二元复合驱注采参数优化方法研究

二元复合驱已在胜利、大庆等油田工业化应用,但矿场上普遍采用的笼统均匀注剂方式没有考虑地层条件差异,容易造成高价化学剂利用效率不高,无法完全发挥其降水增油作用。以经济净现值为目标函数,考虑矿场注入能力及地层条件限制建立约束条件,给出二元复合驱注采优化模型,并利用最优扰动近似梯度法进行求解。结果表明:在聚合物和表面活性剂总注入成本恒定的条件下,通过优化调配各注入井的聚合物质量浓度、表面活性剂质量分数和段塞尺寸,油藏累积采出程度相比均匀注剂方案提高1.23％,经济净现值提高977.8万元。优化结果说明提出的二元复合驱注采参数优化方法能够辅助设计高效合理的二元复合驱开发方案,对提高二元复合驱开发项目的经济、技术效益具有一定的指导意义。
Polymer/surfactant binary flooding has been widely applied in Shengli, Daqing and other oilfields in China. However, the general and uniform injection methods used in the oilfield have not fully taken into account the difference of the formation and geological conditions, which can readily cause a low flooding efficiency with high chemical cost. In this study, taking the net present value of a project as the objective function, and considering the constraint conditions of the field injection capacity and the restriction of the formation conditions, an optimization model of the injection and production for the binary flooding was established, which was solved by an optimal perturbation approximation gradient method. The results of a case study show that, under the conditions of a constant total injection cost of polymer and surfactant, by optimizing the concentration of polymer, the concentration of surfactant and slug size of each injection well, the accumulated oil production can be increased by 1.23％, and the net present value of the project can be increased by over 9 million yuan. The optimization results show that the optimization method of the injection and production parameters of polymer/surfactant binary flooding can be effectively used in the project design to improve the economic and technical benefits of the project