Prediction model for fracturing incremental recovery of damaged well in low-permeability reservoir and sensitivity analysis

The equivalent start-up pressure gradient within the fracturing radius decreases after reservoir fracturing.A low velocity flow equation including start-up pressure gradient was introduced in the productivity prediction model of fractured wells in low-permeability reservoir.And a prediction model for fracturing incremental recovery of damaged well was developed in radical and steady flow conditions.The influencing factors for productivity of damaged well after fracturing were analyzed.The results show that the variation of start-up pressure gradient has a great effect on productivity of damaged well after fracturing.The contributions of semi-length and width of fractures to incremental recovery are different.Furthermore,the contributions of fracture parameters and improving level of factor skin to incremental recovery have optimization values.