Risk assessment of earthquakes induced during HDR development: A case study in the Gonghe Basin, Qinghai Province, China
Gaofan Yue, Xiaoyuan Li, Wei Zhang
Abstract
Earthquakes induced during hot dry rock (HDR) geothermal development have attracted extensive attention and constrained the further exploitation of HDR resources. Seismic risk evaluation of HDR projects is essential. The first HDR demonstration project in China is located in the Gonghe Basin in Qinghai. The EGS (enhanced geothermal systems) site is located near Gonghe County and is very seismically sensitive. The seismic risk induced by hydraulic fracturing and long-term cycling during the HDR development process was evaluated using a multi-field coupling method based on analysis of the geothermal geological conditions, ground stress, and natural fracture characteristics. During hydraulic fracturing, the predicted magnitude of earthquake events is generally below 2.0, with a range of 0.7–1.3. During a 30-year development period, the predicted maximum earthquake magnitude is less than 1.28. The HDR development will not have an impact on the local geological safety. Considering the uncertainty of the geology, a further discussion of measures to reduce the risk of earthquakes is presented. An entire induced seismic risk evaluation process method is developed, which can provide a reference for related research.