Direct Detection of Geothermal Reservoir at Hatchobaru Geothermal Field by the Mise-a-la-Masse Measurement

Abstract

The mise a la masse survey was carried out in 1983 at Hatchobaru geothermal field using the HT-8 exploratory well which is located near the known production zone of geothermal resources. The resulting residual maps clearly indicted the four promising low resistivity zones including the present geothermal reservoir which supplies the mixture of steam and to water to the 55 MW power plant. It was found that the measurement gave rise to the sharply contoured residual anomalies because of the high contrast in true resistivity between rocks and the geothermal reservoir at Hatchobaru geothermal field. It was concluded that the strike of faults that regulate the upstream of the geothermal fluid and the lateral distribution of the geothermal reservoir could be directly detected by the mise a la masse measurement at Hatchobaru geothermal field.