Study on the Production Characteristics of Deep Coalbed Methane Fractured Horizontal Wells

Deep CBM is primarily stored in coal reservoirs deeper than 2000 m, characterized by high in-situ stress and low permeability. Currently, large-scale fractured horizontal wells have become an effective development method, with initial single-well production rates reaching 2–10 × 104 m3/d, demonstrating favorable development outcomes. However, due to the high overall investment required for large-scale fractured horizontal wells and the complexity of stage-cluster parameter design, evaluating the reserve production characteristics under different fracturing scales and parameters has become a key factor in optimizing deep CBM fractured horizontal wells.To assess the production characteristics and development patterns of deep CBM fractured horizontal wells, a geology-engineering integrated model was established. This model evaluates the production efficiency of free gas and adsorbed gas under different reservoir conditions and analyzes key indicators such as hydraulic fracture propagation, single-well productivity, and estimated ultimate recovery (EUR) under varying fracturing scales, stage counts, and cluster counts. The study also identifies critical engineering factors influencing deep CBM production. The research indicates that due to stress conditions, permeability, and the multi-phase gas storage mechanism, the production performance of deep CBM fractured horizontal wells is significantly influenced by hydraulic fracture geometry. The effective drainage radius of free gas is approximately twice that of adsorbed gas. Under well spacing of 300–400 m, reducing cluster counts to promote dominant, elongated fractures enhances production efficiency and increases EUR. Conversely, for well spacing of 200–300 m, adopting fewer stages with more clusters helps mitigate inter-well interference and improves development effectiveness.