Cuttings Analysis At Coso Geothermal Area (1985-1987)

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Exploration Activity: Cuttings Analysis At Coso Geothermal Area (1985-1987)

Exploration Activity Details
Location Coso Geothermal Area
Exploration Technique Cuttings Analysis
Activity Date 1985 - 1987

Usefulness useful
DOE-funding Unknown

Exploration Basis
Analyze an indicator of high permeability zones within a geothermal field
Petrographic and geochemical analyses of cuttings from six wells in the Coso Hot Springs geothermal field show a systematic variation in the occurrence, texture, and composition of sericite that can be correlated with high permeability production zones and temperature. The wells studied intersect rhyolitic dikes and sills in the fractured granitic and dioritic basement rocks which serve as the reservoir for the geothermal system. Low-permeability non-productive zones in the wells contain coarse-grained compositionally homogeneous primary muscovite. High-permeability production zones are characterized by abundant fine-grained hydrothermal sericite that exhibits a systematic increase in K and Al and decrease in Si with increasing temperature. These calculations suggest that hydrothermal sericites are in local equilibrium with the geothermal fluid, but primary muscovites in low permeability zones are metastable.

Additional References