Effects of 'soft-hard' compaction and multiscale flow on the shale gas production from a multistage hydraulic fractured horizontal well

In this study, the shale gas production from a multistage hydraulic fractured shale gas reservoir was analyzed. Firstly, the reservoir was divided into single-porosity medium zone, dual-porosity medium zone, and hydraulic fracture zone. Then, a mathematical model was established for the multiscale gas diffusion and adsorption/desorption mechanisms in matrix, the gas flow in fractures and the interaction between gas flow and shale deformation. Thirdly, this mathematical model was numerically solved within the platform of Comsol Multiphysics and verified by the history matching of the gas production data from Barnett and Marcellus shale reservoirs. Finally, sensitivity study was conducted to identify key parameters to the efficiency of gas recovery enhancement. It is found that hydraulic fracture aperture and initial permeability of fractures are positively correlated with gas production rate. The 'soft - hard' compaction of fractures can significantly modify gas production rate but the modification varies with gas production stage. The deformation and flow properties of hydraulic fractures have significant impacts on gas production rate, particularly in the early stage.