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Abstract A comprehensive gas-flow model for shale gas reservoir is significantly important for the dynamic analysis of gas production and reservoir simulations. This paper proposed a hydro-mechanical model for shale gas reservoir that was considered as dual permeability media of matrix pore and fracture. The Knudsen flow in porous matrix and Darcy flow in fracture network were assumed. The model involves multiple flow regimes，gas adsorption/desorption，and stress-sensitive effect. Finite element method was used to discretize the governing equations by fully implicit discretization schemes，and thus corresponding code was made. A numerical example was presented using the proposed model and field shale parameters. Results show that the pressure-declined rate of shale gas reservoir is less than that of conventionally fractured reservoirs. Fracture permeability is a primary factor of reservoir pressure depletion. It is necessary to make the flow conductivity of fractures match with the gas production from shale matrix. The initial pressure has a major effect on the fracture pressure depletion，which indicates that the less initial pressure is，the less fracture pressure depletion is. The presented model and code are helpful for understanding shale gas production and developing the shale-gas reservoir simulator.
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Received: 12 December 2012
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2013, Vol. 32 
