CO₂ Storage and Geothermal Extraction Technology for Deep Coal Mine

This paper aims at reducing greenhouse gas emissions, which contributes to carbon neutrality, and, at the same time, preventing mine heat disasters and extracting highly mineralized (HM) mine water, so as to realize the synergy between CO₂ storage (CS) and geothermal extraction and utilization (GEU) in a high temperature (HT) goaf. With this purpose, an innovative CS-GEU technology for HT and HM water in deep mine is proposed, based on the mechanism of water-rock-CO₂ effect (WRCE) and the principle of GEU in the mine. This technology uses GEU to offset the costs of CO₂ storage and refrigeration in HT mine. A general scheme for a synergistic system of CS and GEU in the goaf is designed. The feasibility of CS-GEU technology in the deep goaf is demonstrated from the views of CS and GEU in the goaf and the principles of a synergistic system. It is clarified that the CO₂ migration-storage evolution and the multi-field coupling principle in the goaf are the key scientific issues in realizing the synergic operation of CS and GEU. It proposes the key techniques involved in this process: CO₂ capture and CO₂ transportation, layout and support of drill holes and high-pressure (HP) pipelines, and HP sealing in the goaf. The research results provide new ideas for CS and GEU of HT and HM mine water in deep mine.