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• 141. [Image] Geothermal Reservoir Categorization and Stimulation Study

  	Analyses of the fraction of geothermal wells that are dry (dry-hole fraction) indicate that geothermal reservoirs can be fitted into four basic categories: (i) Quaternary to late Tertiary sediments (almost ...
  	Citation × Citation Citation Abstract Copy Title: Geothermal Reservoir Categorization and Stimulation Study Author: Overton, H.L. Year: 1977 Analyses of the fraction of geothermal wells that are dry (dry-hole fraction) indicate that geothermal reservoirs can be fitted into four basic categories: (i) Quaternary to late Tertiary sediments (almost no dry holes); (ii) Quaternary to late Tertiary extrusives (approximately 20 percent dry holes); (iii) Mesozoic or older metamorphic rocks (approximately 25-30 percent dry holes); and (iv) Precambrian or younger rocks (data limited to Roosevelt Springs where 33 percent of the wells were dry). Failure of geothermal wells to flow economically is due mainly to low-permeability formations in unfractured regions. Generally the permeability correlates inversely with the temperature-age product and directly with the original rock porosity and pore size. However, this correlation fails whenever high-stress fields provide vertical fracturing or faulting, and it is the high-stress/low-permeability category that is most amenable to artificial stimulation by hydraulic fracturing, propellant fracturing, or chemical explosive fracturing. Category (i) geothermal fields (e.g., Cerro Prieto, Mexico; Niland, CA; East Mesa, CA) are not recommended for artificial stimulation because these younger sediments almost always produce warm or hot water. Most geothermal fields fit into category (ii) (e.g., Wairakei, New Zealand; Matsukawa, Japan; Ahuachapan, El Salvador) and in the case of Mt. Home, ID, and Chandler, AZ, possess some potential for stimulation. The Geysers is a category (iii) field, and its highly stressed brittle rocks should make this site amenable to stimulation by explosive fracturing techniques. Roosevelt Springs, UT, Well 9-1 is in category (iv) and is a flow failure. It represents a prime candidate for stimulation by hydraulic fracturing because it has a measured temperature of 227/sup 0/C, is cased and available for experimentation, and is within 900 m of an excellent geothermal producing well Title: Geothermal Reservoir Categorization and Stimulation Study Author: Overton, H.L. Year: 1977 Analyses of the fraction of geothermal wells that are dry (dry-hole fraction) indicate that geothermal reservoirs can be fitted into four basic categories: (i) Quaternary to late Tertiary sediments (almost no dry holes); (ii) Quaternary to late Tertiary extrusives (approximately 20 percent dry holes); (iii) Mesozoic or older metamorphic rocks (approximately 25-30 percent dry holes); and (iv) Precambrian or younger rocks (data limited to Roosevelt Springs where 33 percent of the wells were dry). Failure of geothermal wells to flow economically is due mainly to low-permeability formations in unfractured regions. Generally the permeability correlates inversely with the temperature-age product and directly with the original rock porosity and pore size. However, this correlation fails whenever high-stress fields provide vertical fracturing or faulting, and it is the high-stress/low-permeability category that is most amenable to artificial stimulation by hydraulic fracturing, propellant fracturing, or chemical explosive fracturing. Category (i) geothermal fields (e.g., Cerro Prieto, Mexico; Niland, CA; East Mesa, CA) are not recommended for artificial stimulation because these younger sediments almost always produce warm or hot water. Most geothermal fields fit into category (ii) (e.g., Wairakei, New Zealand; Matsukawa, Japan; Ahuachapan, El Salvador) and in the case of Mt. Home, ID, and Chandler, AZ, possess some potential for stimulation. The Geysers is a category (iii) field, and its highly stressed brittle rocks should make this site amenable to stimulation by explosive fracturing techniques. Roosevelt Springs, UT, Well 9-1 is in category (iv) and is a flow failure. It represents a prime candidate for stimulation by hydraulic fracturing because it has a measured temperature of 227/sup 0/C, is cased and available for experimentation, and is within 900 m of an excellent geothermal producing well Close

