Abstract Surfactant flooding is one of the most widely adopted enhanced oil recovery strategies whereby microemulsion is formed in situ during immiscible displacement. It is expected that local equilibrium is achieved during surfactant flooding and that resulting microemulsion phase properties directly influence the flow physics and thus, oil recovery. We consider phase behaviour of a surfactant–oil–water system that can form either Winsor type II−, III or II+ microemulsion. Water, polymer and Winsor type surfactant solutions are injected into oil saturated polydimethylsiloxane microfluidic chips and imaged under continuous flow at various Capillary numbers and Viscosity ratios. Images are analysed for displacement patterns and oil recovery. Flow regimes are explained by considering the equilibrium interfacial tension (IFT) and viscosity of the formed microemulsion phase. Displacement of oil by injected fluids was dominated by capillary fingering at low flow rates. At higher flow rates, type III microemulsion develops viscous fingering while type II− develops stable displacement due to the microemulsion phases being of high and low viscosity, respectively. This report highlights that the difference between stable/unstable displacement during surfactant flooding is influenced by surfactant–oil–water phase behaviour.

中文翻译：

---

表面活性剂驱油期间的流态：相行为的影响

摘要 表面活性剂驱是最广泛采用的提高采收率策略之一，通过在不混相驱替过程中原位形成微乳液。预计在表面活性剂驱油过程中会达到局部平衡，由此产生的微乳液相性质直接影响流动物理，从而影响采收率。我们考虑可以形成 Winsor II-、III 或 II+ 型微乳液的表面活性剂-油-水系统的相行为。将水、聚合物和 Winsor 型表面活性剂溶液注入油饱和聚二甲基硅氧烷微流体芯片中，并在不同毛细管数和粘度比的连续流动下成像。分析图像的位移模式和石油采收率。通过考虑形成的微乳液相的平衡界面张力 (IFT) 和粘度来解释流动状态。在低流速下，注入流体驱油的主要方式是毛细管指法。在较高流速下，由于微乳液相分别具有高粘度和低粘度，III 型微乳液形成粘性指状，而 II 型微乳液形成稳定置换。该报告强调，表面活性剂驱替期间稳定/不稳定驱替之间的差异受表面活性剂-油-水相行为的影响。由于微乳液相分别具有高粘度和低粘度，III 型微乳液形成粘性指状，而 II- 型微乳液形成稳定位移。该报告强调，表面活性剂驱替期间稳定/不稳定驱替之间的差异受表面活性剂-油-水相行为的影响。由于微乳液相分别具有高粘度和低粘度，III 型微乳液形成粘性指状，而 II- 型微乳液形成稳定位移。该报告强调，表面活性剂驱替期间稳定/不稳定驱替之间的差异受表面活性剂-油-水相行为的影响。