Simulation of coupled hydro-mechanical-chemical phenomena in hydraulically fractured gas shale during fracturing-fluid flowback

The evolution of pressure, saturation, salinity and aperture profiles of hydraulic fractures, induced fractures and matrix is calculated, revealing the multi-field coupled flowback behavior in fractured gas shale. The sensitivity analysis is also performed to investigate the physiochemical properties of shale on the water load recovery and gas production rate during the fracturing-fluid flowback. The results indicate that the capillarity has the most effect followed by chemical osmosis and induced fracture closure. The sub-irreducible water saturation has the weakest effect. Moreover, the matrix-related physiochemical parameters cause opposite influences on water load recovery and gas production rate. While, the influence of induced fracture-related parameters on both water load recovery and gas production rate is consistent. Results from this study are expected to explain which is the predominant mechanism for fracturing-fluid retention and the inherent relationship between fracturing-fluid flowback and gas production for different initial physiochemical properties of shale.