• 142. [Image] Preliminary Petrographic and Geophysical Interpretations of the Exploratory Geothermal Drill Hole and Core, Redstone, New Hampshire

  	A 3000 foot diamond drill hole was drilled in the Conway Granite in Redstone, New Hampshire. A comprehensive detailed petrographic and physical study of this core was made. The purpose of this study is ...
  	Citation × Citation Citation Abstract Copy Title: Preliminary Petrographic and Geophysical Interpretations of the Exploratory Geothermal Drill Hole and Core, Redstone, New Hampshire Author: Hoag, R.B. Jr. Year: 1977 A 3000 foot diamond drill hole was drilled in the Conway Granite in Redstone, New Hampshire. A comprehensive detailed petrographic and physical study of this core was made. The purpose of this study is to supply a sound data base for future geothermal and uranium-thorium studies of the drill core. An estimate of the heat flow potential of the Redstone drill hole gives a heat flow of 1.9 HFU. If only the red phase of the Conway Granite had been intersected the heat flow may have been as much as 2.7 HFU, reaching a temperature of 260/sup 0/C at 6 km. The drill hole intersected four lithologies; the green and red phase of the Conway Granite, the Albany quartz syenite and a medium-grained, hastingsite-biotite granite. The red phase has the highest and most irregular radioactivity. The irregularity is mainly due to minor variations in lithology. The Drill core intersected several alteration zones up to a thickness of 150 feet. These alteration zones represent passage of low to medium temperature fluids which might have been mineralized. The Conway Granite has the physical and chemical characteristics necessary for the formation of vein type uranium deposits. The presence of unexplained radiometric anomalies lends support to the existence of such deposits Title: Preliminary Petrographic and Geophysical Interpretations of the Exploratory Geothermal Drill Hole and Core, Redstone, New Hampshire Author: Hoag, R.B. Jr. Year: 1977 A 3000 foot diamond drill hole was drilled in the Conway Granite in Redstone, New Hampshire. A comprehensive detailed petrographic and physical study of this core was made. The purpose of this study is to supply a sound data base for future geothermal and uranium-thorium studies of the drill core. An estimate of the heat flow potential of the Redstone drill hole gives a heat flow of 1.9 HFU. If only the red phase of the Conway Granite had been intersected the heat flow may have been as much as 2.7 HFU, reaching a temperature of 260/sup 0/C at 6 km. The drill hole intersected four lithologies; the green and red phase of the Conway Granite, the Albany quartz syenite and a medium-grained, hastingsite-biotite granite. The red phase has the highest and most irregular radioactivity. The irregularity is mainly due to minor variations in lithology. The Drill core intersected several alteration zones up to a thickness of 150 feet. These alteration zones represent passage of low to medium temperature fluids which might have been mineralized. The Conway Granite has the physical and chemical characteristics necessary for the formation of vein type uranium deposits. The presence of unexplained radiometric anomalies lends support to the existence of such deposits Close

