Research on key factors of CBM well productivity in deep strata inblock of south Yanchuan

Unclear understanding on the factors influencing the productivity of deep buried CBM wells has restricted the commercial exploration. Firstly, the paper summarized the style and capacity of CBM production, then analyzed the factors influencing productivity from resource, difficulty of desorption and fluid condition. The results show that permeability and gas content are the major influence factors of productivity. The constant gas rate of flow is above 1 000 m³/d when the permeability is more than 0.3×10^-3 μm² and the gas content is more than 15 m³/t. Gas content is mainly influenced by depth and hydrodynamic condition, while permeability is mainly controlled by crustal stress, deformation and crack condition. Based on permeability and gas content, the block was divided into four parts and the productivity of each part was evaluated. The correlation between the productivity and fracturing operation parameters are poor, which revealed that the effect of different fracturing operation was basically the same in current technological level.