NEDO "Deep-seated Geothermal Resources Survey": A Link of Igneous, Metamorphic and Hydrothermal Processes

Abstract

Since FY 1992, NEDO has been conducting the Deep-seated Geothermal Resources Survey to confirm the existence of deep geothermal reservoirs m deep) in basement and/or intrusive rocks beneath the already utilized shallower reservoirs m deep). A primary means of this program, a m class drillhole Wedge-I actually started to be dnlled from early January 1994 at the Kakkonda geothermal field, Northeast Japan. This program also involves mud logging, cuttings and core surveys, various kinds of electrical logging. micro-earthquake activity monitoring, synthetic fluid inclusion, vertical electro-magnetic profiling surveys and flow tests at 3,000 m and 4,000 m depths. The WD-1 has been drilled down to 1,505 m until May 1994 and the result is briefly summarized in this paper. Before completing this program in FY 1997, the may reach a rim of the neo-granitoid pluton at about 3,000 m depth in FY 1995 and may reach about 400 at m depth in FY 1996. Nature of the plutonic reservoir and several other scientific objectives are expected to be clarified in the remaining course of this program.