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 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.
- Research Organization:
- Utah Univ., Salt Lake City (USA). Research Inst.
- DOE Contract Number:
- EG-78-C-07-1701
- OSTI ID:
- 6290628
- Report Number(s):
- IDO-1701-2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CALIFORNIA
GEOLOGY
GEOTHERMAL FIELDS
EXPLORATORY WELLS
WELL LOGGING
GEOLOGICAL SURVEYS
GEOPHYSICAL SURVEYS
HOT-WATER SYSTEMS
CALIPER LOGGING
GAMMA LOGGING
GEOCHEMISTRY
GEOTHERMAL GRADIENTS
HEAT FLOW
HYDROTHERMAL ALTERATION
INDUCTION LOGGING
KGRA
MAPS
NEUTRON LOGGING
POROSITY
RESISTIVITY LOGGING
SONIC LOGGING
SP LOGGING
TEMPERATURE LOGGING
WELL COMPLETION
WELL DRILLING
CHEMISTRY
DRILLING
ELECTRIC LOGGING
GEOTHERMAL SYSTEMS
HYDROTHERMAL SYSTEMS
NORTH AMERICA
RADIOACTIVITY LOGGING
TEMPERATURE GRADIENTS
USA
WELLS
WESTERN REGION
Geothermal Legacy
150303* - Geothermal Exploration & Exploration Technology- Exploratory Drilling & Well Logging
150301 - Geothermal Exploration & Exploration Technology- Geophysical Techniques & Surveys
150302 - Geothermal Exploration & Exploration Technology- Geochemical Techniques & Surveys