Analysis Method of the Occurrence Law of Coalbed Gas Based on Gas-Geology Units: A Case Study of the Guhanshan Mine Field, Jiaozuo Coalfield, China

The correct understanding of the occurrence law of coalbed gas (CBG) is the premise of gas disaster prevention, outburst risk prediction, and gas exploitation. The factors affecting gas occurrence in different gas-geology units are different, so the correct division of gas-geology units is the foundation for studying the occurrence law of CBG. In view of this, this paper defined the division principle of gas-geology units. A gas-geology unit is an area with the same gas-geology characteristics. Based on the division of tectonic units, gas-geology units can be divided by integrating the differences of in situ stress, geological factors, and gas distribution of each tectonic unit. Then, taking the Guhanshan mine field in the Jiaozuo coalfield as an example, the analysis method of the occurrence law of CBG based on gas-geology units was expounded. Taking the EW section, NE section, and their extension lines of the Tuanxiang fault as the boundary, the Guhanshan mine field was divided into four tectonic units, and the factors affecting the gas occurrence of each tectonic unit were analyzed. Finally, according to the difference of the bedrock thickness and the CBG distribution in the four tectonic units, combined with the fracture development degree of the coal seam, surrounding rock, and the development degree of deformed coal, the Guhanshan mine field was divided into three gas-geology units, and their occurrence law of CBG was analyzed.