考虑安全稳定运行的大型枯竭气藏储气库注采优化

大型枯竭气藏储气库通常含有多个注采区块,区块间地层压差过高会破坏储层的稳定性。为实现注采过程中地层压力均衡变化,以各周期区块间地层压力方差值最小化为目标函数建立优化模型。该模型将数学优化技术与储气库安全稳定性问题进行了结合,并以各区块开井数和单井注采气量为决策变量,以储气库注采气总量、最大单井注采气量、最大区块地层压力等为约束条件。将所建立的优化模型应用于文23大型枯竭气藏储气库,成功求解了该储气库在年工作气量为30×10⁸m³/a条件下的优化注采方案。研究结果表明,所获得的优化注采方案在满足储气库注采气量要求的前提下,不仅能够降低各区块间地层压差,实现储气库整体地层压力的均衡变化,还能有效避免极端高压区块的出现,进一步保障了储气库的安全稳定运行。该研究成果对储气库注采运行方案的设计具有一定的指导意义。

Optimization of Gas Injection and Production in Gas Storage Based on Large Depleted Gas Reservoir with Consideration of Safe and Stable Operation

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.