Long-Term Circulation Test at Hijiori Site, Japan

Abstract

The New Energy and Industrial Technology Development Organization (NEDO) is conducting research on development of hot dry rock (HDR), a future geothermal resource. A small heat extraction system for HDR was constructed in a geothermal area, Hijiori. To verify the heat extraction capacity of these artificial HDR geothermal reservoirs, a long-term heat extraction experiment was planned and is now being conducted. The test commenced last November and was successfully continued over 240 days to the end of July. Maximum thermal output was 9.3 MWt in the early part of the circulation test when recovery was over 60%. These figures had decreased to 5MW and 42%, respectively, by the end of July. Thermal output and surveyed temperature profile data provided clear thermal draw down of the production zones in HDR-2a. The model of the Hijiori system can be reevaluated with this data and will be used in the verification.