1998 年 20 巻 4 号 p. 275-288
The Ogachi hot dry rock test site in Akita Prefecture is one of three active hot dry rock test sites in the world; the other two sites are the European hot dry rock test site at Soultz in France and the Hijiori hot dry rock test site in Yamagata Prefecture. In 1997, a 48 days circulation test was conducted at the Ogachi hot dry rock test site. In the experiment, 20°C water was injected at the flow rate between 200l/min and 700l/min and 120°C hot water was recovered from a production well. In this paper, this experiment was modeled by TOUGH2 applying a fractured model to an artificially fractured zone and a porous model to a non-fractured zone. The simulation results showed a relatively good match between calculated and measured production flow rates when the skin factor of the production well was -0.5. With this model, some production performances of supposed new production wells were predicted . From the results, it was suggested that a new production well would be better to be drilled apart from the existing injection well to a certain extent and the recovery rate was estimated to be about 20% per new production well.