A Novel Analytical Model for Estimating Shale Gas Production Considering Stress Sensitivity and Pressure Drawdown Management

Summary Hydraulic fracturing could enhance shale gas recovery but induce stress sensitivity. Pressure drawdown management is needed to reduce the impact of stress sensitivity during shale gas production. However, there is still a lack of an analytical model for predicting shale gas production under pressure drawdown management considering stress sensitivity. Based on multicoupling mechanisms, we established a novel analytical model to predict the production under pressure drawdown management by coupling the material balance equation and productivity equation. First, model validation was carried out based on real parameters of the W shale gas reservoir. Then, sensitivity analyses were conducted to reveal the impact of porosity, permeability, stress sensitivity, and fracture properties on shale gas production. Finally, the coupled model was applied to two wells of the W shale gas reservoir for history matching and production forecasting. The error of the novel model was less than 5%, compared with numerical simulation. When the stress sensitivity parameter a increased from 3 to 5, the cumulative gas production with pressure drawdown management rose approximately 64% and the incremental rate of that decreased from 9.2% to 6.3%. Under pressure drawdown management, the cumulative gas production of the well with inferior petrophysical properties exhibited a marginal superiority over the well with superior reservoir characteristics. The results show that pressure drawdown management can alleviate stress sensitivity. The novel model can be applied to predict shale gas production with pressure drawdown management. This work provides theoretical support for optimization of the efficient development strategies to mitigate gas production decline caused by stress sensitivity.