Analysis of long-term performance of hot dry rock geothermal energy extraction systems based on fractal fracture network model

Based on a fractal fracture network model of a Hot Dry Rock geothermal reservoir, a numerical analysis of hydraulic stimulation and heat extraction was carried out. Ogachi field, a demonstration field of Hot Dry Rock geothermal energy extraction system, was chosen for the analysis. The hydraulic stimulation to create a two-layer reservoir was simulated numerically, and it became clear that fracture orientation has significant influence on the direction of the stimulated area, i.e., the reservoir direction. Using the fracture patterns chosen by temperature history matching of a 150 days circulation test, the long-term profile of production temperature at Ogachi was estimated. Although there are some assumption for water flow in the reservoir, the production temperature was estimated to be 150°C after 10 years.