has provided regional information of significance to exploration for other resources such as lignite, uranium, oil, and gas. Because the focus of this study was on the geopressured section, emphasis was placed on correlating and mapping those sandstones and shales occurring deeper than about 10,000 ft. The Wilcox and Midway Groups comprise the oldest thick sandstone/shale sequence of the Tertiary of the Gulf Coast. The Wilcox crops out in a band 10 to 20 mi wide located 100 to 200 mi inland from the present-day coastline. The Wilcox sandstones and shales in the outcrop and updip shallow subsurface were deposited primarily in fluvial environments; downdip in the deep subsurface, on the other hand, the Wilcox sediments were deposited in large deltaic systems, some of which were reworked into barrier-bar and strandplain systems. Growth faults developed within the deltaic systems, where they prograded basinward beyond the older, stable Lower Cretaceous shelf margin onto the less stable basinal muds. Continued displacement along these faults during burial resulted in: (1) entrapment of pore fluids within isolated sandstone and shale sequences, and (2) buildup of pore pressure greater than hydrostatic pressure and development of geopressure.; DOE/ET/28461-T2. Close

• 48. [Image] Geothermal Environmental Impact Assessment: Subsurface Environmental Assessment for Four Geothermal Systems

  	Geothermal systems are described for Imperial Valley and The Geysers, California; Klamath Falls, Oregon; and the Rio Grande Rift Zone, New Mexico; including information on location, area, depth, temperature, ...
  	Citation × Citation Citation Abstract Copy Title: Geothermal Environmental Impact Assessment: Subsurface Environmental Assessment for Four Geothermal Systems Author: Geonomics, Inc. Year: 1978 Geothermal systems are described for Imperial Valley and The Geysers, California; Klamath Falls, Oregon; and the Rio Grande Rift Zone, New Mexico; including information on location, area, depth, temperature, fluid phase and composition, resource base and status of development. The subsurface environmental assessment evaluates potential groundwater degradation, seismicity and subsidence. A general discussion on geothermal systems, pollution potential, chemical characteristics of geothermal fluids and environmental effects of geothermal water pollutants is presented as background material. For the Imperial Valley, all publicly available water quality and location data for geothermal and nongeothermal wells in and near the East Mesa, Salton Sea, Heber, Brawley, Dunes and Glamis KGRAs have been compiled and plotted. The geothermal fluids which will be reinjected range in salinity from a few thousand to more than a quarter million ppm. Although Imperial Valley is a major agricultural center, groundwater use in and near most of these KGRAs is minimal. Extensive seismicity and subsidence monitoring networks have been established in this area of high natural seismicity and subsidence. The vapor-dominated geysers geothermal field is the largest electricity producer in the world. Groundwater in this mountainous region flows with poor hydraulic continuity in fractured rock. Ground and surface water quality is generally good, but high boron concentrations in hot springs and geothermal effluents is of significant concern; however, spent condensate is reinjected. High microearthquake activity is noted around the geothermal reservoir and potential subsidence effects are considered minimal. In Klamath Falls, geothermal fluids up to 113 C (235 F) are used for space heating, mostly through downhole heat exchangers with only minor, relatively benign, geothermal fluid being produced at the surface. Seismicity is low and is not expected to increase. Subsidence is not recognized. Of all geothermal occurrences in the Rio Grande Rift, the Valles Caldera is currently of primary interest. injection of geothermal effluent from hydrothermal production Wells should remove any hydrologic hazard due to some potentially noxious constituents. Waters circulating in the LASL Hot Dry Rock experiment are potable. Seismic effects are expected to be minimal. Subsidence effects could develop Title: Geothermal Environmental Impact Assessment: Subsurface Environmental Assessment for Four Geothermal Systems Author: Geonomics, Inc. Year: 1978 Geothermal systems are described for Imperial Valley and The Geysers, California; Klamath Falls, Oregon; and the Rio Grande Rift Zone, New Mexico; including information on location, area, depth, temperature, fluid phase and composition, resource base and status of development. The subsurface environmental assessment evaluates potential groundwater degradation, seismicity and subsidence. A general discussion on geothermal systems, pollution potential, chemical characteristics of geothermal fluids and environmental effects of geothermal water pollutants is presented as background material. For the Imperial Valley, all publicly available water quality and location data for geothermal and nongeothermal wells in and near the East Mesa, Salton Sea, Heber, Brawley, Dunes and Glamis KGRAs have been compiled and plotted. The geothermal fluids which will be reinjected range in salinity from a few thousand to more than a quarter million ppm. Although Imperial Valley is a major agricultural center, groundwater use in and near most of these KGRAs is minimal. Extensive seismicity and subsidence monitoring networks have been established in this area of high natural seismicity and subsidence. The vapor-dominated geysers geothermal field is the largest electricity producer in the world. Groundwater in this mountainous region flows with poor hydraulic continuity in fractured rock. Ground and surface water quality is generally good, but high boron concentrations in hot springs and geothermal effluents is of significant concern; however, spent condensate is reinjected. High microearthquake activity is noted around the geothermal reservoir and potential subsidence effects are considered minimal. In Klamath Falls, geothermal fluids up to 113 C (235 F) are used for space heating, mostly through downhole heat exchangers with only minor, relatively benign, geothermal fluid being produced at the surface. Seismicity is low and is not expected to increase. Subsidence is not recognized. Of all geothermal occurrences in the Rio Grande Rift, the Valles Caldera is currently of primary interest. injection of geothermal effluent from hydrothermal production Wells should remove any hydrologic hazard due to some potentially noxious constituents. Waters circulating in the LASL Hot Dry Rock experiment are potable. Seismic effects are expected to be minimal. Subsidence effects could develop Close

