Hydrogen chloride in superheated steam and chloride in deep brine at The Geysers geothermal field, California
Chloride (Cl) concentrations of 10-120 ppm{sub w} have been measured in superheated steam produced by wells at The Geysers, a vapor-dominated geothermal field in northern California. Corrosion of the well casing and steam-gathering system has been recognized in some parts of The Geysers, and is apparently related to the presence of Cl. Cl in the steam is in a volatile form, generated with the steam at reservoir temperatures, and probably travels to the wellhead as HCl gas. Published experimental data for partial pressures of HCl in steam over aqueous HCl solutions and for dissociation constants of HCl were used to calculate distribution coefficients for HCl. Reservoir liquid Cl concentrations capable of generating steam with the observed Cl concentrations were then calculated as a function of pH and temperatures from 250 to 350º C. Equilibrium mineral/liquid reactions with the K-mica and K-feldspar assemblage found in the wells limit the reservoir liquid pH values at various Cl concentrations to about 5 to 6 (near neutral at 250 to 350º C). Within this pH range, liquid at 250º C could not produce steam containing the high Cl concentrations observed. However, liquid at higher temperatures (300 to 350º C) with chloride concentrations greater than 10,000 ppm{sub w} could generate steam with 10 to over 200 ppm{sub w} Cl. There is a positive correlation between pH and the chloride concentrations required to generate a given Cl concentration in steam. The concentration of Cl in superheated steam constrains not only the reservoir liquid composition, but the temperature at which the steam last equilibrated with liquid.
- Research Organization:
- GEO Operator Corp., Santa Rose, CA; US Geological Survey, Menlo Park, CA
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AS07-84ID12529
- OSTI ID:
- 887148
- Report Number(s):
- SGP-TR-113-13
- Resource Relation:
- Conference: Proceedings, thirteenth workshop on geothermal reservoir engineering, Stanford University, Stanford, CA, January 19-21, 1988
- Country of Publication:
- United States
- Language:
- English
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