Print this pageAbstract: Geology of Salton Sea Geothermal Field
The Salton Sea field in Imperial County, California, covers 46.6 sq km (18 sq mi) south of the Salton Sea. Drilling indicates the presence of 2 × 1018 J (2 × 1015 Btu) of heat contained in 1.3 × 109 M.T. of hot salty water at temperatures above 230°C that could in principle be used to generate 400 MW of electric power for 20 years.
Brines with temperatures of more than 300°C and salinities of more than 30 percent are in fractured sandstone sections of the nonmarine Palm Springs Formation. These lie under a 260-650 m (840-2,130 ft) layer of Pleistocene and Pliocene (?) shale and clay that traps the water and minimizes conductive heat loss. Source of heat is young rhyolitic intrusive rocks in the subsurface and at the surface near the shore of the Salton Sea. Reservoir-fluid temperatures increase with increasing thickness of overlying clay and are modified by variations in permeability caused by original sedimentation and by faulting. Delta, stream, beach, and lacustrine environments can be recognized in the reservoir section.
Measured well flows of 5 × 10-2 to 8 × 10-2 cu m/s (800-1,300 gpm) indicate flow through fractures at an effective reservoir permeability as high as 10-12 sq m (1 darcy).
Structure is dominated by a series of northwest-southeast strike-slip faults with several hundred feet of apparent vertical separation. Variations in thickness and sandstone distribution indicate that these faults were active during deposition, and some are seismically active today.
AAPG Search and Discovery Article #90972©1976 AAPG-SEPM Annual Convention and Exhibition, New Orleans, LA