Investigation of behavior of engineered geothermal reservoirs by super-resolution mapping techniques

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Geothermal energy is one of the most potential energy source in future, because it is widely distributed on the earth, safe, clean and environmentally friendly to the earth. Engineered geothermal systems, which includes hot dry rock (HDR), hot wet rock (HWR) and enhanced geothermal systems (EGS), are promising for electrical power generation in future. However, behavior of reservoirs associated with hydraulic fracturing has not been clearly understood, and hence this brings uncertainty/risk in the development of engineered geothermal systems. In this project, microseismic techniques for delineation of structures inside the microseismic cloud was investigated, then informations from microseismicity was combined with geological information and rock mechanics to interpret/understand physics in the reservoir. Major results from this project are,1. Data sets collected at Soutls, Fenton-Hill, Rosemanowes, Ogachi, and Hijiori were re-analyzed by super-resolution mapping techniques. Location and orientation of microscopic seismic structures were estimated and their behavior (slip, stress conditions etc.) were also estimated. Variation of super-resolution mapping techniques was investigated to reduce uncertainty/error in mapping.2. Relationship between seismic activity and geological information including location and orientation of preexisting fracture was investigated by tests in laboratory simulating a shear slip of fracture in granite.