Coupling of fracture model with reservoir simulation to simulate shale gas production with complex fractures and nanopores

Abstract

A novel integrated approach that couples hydraulic fracturing and production simulation was proposed for Marcellus shale gas reservoir. A discrete element method based hydraulic fracturing simulator was utilized for multi-stage hydraulic fracturing simulation. Moving tip clustering (MTC) and linear regression clustering (LRC) algorithms were proposed to characterize the complex fracture geometry. Embedded discrete fracture model method was used to transfer the complex geometry of multiple fractures into a third-party reservoir simulator for history matching of shale gas production and production forecasting. It was observed that the LRC algorithm can generate smooth fracture geometries and detect overall fracture paths reasonably. The MTC algorithm, however, can capture more branches of microcracks and recover zig-zag fracture paths with larger apparent fracture lengths. The zig-zag fractures contribute to larger stimulated reservoir volume and result in an extra shale gas production of 5.2% compared to the smooth fractures. The gas slippage effect increases apparent matrix permeability to 4.6 times of intrinsic permeability. Reduction of fracture conductivity and matrix permeability due to decreasing bottomhole pressure leads to 9.25% and 9.28% decrease of gas production respectively in 30 years and should be taken into account for long-term production prediction.