Geothermal Prospecting in Utah: a new thermal model of the Black Rock Desert

Results from recent geophysical, hydrological, and heat flow projects to assess the geothermal potential of the Black Rock Desert (BRD) in Utah have been combined with historical data to create new 3-dimensional conductive and convective heat transfer models using a finite-element modeling program (COMSOL Multiphysics 4.3b). The insulating effect of thick (up to 3 km), low thermal-conductivity sediments along with typical Basin and Range heat-flow values (80 to 90 mW/m^2) in this deep basin result in higher temperatures at relatively shallow depths compared to surrounding bedrock geotherms. Preliminary models reveal an area of approximately 350 km^2 with temperatures above 150°C at 3 km depth and an inner 60 km^2 area with temperatures above 200°C at the same depth. Temperature at depth and surface heat flow are not evenly distributed throughout the BRD. The relatively low observed surface heat flow and temperatures at depth in the southern BRD may be a consequence of local groundwater flushing over the regional background heat-flow. An extremely localized, high-heat flow area situated in the central BRD is thought to be associated with the more recent volcanic activity in the study area. We present new heat transfer models constrained by existing data from the shallow groundwater system, known geothermal gradients, and material properties to explore the extent and character of geothermal potential in the BRD. New thermal models help characterize and enhance understanding of the dynamics of the BRD and other unconventional geothermal systems in the Great Basin.