Simulation of flow behaviour through fractured unconventional gas reservoirs considering the formation damage caused by water-based fracturing fluids

Based on the results of the expanded scale simulation, when the effect of water invasion damage on matrix permeability is not considered and only the change of fracture aperture is considered, the ratio of the rate of gas production from fractured formation without any formation damage, fractured formation suffering from the effect of multi-cycle confinement, fractured formation suffering from the combination effect of multi-cycle confinement and water invasion damage, and unfractured formation is around 15.15, 5.14, 2.23, 1 respectively, and the corresponding ratio of total gas production is around 17.62, 4.86, 2.13, 1 respectively, over a 10-year period. If the effects of water invasion damage on matrix permeability and fracture permeability are considered at the same time, the ratio of the rate of gas production rate from fractured formation without any damage on matrix permeability in the damage zone, fractured formation with 30% of initial permeability in the damage zone, fractured formation with 3% of initial permeability in the damage zone, and unfractured formation is around 2.23, 1.69, 0.94, 1 respectively, and the ratio of total gas production is 2.13, 1.54, 0.92, 1 respectively. This indicates that formation damage caused by multi-cycle confinement and fracturing water invasion can greatly impair gas production from unconventional gas reservoirs.