Numerical Study on the Evolution of Reservoir Pressure and CBM Concentration Considering Hydraulic Fractures

Based on the theories of mass conservation and coalbed methane (CBM) adsorption/desorption, this paper first establishes a novel reservoir pressure model for CBM production, following which, concentration production models are also proposed. Then, these programmed solved by means finite element method. Taking Hunchun field in Jilin province, China, as an example, pressure, gas concentration, characteristics under different hydraulic fracture forms simulated investigated. In conclusion, decreases very rapidly small region near tip, which we called “reservoir singularity”. The existence greatly reduces process exploitation. permeability sensitivity coefficient Rpk, is defined to quantitatively describe influence coal seam evolution pressure. Rpk logarithmically distance from extraction well increases. recovery rate presence multiple fractures We believe results could contribute design fracturing wells evaluation reservoir.