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Title: Geological and geophysical analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California

Abstract

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 characcterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the accoustic 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 betweenmore » depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet.« less

Authors:
Publication Date:
Research Org.:
Utah Univ., Salt Lake City (USA). Research Inst.
OSTI Identifier:
5754045
Alternate Identifier(s):
OSTI ID: 5754045
Report Number(s):
IDO-78-1701.b.4.2
DOE Contract Number:  
EG-78-C-07-1701
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; COSO HOT SPRINGS; EXPLORATORY WELLS; GEOTHERMAL WELLS; WELL DRILLING; WELL LOGGING; BOREHOLES; CALIFORNIA; GAMMA LOGGING; GEOLOGIC STRUCTURES; GEOLOGY; GEOTHERMAL GRADIENTS; HEAT FLOW; HOT-WATER SYSTEMS; HYDROTHERMAL ALTERATION; NEUTRON LOGGING; PERMEABILITY; RESERVOIR ROCK; SONIC LOGGING; TEMPERATURE LOGGING; CAVITIES; DRILLING; GEOTHERMAL SYSTEMS; HYDROTHERMAL SYSTEMS; NORTH AMERICA; RADIOACTIVITY LOGGING; ROCKS; TEMPERATURE GRADIENTS; USA; WELLS; WESTERN REGION Geothermal Legacy 150303* -- Geothermal Exploration & Exploration Technology-- Exploratory Drilling & Well Logging

Citation Formats

Galbraith, R.M. Geological and geophysical analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California. United States: N. p., 1978. Web. doi:10.2172/5754045.
Galbraith, R.M. Geological and geophysical analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California. United States. doi:10.2172/5754045.
Galbraith, R.M. Mon . "Geological and geophysical analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California". United States. doi:10.2172/5754045. https://www.osti.gov/servlets/purl/5754045.
@article{osti_5754045,
title = {Geological and geophysical analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California},
author = {Galbraith, R.M.},
abstractNote = {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 characcterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the accoustic 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.},
doi = {10.2172/5754045},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon May 01 00:00:00 EDT 1978},
month = {Mon May 01 00:00:00 EDT 1978}
}

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