• 143. [Image] Drilling plan: Raft River Geothermal Exploratory Hole No. 3

  	The program, plans, and procedures to be used in drilling and completion of the Raft River Geothermal Exploratory Hole No. 3(RRGE-3) are described. RRGE-3 will be located in the Raft River valley of south ...
  	Citation × Citation Citation Abstract Copy Title: Drilling plan: Raft River Geothermal Exploratory Hole No. 3 Author: Industrial Applications Division , Nevada Operations Office Year: 1976 The program, plans, and procedures to be used in drilling and completion of the Raft River Geothermal Exploratory Hole No. 3(RRGE-3) are described. RRGE-3 will be located in the Raft River valley of south central Idaho, southeast of Burley, and approximately 16 miles south of Malta, Idaho. The third exploratory hole will be drilled to provide data to further investigate and evaluate the geothermal reservoir, as well as to optimize the location of possible future resource and/or injection wells, and to develop methods to reduce the cost of geothermal wells. Plans call for drilling to a total depth of approximately 6,000 ft., or to the depth at which it is either indicated from temperature and test flow data and from logs that an acceptable hot water resource is available or that the hole is accepted as a possible reinjection well. (LBS) Title: Drilling plan: Raft River Geothermal Exploratory Hole No. 3 Author: Industrial Applications Division , Nevada Operations Office Year: 1976 The program, plans, and procedures to be used in drilling and completion of the Raft River Geothermal Exploratory Hole No. 3(RRGE-3) are described. RRGE-3 will be located in the Raft River valley of south central Idaho, southeast of Burley, and approximately 16 miles south of Malta, Idaho. The third exploratory hole will be drilled to provide data to further investigate and evaluate the geothermal reservoir, as well as to optimize the location of possible future resource and/or injection wells, and to develop methods to reduce the cost of geothermal wells. Plans call for drilling to a total depth of approximately 6,000 ft., or to the depth at which it is either indicated from temperature and test flow data and from logs that an acceptable hot water resource is available or that the hole is accepted as a possible reinjection well. (LBS) Close

• 144. [Image] Dipole-Dipole Resistivity Survey of a Portion of the Coso Hot Springs KGRA, Inyo County, California

  	A detailed electrical resistivity survey of 54 line-km was completed at the Coso Hot Springs KGRA in September 1977. This survey has defined a bedrock resistivity low at least 4 sq mi (10 sq km) in extent ...
  	Citation × Citation Citation Abstract Copy Title: Dipole-Dipole Resistivity Survey of a Portion of the Coso Hot Springs KGRA, Inyo County, California Author: Fox, R.C. Year: 1978 A detailed electrical resistivity survey of 54 line-km was completed at the Coso Hot Springs KGRA in September 1977. This survey has defined a bedrock resistivity low at least 4 sq mi (10 sq km) in extent associated with the geothermal system at Coso. The boundaries of this low are generally well defined to the north and west but not as well to the south where an approximate southern limit has been determined. The bedrock resistivity low merges with an observed resistivity low over gravel fill east of Coso Hot Springs. A complex horizontal and vertical resistivity structure of the surveyed area has been defined which precludes the use of layered-earth or two-dimensional interpretive models for much of the surveyed area. In general the survey data indicate that a 10 to 20 ohm-meter zone extends from near surface to a depth greater than 750 meters within the geothermal system. This zone is bordered to the north and west by bedrock resistivities greater than 200 ohm-meters and to the south by bedrock resistivities greater than 50 ohm-meters. A combination of observed increases in: (1) fracture density (higher permeability), (2) alteration (high clay content), and (3) temperatures (higher dissolved solid content of ground water) within the bedrock low explain its presence Title: Dipole-Dipole Resistivity Survey of a Portion of the Coso Hot Springs KGRA, Inyo County, California Author: Fox, R.C. Year: 1978 A detailed electrical resistivity survey of 54 line-km was completed at the Coso Hot Springs KGRA in September 1977. This survey has defined a bedrock resistivity low at least 4 sq mi (10 sq km) in extent associated with the geothermal system at Coso. The boundaries of this low are generally well defined to the north and west but not as well to the south where an approximate southern limit has been determined. The bedrock resistivity low merges with an observed resistivity low over gravel fill east of Coso Hot Springs. A complex horizontal and vertical resistivity structure of the surveyed area has been defined which precludes the use of layered-earth or two-dimensional interpretive models for much of the surveyed area. In general the survey data indicate that a 10 to 20 ohm-meter zone extends from near surface to a depth greater than 750 meters within the geothermal system. This zone is bordered to the north and west by bedrock resistivities greater than 200 ohm-meters and to the south by bedrock resistivities greater than 50 ohm-meters. A combination of observed increases in: (1) fracture density (higher permeability), (2) alteration (high clay content), and (3) temperatures (higher dissolved solid content of ground water) within the bedrock low explain its presence Close

