Use of Slim Holes for Geothermal Reservoir Assessment: An Update

Abstract

Production and injection data from slim holes and large-diameter wells in three (3) geothermal fields (Oguni, Steamboat Hills) were examined to determine the effect of borehole diameter (1) on the discharge rate and (2) on the indices. For boreholes with liquid feedzones, maximum discharge rates scale with diameter according relationship derived by The latter rule does not apply to discharge data for boreholes with twophase feedzones. Data from Oguni and Sumikawa geothermal fields indicate that the productivity (for boreholes with liquid feeds) and injectivity indices are more or less equal. The indices for boreholes are essentially independent of borehole diameter. The latter result at variance with Oguni data; both the productivity and injectivity indices for Oguni boreholes display a strong variation with borehole diameter. Based on the discharge and injection data these three geothermal fields, the flow rate of large-diameter production wells with liquid feedzones canbe predicted using data from slim holes.