Analysis of adaptation conditions for CBM separate layer fracturing and multi-layer drainage technologies: a case study of Wubu mining area

The implement of separate layer fracturing and multi-layer drainage in the multiple coal seams is an important method to reduce the costs of exploration and development, and to increase the gas production. There are rich CBM (coalbed methane) resources in Wubu mining area, and S1 and T1 are two major CBM-producing seams. To study the applicability of this technology in Wubu mining area, the influential factors of separate layer fracturing and multi-layer drainage for coal seams S1 and T1 have been analyzed. The feasibility of separate layer fracturing and multi-layer drainage in Wubu mining area is discussed. The result indicates that the pressure gradient and permeability of the coal seams S1 and T1 are similar, but the properties of the roof with backplane and hydrogeological conditions are different, the inter-layer interference exists in the separate layer fracturing and multi-layer drainage process. So the technology of separate layer fracturing and multi-layer drainage is not suitable tor coal seams S1 and T1 in Wubu mining area at present. The early drainage effect of CBM wells in Wubu mining area has verified the reliability of theoretical analysis.