• 145. [Image] Geothermal Resource and Reservoir Investigations of U. S. Bureau of Reclamation Leaseholds at East Mesa, Imperial Valley, California

  	The study included five parts: geology, seismicity, well testing, reservoir simulation, and geochemistry. Included in appendices are: production test data and discussion, interference tests, production ...
  	Citation × Citation Citation Abstract Copy Title: Geothermal Resource and Reservoir Investigations of U. S. Bureau of Reclamation Leaseholds at East Mesa, Imperial Valley, California Author: Howard, J. Year: 1978 The study included five parts: geology, seismicity, well testing, reservoir simulation, and geochemistry. Included in appendices are: production test data and discussion, interference tests, production tests in the northern portion of the East Mesa KGRA, conversion tables, chemical analysis of fluids from East Mesa wells, and results of laboratory studies of scale samples taken from the vertical tube evaporator. (MHR) Title: Geothermal Resource and Reservoir Investigations of U. S. Bureau of Reclamation Leaseholds at East Mesa, Imperial Valley, California Author: Howard, J. Year: 1978 The study included five parts: geology, seismicity, well testing, reservoir simulation, and geochemistry. Included in appendices are: production test data and discussion, interference tests, production tests in the northern portion of the East Mesa KGRA, conversion tables, chemical analysis of fluids from East Mesa wells, and results of laboratory studies of scale samples taken from the vertical tube evaporator. (MHR) Close

• 146. [Image] Low -Altitude Aeromagnetic Survey of a Portion of the Coso Hot Springs KGRA, Inyo County, California

  	A detailed low-altitude aeromagnetic survey of 576 line-mi (927 line-km) was completed over a portion of the Coso Hot Springs KGRA in September 1977. The survey has defined a pronounced magnetic low that ...
  	Citation × Citation Citation Abstract Copy Title: Low -Altitude Aeromagnetic Survey of a Portion of the Coso Hot Springs KGRA, Inyo County, California Author: Fox, R.C. Year: 1978 A detailed low-altitude aeromagnetic survey of 576 line-mi (927 line-km) was completed over a portion of the Coso Hot Springs KGRA in September 1977. The survey has defined a pronounced magnetic low that could help delineate the geothermal system. The magnetic low has an areal extent of approximately 10 C' sq mi (26 sq km). Direct and indirect evidence indicates that this anomaly is due, in part, to magnetite destruction by hydrothermal solutions associated with the geothermal system. The anomaly generally coincides with two other geophysical anomalies which are directly associated with the system: 1) a bedrock electrical resistivity low, and 2) an area of relatively high near-surface temperatures. The highest measured heat flow, 18 HFU, also occurs within its boundary. The magnetic low occurs at the intersection of two major structural zones which coincide with a complementary set of strike-slip fault zones determined from seismic activity. The intersection of these two zones of active tectonism probably served as the locus for emplacement of a pluton at depth, above which are observed the coincidental geophysical anomalies and surface manifestations related to the geothermal system Title: Low -Altitude Aeromagnetic Survey of a Portion of the Coso Hot Springs KGRA, Inyo County, California Author: Fox, R.C. Year: 1978 A detailed low-altitude aeromagnetic survey of 576 line-mi (927 line-km) was completed over a portion of the Coso Hot Springs KGRA in September 1977. The survey has defined a pronounced magnetic low that could help delineate the geothermal system. The magnetic low has an areal extent of approximately 10 C' sq mi (26 sq km). Direct and indirect evidence indicates that this anomaly is due, in part, to magnetite destruction by hydrothermal solutions associated with the geothermal system. The anomaly generally coincides with two other geophysical anomalies which are directly associated with the system: 1) a bedrock electrical resistivity low, and 2) an area of relatively high near-surface temperatures. The highest measured heat flow, 18 HFU, also occurs within its boundary. The magnetic low occurs at the intersection of two major structural zones which coincide with a complementary set of strike-slip fault zones determined from seismic activity. The intersection of these two zones of active tectonism probably served as the locus for emplacement of a pluton at depth, above which are observed the coincidental geophysical anomalies and surface manifestations related to the geothermal system Close