• 49. [Image] Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California

  	The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California, from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and ...
  	Citation × Citation Citation Abstract Copy Title: Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California Author: Galbraith, R.M. Year: 1978 The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California, from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and extensive geophysical logging surveys were conducted to document the geologic character of the geothermal system as penetrated by CGEH-1. The major rock units encountered include a mafic metamorphic sequence and a leucogranite which intruded the metamorphic rocks. Only weak hydrothermal alteration was noted in these rocks. Drillhole surveys and drilling rate data indicate that the geothermal system is structurally controlled and that the drillhole itself was strongly influenced by structural zones. Water chemistry indicates that this geothermal resource is a hot-water rather than a vapor-dominated system. Several geophysical logs were employed to characterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the acoustics logs indicate fractured rock and potentially permeable zones. A series of temperature logs run as a function of time during and after the completion of drilling were most useful in delineating the zones of maximum heat flux. Convective heat flow and temperatures greater than 350/sup 0/F appear to occur only along an open fracture system encountered between depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet Title: Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California Author: Galbraith, R.M. Year: 1978 The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California, from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and extensive geophysical logging surveys were conducted to document the geologic character of the geothermal system as penetrated by CGEH-1. The major rock units encountered include a mafic metamorphic sequence and a leucogranite which intruded the metamorphic rocks. Only weak hydrothermal alteration was noted in these rocks. Drillhole surveys and drilling rate data indicate that the geothermal system is structurally controlled and that the drillhole itself was strongly influenced by structural zones. Water chemistry indicates that this geothermal resource is a hot-water rather than a vapor-dominated system. Several geophysical logs were employed to characterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the acoustics logs indicate fractured rock and potentially permeable zones. A series of temperature logs run as a function of time during and after the completion of drilling were most useful in delineating the zones of maximum heat flux. Convective heat flow and temperatures greater than 350/sup 0/F appear to occur only along an open fracture system encountered between depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet Close

• 50. [Image] Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California

  	The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and ...
  	Citation × Citation Citation Abstract Copy Title: Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California Author: Galbraith, R.M. Year: 1978 The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and extensive geophysical logging surveys were conducted to document the geologic character of the geothermal system as penetrated by CGEH-1. The major rock units encountered include a mafic metamorphic sequence and a leucogranite which intruded the metamorphic rocks. Only weak hydrothermal alteration was noted in these rocks. Drillhole surveys and drilling rate data indicate that the geothermal system is structurally controlled and that the drillhole itself was strongly influenced by structural zones. Water chemistry indicates that this geothermal resource is a hot-water rather than a vapor-dominated system. Several geophysical logs were employed to characterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the acoustic logs indicate fractured rock and potentially permeable zones. A series of temperature logs run as a function of time during and after the completion of Drilling were most Useful in delineating the zones of maximum heat flux. Convective heat flow and temperatures greater than 350/sup 0/F appear to occur only along an open fracture system encountered between depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet Title: Geological and Geophysical Analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California Author: Galbraith, R.M. Year: 1978 The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and extensive geophysical logging surveys were conducted to document the geologic character of the geothermal system as penetrated by CGEH-1. The major rock units encountered include a mafic metamorphic sequence and a leucogranite which intruded the metamorphic rocks. Only weak hydrothermal alteration was noted in these rocks. Drillhole surveys and drilling rate data indicate that the geothermal system is structurally controlled and that the drillhole itself was strongly influenced by structural zones. Water chemistry indicates that this geothermal resource is a hot-water rather than a vapor-dominated system. Several geophysical logs were employed to characterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the acoustic logs indicate fractured rock and potentially permeable zones. A series of temperature logs run as a function of time during and after the completion of Drilling were most Useful in delineating the zones of maximum heat flux. Convective heat flow and temperatures greater than 350/sup 0/F appear to occur only along an open fracture system encountered between depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet Close