Validation of Play Fairway Analysis of the geothermal potential of Camas Prairie, south-central Idaho, by an exploration well

Play Fairway Analysis (PFA) methodology was adapted for geothermal exploration at Camas Prairie, Idaho. Geophysical data, structural and geologic mapping, volcanic rock ages and vent locations, and the distribution of thermal springs and wells all indicated a relatively high geothermal potential along the southern margin of the Prairie. An exploration well (USU Camas-1) was drilled to a depth of 618.3 m to validate the PFA. A permeable zone was encountered at similar to 357.5 m with a maximum measured temperature of similar to 80 degrees C, which was suppressed following the injection of cold water. A moderate transmissivity of similar to 0.25-1 cm(2)/s estimated from an injection test as well a seasonal artesian flow at similar to 0.7 L/s corroborate the presence of a permeable zone. The existence of a lacustrine clay seal was confirmed near the bottom of the basin-fill sediment occupying the upper 314 m of the well. Geothermometers suggest the USU Camas-1 well water equilibrated at a reservoir temperature of similar to 120 degrees C. Based on the locations of both thermal and cold wells, geothermal fluids appear to be flowing upward along one or both of two fault systems. The presence of young basalts and elevated helium isotope ratios suggest that the heat source of Camas Prairie is magmatic. However, the faults may be acting as a conduit for geothermal fluids to rise from great depth without a shallow magmatic source being present. Camas Prairie is a promising area for geothermal development, but the relatively low reservoir temperatures indicate this resource may not be suitable for electric generation. Perhaps the best use would be for heating.

Automated summary

The Play Fairway Analysis (PFA) methodology was used to assess the geothermal potential of Camas Prairie in Idaho. Geophysical data and geological mapping confirmed the presence of a high geothermal potential along the southern margin of the Prairie. A drilling well was conducted, encountering a permeable zone at a depth of 357.5 m and confirming the presence of geothermal fluids flowing upward along fault systems.