Application of acid fracturing technology to improve water yield of deep carbonate geothermal wells

To achieve the “carbon peak” goal, green and low-carbon energy development is the key. As one of the five non-carbon-based energy sources, geothermal energy is significant to achieving the dual carbon goal. Hydrothermal geothermal resources are very abundant in China, and carbonate rock thermal reservoirs are the main battlefield for the development of hydrothermal geothermal resources. At present, the geothermal energy industry has initially formed in China. Xiong’an New Area is the area with the best conditions for the development and utilization of geothermal resources in the central and eastern parts of China, and the carbonate thermal reservoir is the main geothermal development and utilization layer in Xiong’an New Area. Based on the principle of chemical reaction between hydrochloric acid and the main components of carbonate rock, calcite CaCO₃ and dolomite CaMg （CO₃）₂, four rock samples from geothermal wells were dissolved with 15% and 20% hydrochloric acid, respectively. The comparison showed that 15% hydrochloric acid was more economical and effective. The percolation capacity of acid dissolution fractures was tested through percolation capacity experiments, and the optimal amount of acid solution was determined to be 2-8 PV. It was verified that acid dissolution helps improve fracture percolation capacity. Through the on-site testing of acid fracturing technology in the Xiong’an New Area, it has been verified that the on-site implementation of multi-stage acid fracturing has a significant effect on increasing production. Finally, conclusions are drawn. The method of using acid solution dissolution to increase the water yield of deep carbonate geothermal wells is feasible, and the multi-stage acid fracturing technology is suitable for deep wells and can increase the water output of geothermal wells, which has good promotion value.