Influence of the Pressure Sensitive Effect on the Accuracy of History Matching for Hydraulic Fracturing Wells

Evaluation of the hydraulic fracturing effect of shale gas wells is helpful for the design optimization and the adjustment of hydraulic fracturing schemes. Three history matching examples were performed for shale gas wells in the Weiyuan Shale Gas Field, Sichuan Basin, China. Based on the parameters obtained through history matching, the hydraulic fracturing effect of shale gas wells was evaluated roughly. In order to obtain the history matching results with high accuracy, both the pressure-sensitive effect of the absolute permeability and that of the relative permeability need to be considered fully. If the two pressure-sensitive effects are fully considered, the total relative errors between the fitting and real data of the gas production and of the fracturing fluid recovery were both less than about 5% according to our history matching results. It was also found that the pressure-sensitive effect of the relative permeability had a greater influence on the fitting of the fracturing fluid phase flow than on the fitting of the gas phase flow. If ignoring the pressure-sensitive effect of the relative permeability, the total relative error for the gas production fitting was as low as about 5%, but for the fracturing fluid recovery fitting, the total relative error still remained at about 40%. Theoretical analysis was performed to explain this phenomenon. As a conclusion, it is emphasized that both the pressure-sensitive effect of the absolute permeability and of the relative permeability need to be considered during the history matching, especially for the fitting of the fracturing fluid phase flow.