A geothermal space heating project was recently completed at the Utah State Prison complex at Crystal Hot Springs located near Murray, Utah. The project was initiated in 1978 as a joint U.S. Department of Energy and State of Utah project.

Geologic and geophysical investigations initiated in 1979 consist of surface geologic mapping and aeromagnetic and detailed gravity surveys. This exploration program along with several shallow thermal-gradient holes provided the structural details for a subsequent exploration drilling program.

The exploration drilling program involved deepening an existing well (SF-1) to 500 ft (150 m) and drilling a new hole (USP/TH-1) to 1,000 ft (300 m) to test the extent of the thermal anomaly. Well SF-1 intersected 175°F (79°C) temperatures in a low permeable quartzite, and well USP/TH-1 intersected highly fractured quartzite in the lower section of the well. A temperature reversal was noted in USP/TH-1 below 700 ft (213 m) with a maximum temperature of 175°F (79°C) occurring in the zone from 300 to 700 ft (90 to 215 m).

Flow testing of USP/TH-1 indicated the well would flow at 1,000 gpm with a sustained flow of 400 gpm at a 3.5 psi drawdown over the heating season. Testing also indicated interference with other nearby wells and thermal springs.

Fluid production for space heating of the prison facilities took place during the winter of 1983-84. This production will give more data to refine the calculations of reservoir producibility and provide information on the economics of utilizing geothermal fluids for space heating.

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