极限含水条件下三元复合驱及聚合物驱提高采收率效果分析

On the effectiveness of increasing oil recovery factors with ASP flooding and polymer flooding under the limit water-cut conditions

以大庆油田杏二西油层为例,探讨长期含水100%、地层中的原油以残余油为主条件下化学驱提高原油采收率的问题。在杏二西油层实施了三元复合驱试验,中心井区提高采收率幅度达19.46%,表明对于水驱采出程度非常高、地层中的原油主要是残余油的油层,采用三元复合驱可大规模驱动残余油、大幅度提高驱油效率。三元复合驱提高采收率机理是大幅度提高驱油效率及扩大波及体积,而聚合物驱则仅通过扩大波及体积提高油田采收率,无法提高驱油效率。油田大量实际资料和杏二西油层数值模拟研究表明,对高含水、以残余油为主的油层采用聚合物驱不能提高驱油效率,因而其提高采收率幅度低,对类似杏二西油藏条件的油层不宜采用聚合物驱,而宜采用三元复合驱提高采收率。

Taking the Xing＇erxi ASP flooding test as an example, the paper discusses the issue of increasing oil recovery factor by ASP flooding under the condition of residual oil being dominant in reservoirs with a long-time 100 % watercut. After the ASP flooding, the oil recovery factor in the central well area of the Xing＇erxi reservoir is increased by 19.46% , indicating that the ASP flooding is suitable for reservoirs with a high water flooding oil recovery factor and the remaining oil dominated by residual oil. The mechanism of ASP flooding is to improve oil-displacing efficiency by reducing interfacial tension and expanding its sweeping area. Whereas the polymer flooding can only increase oil recovery factor through enlarging the swept volume but cannot improve the oil displacement efficiency. Oilfield data and the numerical simulation of the Xing＇erxi reservoir show that the polymer flooding can only enhace slightly the oil recovery in this type of reservoirs.