A Multi-Objective Constraint Framework for Optimizing Wellhead Pressurization Schemes in Changning Shale Gas Wells

More than 70 shale gas wells have been pressurized in the Changning Block; however, field applications have shown inconsistent stimulation performance and a lack of quantitative guidance for designing rational pressurization schemes. In this study, pressurized shale gas wells in the Changning 201 well area were investigated to establish a multi-objective constraint framework for optimizing pressurization strategies. The framework integrates key techno-economic constraints, including sand production risk, wellbore liquid loading, inflow performance, and incremental gas production. Using fracturing treatment, wellbore configuration, and production performance data from 46 pressurized wells, sand production prediction, liquid-loading diagnosis, and inflow performance analyses were conducted. A quick-look chart was then developed to rapidly determine the optimal pressurization magnitude based on the pre-stimulation gas rate and wellhead pressure of a target well. Field application in nine wells resulted in a total daily incremental gas production of 2.5 × 104 m3 d−1 and an annual cumulative incremental production of 348 × 104 m3, with production efficiency increasing by 25.9 percentage points. Among ten wells subjected to individual wellhead pressurization, seven achieved the expected performance, whereas the remaining three underperformed because of well-specific constraints. These results demonstrate that the proposed framework can provide quantitative support for rational pressurization design and production restoration in low-pressure shale gas wells.