the development of coalbed methane in China is mainly concentrated in areas with coal seam depth less than 1200 m, and no substantial breakthrough has been made in deep coalbed methane with burial depth greater than 1500 m. In view of the problems of poor stability of deep soft coal shaft lining and difficult fracturing transformation, a series of technical breakthroughs have been carried out on deep coalbed methane in Qinshui Basin. Research shows:The KCL polymer+borehole strengthening agent drilling fluid system is used in the drilling process, can effectively control the enlargement rate of the coal seam diameter. Use 16~18 m3
/min ultra- large displacement, high liquid volume and high sand volume smooth casing fracturing technology, and use resistance reducing agent to reduce construction friction. The proportion of fine sand, medium sand and coarse sand is 15%, 70% and 15%. The sand carrying liquid sand ratio has been gradually increased since 3%, increase by 1% each time, which can realize the full transformation of deep soft coal. The maximum dynamic half length of the fracture reaches 322.51 m, greatly increasing the control area of a single well, and the effect of gas drainage and production is good.