Simulation of Hydraulical Fracture for Hot Dry Rock

Abstract

The Japanese hot dry rock project started at Yakedake field in the Gifu Prefecture in 1977. Yakedake field is located 250 km west of Tokyo. This areas has been regarded as a promising geothermal site because it is close to the Yakedake volcano. In 1980 and 1981 five boreholes, HY, S-l, S-2, S-3, and S-4 were drilled to a depth of 300 meters as shown in Figure 1. Two boreholes, HY-2 and. CW were drilled in 1982 and 1983. HY-2 was used for hydraulic fracturing and CW for hydraulic connections. Hydraulic fracturing tests were repeated to get information on fracture direction and radius. The fracture radius was calculated by two different approaches based on the stress balance and heat and mass transfer respectively. The estimated results are compared with the experimental results.