Abstract: Usually there are multiple injection-production blocks in large depleted gas reservoirs, and too high formation pressure difference between blocks can destabilize the reservoir. In order to achieve balanced variation of formation pressure during the injection and production, an optimization model was established with the minimal variance value of formation pressure between periodic blocks as the objective function. The model combined the mathematical optimization technology with the safety and stability of the gas storage, and takes the number of production wells in each block and the injection and production volume of single well as the decision variables, and takes the total amount of gas injection and production of the gas storage, the maximum injection and production volume of single well, and the maximum formation pressure of the block as constraints. The optimization model was applied to Wen23 gas storage based on a large depleted gas reservoir, and the optimized injection-production solution for the gas storage was successfully solved under the condition of an annual gas working volume of 30×10⁸ m³/a. The results of the study showed that the optimized injection-production scheme can not only reduce the formation pressure difference between blocks and achieve a balanced change in the overall formation pressure in the gas storage, but also effectively avoid the occurrence of extremely high pressure blocks and further guarantee the safe and stable operation of the gas storage, on the premise of meeting the requirements of gas injection-production rate in the gas storage. There is much for reference of the study results for the design of the injection- production solution of the gas storage.

Key words: gas storage based on depleted gas reservoir, injection-production optimization, numerical simulation, formation pressure