Potential evaluation of coalbed methane resources in western Shouyang County of Qinshui Basin

In view of the current situation of unclear coalbed methane occurrence, low exploration level, and insufficient resource potential evaluation basis in Jingshangdong block in the western region of Shouyang, the following parameters of coal beds were obtained, including burial depth, thickness, structure, coal quality, gas content, isothermal adsorption property, porosity, permeability, reservoir pressure and crustal stress. The occurrence characteristics of coal seam, gas bearing capacity and adsorption characteristics, coal petrology and coal metamorphism, coal reservoir characteristics and resource development potential were studied in this paper. The results show that the cumulative thickness of coal seams in this area is large, the average thickness is 9.91 m, the coal metamorphism is high, and the gas content of each coal seam is high with the average gas content of No.3, 8, 15, 15 lower coal bed at 13.69, 14.29, 9.59 and 11.82 m3/t, respectively. The estimated CBM resources is 145.13×108 m3, suggesting good resource conditions. The gas saturation of coal beds are low, ranging from 40% to 62%, with an average of 50%. The critical desorption pressure ranges from 0.65 MPa to 2.76 MPa with an average value of 1.38 MPa. The average porosity is 4.89%, micro-fractures and macro-fractures have poor connectivity, with a permeability of 4.5×10-17 m2，which is very poor. The closing pressure is large, and the difference between the rupture pressure and the closing pressure is small; low gas saturation, low critical desorption pressure, and low permeability are unfavorable factors for future CBM exploitation. The comprehensive analysis shows that the block has the potential for further exploration and development. The comprehensive analysis shows that the block has the potential for further exploration and development.