Geothermal Discovery in the Black Rock Desert of Western Utah

Mark Gwynn, Rick Allis, Robert Blackett, and Christian Hardwick
Utah Geological Survey

The Utah Geological Survey drilled 10 temperature-gradient boreholes in the Black Rock Desert of western Utah in 2011-2012. Seven of these wells and three others drilled in the 1970s show that the background heatflow in the Black Rock Desert is about 80-85 mW/m² and delineate a geothermal resource where temperatures greater than 150°C cover an area of about 350 km² at a depth of 3 km. The resource coincides with the axis of an actively extending basin containing late Tertiary-Quaternary sediments up to 3 km thick overlying Mid-Late Cambrian carbonate bedrock. An area of approximately 60 km² reveals temperatures above 200°C at 3 km depth. An abandoned oil exploration well confirms temperatures of 230°C at 3.3 km depth in the center of the thermal anomaly. The near-surface temperature gradient in the vicinity of this well is 105°C/km and the heat flow is 125 mW/m². The thermal anomaly may be associated with a cooling intrusion in the upper crust beneath Pavant Butte volcano, which last erupted about 15,000 years ago. Potential geothermal reservoirs likely exist in the near-horizontal carbonate strata between 3 and 4 km deep in the Black Rock Desert. These units are exposed in the adjacent Cricket Mountains west of the Black Rock Desert. If these carbonate bedrock formations are sufficiently permeable, a substantial deep geothermal resource may exist in the Black Rock Desert.

AAPG Search and Discovery Article #90169©2013 AAPG Rocky Mountain Section 62^nd Annual Meeting, Salt Lake City, Utah, September 22-24, 2013