Research on improving injection and production gas capacity based on integrated reservoir-well coupling model for gas storage

Underground gas storage facilities, used for natural gas storage and peak shaving, are increasingly important for natural gas production and balancing supply and demand. During operation, the working gas recovery volume is a key indicator of peak shaving capacity and operational efficiency. This study performed secondary development on the reservoir geological model constructed by commercial software through the implementation of MATLAB programs. Taking the bottom hole flowing pressure as the coupling point, the numerical simulation model of the gas storage reservoir, the single well simulation model of the wellbore, and the coupling model solving process were integrated into a complete integrated coupling model of the wellbore-gas reservoir. This model integrates geological structure, lithological characteristics, fluid properties, and numerical simulation techniques. It comprehensively considers the flow characteristics of gas reservoir fluids and two-phase flow in wellbores. It can incorporate the injection and production capabilities of individual gas wells in the gas storage reservoir, as well as various stimulation measures, enabling systematic simulation and analysis of the impact of increasing the number of low-yield wells and enhancing injection volume. Separate predictions and comparisons were conducted for eight low-productivity wells, with actual and predicted production data at each production point being compared. The results indicate that the prediction accuracy is 91.3 %. For scenarios where injection and production capabilities fail to meet standards due to various factors, three feasible countermeasures-acidizing and plug removal, deep penetration perforation, and small-scale fracturing-are proposed following a comprehensive analysis. Building on the previous analysis of the primary controlling factors for low production, in-depth investigations into acid fracturing, small-scale fracturing, and deep penetration perforation were conducted for the three gas wells in the gas storage reservoir. For Well A, formation acidizing was performed, resulting in a 16.2 % increase in injection capacity and a 39.2 % increase in production capacity. For Well B, a small-scale fracturing treatment was implemented, resulting in a 30.8 % increase in injection capacity and a 76.7 % increase in production capacity. For Well C, water jet deep penetration perforation technology was employed to remove near-well formation contamination, resulting in a 13.4 % increase in injection capacity and a 25.4 % increase in production capacity. This model comprehensively considers geological structure, lithological features, and fluid properties, conducting a thorough assessment through numerical simulation technology. It thereby provides scientific support for engineering decision-making in gas storage and guides production scheduling and injection-production scheme.