• 147. [Image] Geopressured Energy Resource Evaluation

  	The geopressured aquifers that extend along the northern Gulf of Mexico are a large, perhaps the largest, potential source of geothermal energy and natural gas in the US. Because of the high cost of completing ...
  	Citation × Citation Citation Abstract Copy Title: Geopressured Energy Resource Evaluation Author: Samuels, G. Year: 1979 The geopressured aquifers that extend along the northern Gulf of Mexico are a large, perhaps the largest, potential source of geothermal energy and natural gas in the US. Because of the high cost of completing wells into these formations and their relatively low temperatures (200 to 400 F), the utilization of the geothermal energy will be highly depend on, and of secondary importance to, the value of the methane. The economics of extracting either the geothermal energy or natural gas from these aquifers does not look promising. The combined requirements of high well flow rates (40,000 bbl/day), long life (20 years), and the necessity for close well spacing to minimize the cost of the collection system may be incompatible with the actual characteristics of the reservoirs. These factors place such stringent requirements on the reservoir size, permeability, and compressibility, or specific storage coefficient, that the number of promising production areas may be severely limited Title: Geopressured Energy Resource Evaluation Author: Samuels, G. Year: 1979 The geopressured aquifers that extend along the northern Gulf of Mexico are a large, perhaps the largest, potential source of geothermal energy and natural gas in the US. Because of the high cost of completing wells into these formations and their relatively low temperatures (200 to 400 F), the utilization of the geothermal energy will be highly depend on, and of secondary importance to, the value of the methane. The economics of extracting either the geothermal energy or natural gas from these aquifers does not look promising. The combined requirements of high well flow rates (40,000 bbl/day), long life (20 years), and the necessity for close well spacing to minimize the cost of the collection system may be incompatible with the actual characteristics of the reservoirs. These factors place such stringent requirements on the reservoir size, permeability, and compressibility, or specific storage coefficient, that the number of promising production areas may be severely limited Close

• 148. [Image] Geothermal Resources, Vicksburg Formation, Texas Gulf Coast

  	The potential for discovering geopressured geothermal reservoirs in the Vicksburg Formation is limited to Hidalgo County along the Lower Texas Gulf Coast. In Hidalgo County, an area of approximately 385 ...
  	Citation × Citation Citation Abstract Copy Title: Geothermal Resources, Vicksburg Formation, Texas Gulf Coast Author: Loucks, R.G. Year: 1978 The potential for discovering geopressured geothermal reservoirs in the Vicksburg Formation is limited to Hidalgo County along the Lower Texas Gulf Coast. In Hidalgo County, an area of approximately 385 square miles (designated the Vicksburg Fairway) contains up to 1,300 feet of geopressured sandstones with fluid temperatures greater than 300/sup 0/F. In-place effective permeability, however, averages less than 1 millidarcy in the Vicksburg sandstones because of fine grain size and extensive late carbonate cementation. Also, areal extent of individual reservoirs is limited in a dip direction by growth faults and in a strike direction by the lenticular morphology of the sandstone bodies. In conclusion, under the present specifications set for a geothermal fairway, the Vicksburg has minimal potential because of low reservoir deliverability, which is constrained by low permeability and somewhat limited reservoir continuity. If future tests indicate that lower permeabilities are acceptable, the Vicksburg Fairway should be reconsidered because of the presence of extremely thick sandstone bodies Title: Geothermal Resources, Vicksburg Formation, Texas Gulf Coast Author: Loucks, R.G. Year: 1978 The potential for discovering geopressured geothermal reservoirs in the Vicksburg Formation is limited to Hidalgo County along the Lower Texas Gulf Coast. In Hidalgo County, an area of approximately 385 square miles (designated the Vicksburg Fairway) contains up to 1,300 feet of geopressured sandstones with fluid temperatures greater than 300/sup 0/F. In-place effective permeability, however, averages less than 1 millidarcy in the Vicksburg sandstones because of fine grain size and extensive late carbonate cementation. Also, areal extent of individual reservoirs is limited in a dip direction by growth faults and in a strike direction by the lenticular morphology of the sandstone bodies. In conclusion, under the present specifications set for a geothermal fairway, the Vicksburg has minimal potential because of low reservoir deliverability, which is constrained by low permeability and somewhat limited reservoir continuity. If future tests indicate that lower permeabilities are acceptable, the Vicksburg Fairway should be reconsidered because of the presence of extremely thick sandstone bodies Close

