System and method for coupling geothermal energy storage with coalbed methane extraction in unmineable coalbed

A system for coupling geothermal energy storage with coalbed methane extraction in an unmineable coalbed, comprising:

• a ground heat collection unit configured to collect and convert solar energy and surplus electricity from wind and photovoltaic power generation into high-temperature thermal energy;
• a heat injection and energy storage unit comprising a heat injection device, and an injection well, an extraction well, an artificial heat storage space, an upper covering stratum, and a lower covering stratum that are arranged in a formation, wherein the injection well and the extraction well are spaced apart along a horizontal direction of the formation, and each extend downward to and communicate with a deep gas-bearing unmineable coalbed within the formation;
• a part of the unmineable coalbed between the injection well and the extraction well is reconstructed to form the artificial heat storage space with a permeability of 10-100 mD;
• a tight rock stratum covering an upper side of the unmineable coalbed is the upper covering stratum, while a tight rock stratum covering a lower side of the unmineable coalbed is the lower covering stratum;
• the heat injection device is connected to the ground heat collection unit and the injection well, and is configured to inject, via the injection well, the high-temperature thermal energy obtained by the ground heat collection unit into the artificial heat storage space for storage and desorb adsorbed coalbed methane within the artificial heat storage space into free coalbed methane;
• and
• a cogeneration unit connected to the extraction well and configured to extract and utilize, via the extraction well, the high-temperature thermal energy within the artificial heat storage space for heating or cooling and recycle the free coalbed methane for gas supply and power generation.