Pore-scale study of in-situ surfactant flooding with strong oil emulsification in sandstone based on X-ray microtomography
Pore-scale study of in-situ surfactant flooding with strong oil emulsification in sandstone based on X-ray microtomography
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DOI：
10.1016/j.jiec.2021.03.046
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发表时间：
2021-04
影响因子：
6.1
通讯作者：
Yun She;Chunwei Zhang;M. Mahardika;Anindityo Patmonoaji;Yingxue Hu;Shintaro Matsushita;T. Suekane-T.-Suekan
中科院分区：
文献类型：
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作者：
Yun She;Chunwei Zhang;M. Mahardika;Anindityo Patmonoaji;Yingxue Hu;Shintaro Matsushita;T. Suekane-T.-Suekan
本文采用x射线显微层析成像技术，在孔隙尺度上研究了非原位和原位表面活性剂驱油的动态位移。原位表面活性剂溶液是预先制备的，而原位表面活性剂是在多孔介质内通过化学反应直接生成的。结果表明：非原位体系以强乳化作用为主，而非原位体系以活塞式、孔体填充和弱乳化作用相结合的方式进行脱油；界面张力的降低和润湿性的改变显著降低了阈值毛细压力，增强了油簇的动员。因此，与非原位体系和水驱相比，原位体系的采收率最高，达到86.9%。通过油簇大小分布及其动态演化来评价其乳化能力。网络或分支消失并乳化成小的油神经节和单链，从而导致平均当量直径显著减小。原位体系的强乳化作用主要是由于表面活性剂在油水界面上的快速、精确聚集引起的气泡，而非原位体系则主要是表面活性剂在流动主流中依靠平流和扩散的缓慢输送。
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.