Evaluation of Geothermal Characteristics and Fracturing Simulation of Shallow Granite-Type Heat Reservoir

Wide distribution of Meso-cenozoic granite and hot springs indicate that the Wendeng area has rich geothermal resources. In this paper, we investigated the mining potential of Hot Dry Rock (HDR) geothermal resources in the Wendeng area based on the previous drilling, logging and core testing. Thermal extraction simulations were conducted to assess the long-term dynamic productivity based on the fracturing results. A variety of possible well layout patterns and operation parameters were considered. Results indicate that during reservoir stimulation injection volume has a very important effect on created reservoir size. During thermal extraction, pressure indicator is more sensitive to well layout mode than temperature indicator. For the same reservoir, the power generation of the five-spot well mode is slightly improved than that of the triplet-well mode. For naturally fractured formations with stress shielding, large well spacing should be maintained and reservoirs with overdeveloped natural fractures should not be selected. For the reservoir at depth of 4000 m in the Wendeng area, adopting triplet-well mode, the maximum injection rate is 60 kg/s, the power generation over 20-year period is 8.32 MW~1.62 MW, and the energy efficiency ranges from 142.4 to 17.1.