聚合物驱强化见效机理及注入浓度优化控制

海上油田实施化学驱高效开发新模式,受制于大井距、多层段、强非均质性以及海上平台寿命有限等因素,使得传统聚合物驱方案设计适应性较差且调整余地较小,如何解决这些难题进而科学地对聚合物注入方案进行设计、优化和控制成为新模式在海上油田进一步推广的关键。重点对聚合物驱见效阶段的见效机理及强化见效控制对策进行研究,通过核磁共振实验分析聚合物驱见效阶段不同级别孔隙的动用状况,从微观角度揭示聚合物驱见效机理,并基于数值模拟和代理模型对见效阶段注入浓度优化控制方法展开研究。结果表明:(1)注入聚合物溶液体系的适应性在见效阶段体现为体系的微观流度比改善能力对不同级别孔隙不同油水分布状况的匹配性;(2)对于见效阶段而言,优化目标实际上是加强动用均衡性,强化见效,使在后期更加难以动用的小孔隙在见效阶段得到有效动用;(3)在代理模型思想指导下,建立了注入浓度与强化见效主控因素之间的响应面决策模型,可以快速、有效指导聚合物驱全过程注入参数方案设计。

Effective Mechanism and Optimal Control of Injection Concentration in Polymer Flooding

Affected by large well spacing, multilayer section, strong heterogeneity, and limited life of offshore platforms, conventional design methods of polymer flooding show poor adaptability and less room for adjustment in offshore oilfields. How to solve these problems scientifically becomes the key to further promote chemical flooding in offshore oilfields. The paper focuses on the effective mechnaism of polymer flooding and the optimal countermeasures. Through analysis of NMR experiment results on producing status of different pores, the effective mechanism of polymer flooding was summarized. Based on the numerical simulation and surrogate model, the optimal control of injection concentration was studied. The results indicated that the effective adaptability depended on the matching ability of the injected polymer solution on the formation fluid. For the effective stage, the optimization goal was actually to strengthen the effetive balance, thus to produce the oil of small pores which were initially more difficult to produce in later period. Under the guidance of surrogate model, the calculation model was finally established between the injection concentration and main controlling factors. The method could quickly and effectively guide the design of injection parameters of whole polymer flooding process.