Chemical and isotopic studies of the Coso geothermal area

Conference · Fri Jan 01 04:00:00 EST 1982

OSTI ID:7369548

Fournier, R O; Thompson, J M

Wellhead and downhole water samples were collected and analyzed from a 114.3-m well at Coso Hot Springs (Coso No. 1) and a 1477-m well (CGEH No. 1) 3.2 km to the west. The same chloride concentration is present in hot waters entering both wells (about 2350 mg/kg), indicating that a hot-water-dominated geothermal system is present. The maximum measured temperatures are 142/sup 0/C in the Coso No. 1 well and 195/sup 0/C in the CGEH No. 1 well. Cation and sulfate isotope geothermometers indicate that the reservoir feeding water to the Coso Hot Spring well has a temperature of about 240 to 250/sup 0/C, and the reservoir feeding the CGEH well has a temperature of about 205/sup 0/C. The variation in the chemical composition of water from the two wells suggests a model in which water-rock chemical equilibrium is maintained as a convecting solution cools from about 245 to 205/sup 0/C by conductive heat loss. A total of 39 water samples collected from the Coso geothermal area and vicinity and were analyzed for major chemical constituents, delta D and delta/sup 18/O. Nonthermal ground waters from the Coso Range were found to be isotopically heavier than those from the Sierra Nevada to the west. The similarity of the delta D value for the deep thermal water at Coso to that of the Sierra water suggests that the major recharge for the hydrothermal system comes from the Sierra Nevada rather than from local precipitation on the Coso Range.

• Research Organization: Geological Survey, Menlo Park, CA
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7369548
• Report Number(s): SGP-TR-60; CONF-821214-7; ON: DE83015865
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150302* -- Geothermal Exploration & Exploration Technology-- Geochemical Techniques & Surveys
CALIFORNIA
CHEMICAL COMPOSITION
COSO HOT SPRINGS
ENERGY SYSTEMS
FEDERAL REGION IX
GEOCHEMICAL SURVEYS
GEOTHERMAL SYSTEMS
GEOTHERMAL WELLS
GEOTHERMOMETERS
Geothermal Legacy
HYDROTHERMAL SYSTEMS
ISOTOPE EFFECTS
KGRA
MEASURING INSTRUMENTS
NORTH AMERICA
OXYGEN COMPOUNDS
RECHARGE
ROCK-FLUID INTERACTIONS
SAMPLING
SULFATES
SULFUR COMPOUNDS
SURVEYS
THERMAL WATERS
THERMOMETERS
USA
WELLS