Theoretical basis of dredging and efficient development of high−rank coalbed methane in China: A case study of the Qinshui Basin

China is rich in high-rank coalbed methane(CBM) resources, which accounts for more than 90% of the total production of CBM in China. The efficient development and utilization of high-rank coal and coalbed methane(CBM) resources is of great practical significance for ensuring national energy strategic security and helping to achieve the strategic goals of “carbon peak and carbon neutrality”. The coalbed methane industry in China is generally characterized by low exploration and development degree, poor adaptability of main technology, low rate of return on investment and small development scale. The large-scale and efficient development of coalbed methane is faced with great challenges. Through in-depth analysis of the problems in exploration and development, it is concluded that the core problems restricting the efficient development of coalbed methane industry are all due to the unclear understanding of the characteristics of coal reservoir, especially the occurrence, migration and production of original gas and water, and the lack of matching development theory and supporting engineering technology. Aiming at these problems, the study on the regularity of occurrence and production of CBM water was carried out, and the theory of efficient development of CBM and supporting engineering technology were formed by combining laboratory test with field practice. The results show that: (1) The main factors affecting the efficient development of coalbed methane in China are complicated reservoir forming process, diverse gas reservoir types, strong objective conditions of heterogeneity, insufficient support of top design, and unclear adaptability of main technology; (2) The complex double pore structure of pore-fissure in coal seam and the inherent regularity of gas and water occurrence, production and migration determine that “dredging” and “guiding” must be taken as the leading ideas to realize the full communication between reservoir and wellbore and the efficient production of fluid; (3) Taking high-rank coal in Qinshui Basin as an example, the supporting development technology based on the dredging development theory can effectively realize efficient large-scale construction and production, and significantly improve the development effect of coalbed methane.