A brine interface in the Salton Sea Geothermal System, California: Fluid geochemical and isotopic characteristics
- Univ. of California, Riverside (USA)
Data from 71 geothermal production intervals in 48 wells from the Salton Sea Geothermal System (SSGS) indicate that fluids in that system cluster into two distinct populations in terms of their salinity and their stable isotopic compositions. The distinctive, hot, hypersaline brine (typically >20 wt% total dissolved solids) for which the SSGS is known is overlain by a cooler (<260{degree}C) fluid with distinctly lower salinity (typically <10 wt% total dissolved solids). Hypersaline brines have high and rather consistent {sup 18}O shifts produced by water-rock interaction and have a very narrow range in {delta}D values. Low TDS fluids, on the other hand, show a wide range in both {delta}D and {delta}{sup 18}O. production of both types of fluid from closely spaced geothermal wells in many regions of the SSGS indicates that a relatively sharp salinity interface exists over much of the field. The fluid interface typically cross-cuts sedimentary bedding but is consistently found where reservoir temperatures are approximately 260{degree}C. At these temperatures, hypersaline brines have densities of approximately 1.0 gm/cm{sup 3}, while the low TDS fluids have densities as low as 0.85 gm/cm{sup 3}. This stable, density-stratified interface acts as a barrier to convective heat and mass transfer in the SSGS, isolating the hypersaline reservoir from overlying dilute fluids. A lithologic cap implied by previous SSGS models is unnecessary in such a stratified system since heat and mass transfer across the interface must occur by slow conductive, diffusional and interface mixing processes regardless of local permeability.
- OSTI ID:
- 7170890
- Journal Information:
- Geochimica et Cosmochimica Acta; (USA), Vol. 53:8; ISSN 0016-7037
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
BRINES
GEOCHEMISTRY
ISOTOPE RATIO
ROCK-FLUID INTERACTIONS
SALTON SEA GEOTHERMAL FIELD
CALIFORNIA
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
GEOTHERMAL FLUIDS
GEOTHERMAL WELLS
WATER CHEMISTRY
CHEMISTRY
FEDERAL REGION IX
FLUIDS
GEOTHERMAL FIELDS
NORTH AMERICA
USA
WELLS
152001* - Geothermal Data & Theory- Properties of Aqueous Solutions
580000 - Geosciences