| Abstract |
The Hot Dry Rock (HDR) electric power generating system, considered a clean energy system because it scarcely generates greenhouse gases such as CO2, would greatly benefit humankind. Since the idea was first proposed at the Los Alamos National Laboratory in 1972, several field tests have been conducted in locations such as Fenton Hill (U.S.A.), Cornwall (U.K.), Soultz (France), Hijiori (Japan), and Ogachi (Japan). Although extensive studies have been performed at these test sites, the HDR electric power generating system is still under investigation due to some technical and economical difficulties. The development of a numerical simulation system, which could be utilized to optimize the resource development and management, is one such technology. This study investigates the possibility of modeling the Hijiori HDR test site with the numerical simulator TOUGH2. Through history matching studies on preliminary short term circulation tests at the Hijiori HDR test site, it is found that the numerical model, coupled with the double porosity model, can simulate the temperature performance at inflow points of production wells in the HDR reservoir. Following history matching studies, long term temperature performances are predicted for both constant production and constant bottom hole flowing pressure cases. These history matching and prediction studies suggest for the Hijiori HDR test site: (1) The permeability between HDR-1 and HDR-2a may be 7.5 times larger than that between HDR-1 and HDR-3; (2) the temperature at the inflow point of F2a-9 in HDR-2a shows maximum decrease, while the temperature at other inflow points does not show a distinct decrease; (3) the temperature decrease at the inflow point is strongly related to injection rates at the injection well and the distance between injection and production wells. |