Abstract This paper presents a dynamic effect of clay types and content on low salinity water-flooding (LSF) based on coreflooding experiments. The EDL (electrical double layer) expansion, MIE (multicomponent ion exchange), local pH increase between clay minerals and brine are investigated to get a better understanding on the complexity of role of clay in LSF. The results of coreflooding experiments using unconsolidated core sample show that the incremental oil recovery of kaolinite is higher than that of illite at the same clay content. Kaolinite and illite have a positive effect on MIE, EDL expansion, and local pH increase. The incremental oil recovery was proportional to the local pH increase in both core samples. Especially, more MIE and EDL expansion occur in kaolinite core samples. Therefore, the wettability is further changed to the water-wet condition in kaolinite sample. The results of correlation coefficient analysis show the kaolinite content has a strong correlation with MIE, EDL expansion, local pH increase, and oil recovery. On the other hand, the correlations between oil recovery and chemical reactions in illite samples are relatively low compared to the kaolinite samples excepting local pH increase. Therefore, the sandstone reservoir containing kaolinite is more suitable for the LSF.

中文翻译：

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低矿化度水驱中粘土矿物与卤水复杂化学反应的实验研究

摘要 本文基于岩心驱油实验，介绍了粘土类型和含量对低矿化度水驱（LSF）的动态影响。研究了 EDL（双电层）膨胀、MIE（多组分离子交换）、粘土矿物和盐水之间的局部 pH 值增加，以更好地了解粘土在 LSF 中的复杂作用。使用松散岩心样品进行岩心驱油实验结果表明，在粘土含量相同的情况下，高岭石的增量采油率高于伊利石。高岭石和伊利石对 MIE、EDL 膨胀和局部 pH 值升高有积极影响。增加的石油采收率与两个岩心样品的局部 pH 值增加成正比。特别是，高岭石岩心样品中出现更多的 MIE 和 EDL 膨胀。所以，在高岭石样品中润湿性进一步变为水润湿状态。相关系数分析结果表明，高岭石含量与 MIE、EDL 膨胀、局部 pH 值升高和采油率有很强的相关性。另一方面，与高岭石样品相比，伊利石样品的采油率与化学反应之间的相关性相对较低，除了局部 pH 值升高。因此，含高岭石的砂岩储层更适合LSF。与高岭石样品相比，伊利石样品中石油采收率与化学反应之间的相关性相对较低，除了局部 pH 值升高。因此，含高岭石的砂岩储层更适合LSF。与高岭石样品相比，伊利石样品中石油采收率与化学反应之间的相关性相对较低，除了局部 pH 值升高。因此，含高岭石的砂岩储层更适合LSF。