Electricity generation from a three-horizontal-well enhanced geothermal system in the Qiabuqia geothermal field, China: Slickwater fracturing treatments for different reservoir scenarios

Hot dry rock (HDR), as a clean renewable energy source, can help fulfill future energy needs and reduce the greenhouse effect. This energy source in the Qiabuqia geothermal field of Northwest China is expected to generate electricity. In this study, we used the lab parameters and the GR1 well data from the Qiabuqia site to numerically investigate the reservoir stimulation and electricity generation from a three-horizontal-well EGS system created in the granitic reservoir at depth 3500–3700 m, and at an average temperature of 218 °C. Slickwater fracturing and the resulting reservoir scenarios for different expected conditions in the region were analyzed in order to find suitable fracturing strategies. We then proposed three optimized EGS scenarios and evaluated their economic and environmental benefits. Results indicate that EGS power generation significantly depends on the reservoir stimulation results. The potential 2.61–4.90 MW installed capacity and 433.72–913.05 GWh total power generation are expected to be realized if the well spacing of 300–500 m and the hot water circulation rate of 20–40 kg/s in a 20-year period are achieved via the slickwater fracturing treatment. The final production temperature can be maintained at approximately 200 °C, and the corresponding temperature drops less than 10%. Such a case of geothermal engineering is expected to result in a reduction in greenhouse gas (GHG) emissions of 0.15–1.1 Mt, and its levelized cost of energy (LCOE) is estimated at 0.047–0.066 $/kWh.