• 149. [Image] Site-Specific Analysis of Hybrid Geothermal / Fossil Power Plants Volume One: Roosevelt Hot Springs KGRA

  	The economics of a particular hybrid plant must be evaluated with respect to a specific site. This volume focuses on the Roosevelt Hot Springs KGRA. The temperature, pressure, and flow rate data given ...
  	Citation × Citation Citation Abstract Copy Title: Site-Specific Analysis of Hybrid Geothermal / Fossil Power Plants Volume One: Roosevelt Hot Springs KGRA Author: Burbank City Public Service Dept., CA (USA) Year: 1977 The economics of a particular hybrid plant must be evaluated with respect to a specific site. This volume focuses on the Roosevelt Hot Springs KGRA. The temperature, pressure, and flow rate data given suggests the site deserves serious consideration for a hybrid plant. Key siting considerations which must be addressed before an economic judgment can be attempted are presented as follows: the availability, quality, and cost of coal; the availability of water; and the availability of transmission. Seismological and climate factors are presented Title: Site-Specific Analysis of Hybrid Geothermal / Fossil Power Plants Volume One: Roosevelt Hot Springs KGRA Author: Burbank City Public Service Dept., CA (USA) Year: 1977 The economics of a particular hybrid plant must be evaluated with respect to a specific site. This volume focuses on the Roosevelt Hot Springs KGRA. The temperature, pressure, and flow rate data given suggests the site deserves serious consideration for a hybrid plant. Key siting considerations which must be addressed before an economic judgment can be attempted are presented as follows: the availability, quality, and cost of coal; the availability of water; and the availability of transmission. Seismological and climate factors are presented Close

• 150. [Image] Transient well testing in two-phase geothermal reservoirs

  	A study of well test analysis techniques in two-phase geothermal reservoirs has been conducted using a three-dimensional, two-phase, wellbore and reservoir simulation model. Well tests from Cerro Prieto ...
  	Citation × Citation Citation Abstract Copy Title: Transient well testing in two-phase geothermal reservoirs Author: Aydelotte, S.R. Year: 1980 A study of well test analysis techniques in two-phase geothermal reservoirs has been conducted using a three-dimensional, two-phase, wellbore and reservoir simulation model. Well tests from Cerro Prieto and the Hawaiian Geothermal project have been history matched. Using these well tests as a base, the influence of reservoir permeability, porosity, thickness, and heat capacity, along with flow rate and fracturing were studied. Single and two-phase transient well test equations were used to analyze these tests with poor results due to rapidly changing fluid properties and inability to calculate the flowing steam saturation in the reservoir. The injection of cold water into the reservoir does give good data from which formation properties can be calculated. Title: Transient well testing in two-phase geothermal reservoirs Author: Aydelotte, S.R. Year: 1980 A study of well test analysis techniques in two-phase geothermal reservoirs has been conducted using a three-dimensional, two-phase, wellbore and reservoir simulation model. Well tests from Cerro Prieto and the Hawaiian Geothermal project have been history matched. Using these well tests as a base, the influence of reservoir permeability, porosity, thickness, and heat capacity, along with flow rate and fracturing were studied. Single and two-phase transient well test equations were used to analyze these tests with poor results due to rapidly changing fluid properties and inability to calculate the flowing steam saturation in the reservoir. The injection of cold water into the reservoir does give good data from which formation properties can be calculated. Close