Optimization of Hydraulic Fracture Spacing and Efficient Development Practices for High-Rank CBM Horizontal Wells in Different Regions: A Case Study of Zhengzhuang Block

The “horizontal well with staged multi-cluster fracturing” technology currently serves as the primary development approach for CBM resources in Zhengzhuang Block. However，how to set fracturing parameters under different geological conditions to achieve the best development effect is still unclear. The study conducts a comprehensive analysis of key hydraulic fracturing parameters, including rock mechanics and crustal stress, within the No.3 coal seam of Zhengzhuang Block. On the basis of previous research, a hierarchical analysis method was used to construct a coal rock fracturability evaluation system that includes three factors: brittleness index, horizontal stress difference coefficient, and natural fracture development coefficient, achieving hierarchical zoning of fracturability in the Zhengzhuang block. Using the integrated numerical simulation method of geological engineering, the fracture stage spacing and cluster spacing of horizontal wells in each region were optimized based on the characteristics of fracturability zoning. Ultimately, a segmented cluster selection fracturing parameter optimization method suitable for medium and shallow high-rank CBM horizontal wells was established.Key findings indicate: For Class I zones, recommended stage spacing is 55–65 m with cluster spacing of 20–30 m；Class II zones perform optimally with 50–60 m stage spacing and 15–25 m cluster spacing；Class III zones present high fracture development risks, making them unsuitable for horizontal well development. This achievement has been promoted and applied in 5 newly put into operation hydraulic horizontal wells in the northern ZS58 well area, with a daily gas production increased from the previous 7000m3/d to 15000m3/d, achieving significant results. At the same time, it provides theoretical basis and technical support for the efficient development of medium shallow high-rank CBM horizontal wells.