适用于双河油田聚驱后油藏的非均相复合驱油体系研究

Heterogeneous combination flooding system for reservoir after polymer flooding in Shuanghe Oil Filed

聚合物驱后油藏储层非均质矛盾加剧,剩余油分布更加分散,常规化学驱进一步提高采收率难度大。针对双河油田北块Ⅱx层系聚驱后中高渗透率砂砾岩油藏特点,设计一种由聚合物、黏弹颗粒驱油剂PPG和高效表面活性剂组成的非均相复合体系,开展了驱剂优选、热稳定性评价及注入方式优化。实验结果表明,得到的P/PPG/S非均相复合体系具有高黏弹、超低界面张力的优异性能,热稳定性能良好,能够有效改善储层非均质性,扩大波及体积,同时提高驱油效率。岩心驱油实验表明,模拟油藏条件下,采用P/PPG与P/PPG/S非均相复合体系组合驱替的方式,聚驱后进一步提高采收率27.8%,从而为双河油田聚合物驱后油藏有效提高采收率提供了一种技术方法。

For the reservoirs after polymer flooding,the heterogeneity is stronger and the remaining oil distribution is more dispersed,conventional chemical flooding in consequence is difficult to further improve oil recovery effectively.Therefore,a heterogeneous combination flooding system consisting of polymer,preformed particle gel(PPG)and highly effective surfactant has been designed according to the features of medium-high permeability sandstone reservoir inⅡx layers of Shuanghe Oil Filed after polymer flooding.Thereafter,the selection of flooding agent,evaluation of thermal stability and Optimization of injection mode have been studied.The experimental results showed that the obtained P/PPG/S system has excellent high viscoelasticity,ultra-low interfacial tension,and thermal stability,which can effectively improve reservoir heterogeneity,expand sweep volume and enhance oil displacement efficiency.Core displacement experiments showed that the oil recovery could further enhance by 27.8%after the combination flooding of P/PPG system and P/PPG/S system under simulated reservoir conditions.Thus it provides a technical method for effectively enhancing oil recovery after polymer flooding in Shuanghe oilfield.