Update on the Raft River Geothermal Reservoir

Abstract

Since the last conference, a fourth well has been drilled to an intermediate depth and tested as a production well, with plans to use this well in the long term for injection of fluids into the strata above the production strata. The third, triple legged well has been fully pump tested, and the recovery of the second well from an injection well back to production status has revealed very interesting data on the reservoir conditions around that well.

Both interference testing and geochemistry analysis shows that the third well is producing from a different aquifer than that supplying the No. 2 well. There is an effective barrier, yet unidentified as to structure, making pressure communication between these aquifers quite negligible. These results have led to significantly different models for the aquifer system than those previously believed to apply.

THE 4-WELL SYSTEM
The Raft River Geothermal Program now has 3 deep production wells, with producing zones between 3750 and 6000 ft. recently drilled for injection testing into the zone between 1850 and 2500 ft. Figure 1 shows the location of the wells with respect to the major faults in the region. Figure 2 shows cross sections of each well. Additional details on these wells may be found in Reference l ( last year's conference).