Hydrothermal Control by Deep Hidden Faults on Geothermal Systems in Sedimentary Basins: A Case Study of the Cangdong Fault in the North China Basin

Abstract

Large basins are currently the global focus for geothermal development, with their hydrothermal system being controlled by a variety of factors, such as basement relief and fracture development. Donglihu is located at the north of the Cangxian uplift in the North China Basin, the concentrated geothermal resource development zone in North China. This study systematically collects temperature logging data and long-term dynamic monitoring of water level and water quality as well as group well tracer test data carried out in this area in recent years, on the basis of which the hydrothermal controlling role of the deep hidden faults is systematically analyzed. The results show that the Cangdong fault communicates with different geothermal reservoirs in the shallow part and plays a specific role in the water-heat channel of the local area. As a result, the high-value area of the geothermal temperature gradient in the sedimentary layer of the Donglihu area is distributed around the Cangdong fault. The geothermal reservoir temperature of the Minghuazhen Formation within the influence of the fault is also significantly higher than the regional average, the hydraulic head of different geothermal reservoirs showing a consistent and synergistic trend. However, the water quality has been stable for many years without any apparent changes. This understanding has a particular significance for further deepening understanding of the geothermal genesis mechanism in sedimentary basins and guiding future geothermal exploration and development in the Donglihu area.