This study presented a pore-scale investigation on the dynamic displacement of oil subjected to ex-situ and in-situ surfactant flooding using X-ray microtomography. The ex-situ surfactant solution was pre-prepared, whereas the in-situ surfactant was generated directly with the chemical reaction inside porous media. The results showed that oil removal from the pore spaces relied on the combination of piston-like, pore-body filling and a weak emulsification mechanism in the ex-situ system, whereas the in-situ system was dominated by a strong emulsification process. The threshold capillary pressure was decreased significantly owing to interfacial tension reduction and wettability alteration, which enhanced the oil cluster mobilization. Therefore, the in-situ system produced the highest oil recovery efficiency of 86.9% compared with ex-situ system and water flooding. The emulsifying ability was evaluated through oil cluster size distributions and their dynamic evolution. The networks or branches disappeared and emulsified into small oil ganglia and singlets, thereby leading to a significant decrease in the average equivalent diameter. Finally, strong emulsification in the in-situ system was attributed to quick and precise surfactant aggregation at the oil–water interface that induced blebbing, whereas the ex-situ case was dominated by slow surfactant transport relying on advection and diffusion in the flow mainstream.

这项研究使用X射线显微断层摄影技术对油在异位和原位表面活性剂驱油后的动态驱替进行了孔隙尺度研究。预先制备了表面活性剂溶液，而表面活性剂是通过多孔介质内部的化学反应直接生成的。结果表明，在异位系统中，从孔隙中除油依赖于活塞状，孔体填充和弱乳化机制的结合，而原位系统则以强乳化过程为主。由于界面张力的降低和润湿性的改变，毛细管的阈值压力显着降低，这增强了油团的动员。因此，原位系统产生的最高采油效率为86。与异地系统和注水相比，减少了9％。通过油团尺寸分布及其动态演变来评价其乳化能力。网络或分支消失并乳化成小的油神经节和单线态，从而导致平均当量直径显着减小。最后，在原位系统中强烈的乳化作用归因于表面活性剂在油-水界面处快速而精确的聚集，从而引起起泡，而在非原位情况下，表面活性剂的缓慢迁移主要依靠对流和在主流中的扩散。从而导致平均等效直径的显着减小。最后，在原位系统中强烈的乳化作用归因于表面活性剂在油-水界面处快速而精确的聚集，从而引起起泡，而在非原位情况下，表面活性剂的缓慢迁移主要依靠对流和在主流中的扩散。从而导致平均等效直径的显着减小。最后，在原位系统中强烈的乳化作用归因于表面活性剂在油水界面的快速和精确聚集，从而引起起泡，而在原位情况下，表面活性剂的缓慢迁移主要依靠对流和在主流中的扩散。