| Description |
A geothermal resource assessment of the Basin and Range Province in western Utah was carried out to identify resource potential for future exploration and exploitation. This assessment includes the following: (1) a new map of background heat flow, generated from approximately 500 new and existing heat flow determinations, (2) surface ground temperature established continuously across the state, and (3) a comprehensive thermal conductivity database compiled with more than 2300 measurements on Utah rock. Finally, a two-dimensional finite difference code was written to integrate determined heat flow, surface temperature, and thermal conductivity to model temperatures at depth. Two cross-sections of the resulting temperature fields are presented from different regions of the Basin and Range. The first, in Utah's Blackrock Desert, was located to assess the highest recorded background heat flow (>130 mWm-2) in the state. The second, along the axis of the Great Salt Lake, was placed in a broad swath of elevated heat flow (>105 mWm-2). Temperatures and heat content of the rock at depths commonly accessed by current drilling technology (3-5 km) were evaluated for each section. In Blackrock Desert, 150 °C was encountered at depths generally greater than 3 km and the thermal potential of rock between 3 km and 4 km for exploitation ranged between 0.14 EJkmand-3 and 0.49 EJkm-3 , with a mean value 0.31 EJkm-3. In the Great Salt Lake Region, the depth to 150 °C is less than 3 km across the basin and the calculated thermal potential, in the 3 km to 4 km depth interval, is between 0.33 EJkm-3 and 0.40 EJkm-3 with a mean 0.37 EJkm-3. High heat flows reported in the Blackrock Desert are encouraging indicators of the region's geothermal potential; however, more complicated geology and the presence of young cooling volcanics and intrusives appears to be inflating heat flow determinations, ultimately exaggerating modeled estimates of regional scale temperatures through basin sediments. In the Great Salt Lake Region, the combination of elevated heat flow, low conductivity sediments, and depth to basement result in temperatures and thermal potential that flag the region as prospective and a priority for geothermal exploration. |
