Desert Peak: A Geothermal Field in Churchill County, Nevada

Abstract

The 400'F liquid dominated Desert Peak geothermal reservoir produces from fractures associated with intersecting north-northeast and east-northeast trending normal faults. Fractures occur in intrusive basement rocks, pre-Tertiary metasedimentary and metavolcanic rocks, and Tertiary volcanic rocks. Static temperature surveys from six deep wells indic at e that the reservoir has both recharge and discharge in the vicinity of wells B21-1 and 86-21. Interference data, from a 30-day flow test of 86-21 show high reservoir connectivity. The calculated transmissivity is an order of magnitude higher in a north-south direction than in an east-west direction. A reservoir thickness on the order of thousands of feet and disturbed reserves in excess of 7 billion barrels are estimated. A conceptual model of the Desert Peak system contains meteoric water derived from the Carson and Fernley Sinks. Heated at depth, water rises up along normal faults into highly fractured rocks between the depths of 3000 and 9000 feet, forming a geothermal r e servoir. The thermal water naturally rises or leaks out of the reservoir up normal fault s to within a few hundred feet of the surface until it has reached hydrostatic equilibrium or is blocked by discontinuous impermeable lacustrine sedimentary rocks. In the latter case it spreads out laterally creating a huge near surface thermal anomaly.