Water flooding is widely applied for pressure maintenance or increasing the oil recovery of reservoirs. The heterogeneity and wettability of formation rocks strongly affect the oil recovery efficiency in carbonate reservoirs. During seawater injection in carbonate formations, the interactions between potential seawater ions and the carbonate rock at a high temperature can alter the wettability to a more water-wet condition. This paper studies the wettability of one of the Iranian carbonate reservoirs which has been under Persian Gulf seawater injection for more than 10 years. The wettability of the rock is determined by indirect contact angle measurement using Rise in Core technique. Further, the characterization of the rock surface is evaluated by molecular kinetic theory (MKT) modeling. The data obtained from experiments show that rocks are undergoing neutral wetting after the aging process. While the wettability of low permeable samples changes to be slightly water-wet, the wettability of the samples with higher permeability remains unchanged after soaking in seawater. Experimental data and MKT analysis indicate that wettability alteration of these carbonate rocks through prolonged seawater injection might be insignificant.

中文翻译：

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石灰岩中海水注入改变润湿性的实验与模型研究

注水被广泛用于压力维持或增加油藏的采收率。地层岩石的非均质性和润湿性强烈影响碳酸盐岩油藏的采油效率。在向碳酸盐岩层中注入海水的过程中，高温下潜在的海水离子与碳酸盐岩之间的相互作用可以将润湿性改变为更湿润的状态。本文研究了伊朗碳酸盐岩储层之一的湿润性，该储层在波斯湾海水注入下已经使用了十多年。岩石的润湿性是通过使用岩心中上升技术进行间接接触角测量来确定的。此外，通过分子动力学理论（MKT）建模评估岩石表面的特征。从实验获得的数据表明，岩石在老化过程之后正在经历中性润湿。虽然低渗透性样品的润湿性变为微湿，但渗透性较高的样品在海水中浸泡后仍保持不变。实验数据和MKT分析表明，通过长时间注入海水，这些碳酸盐岩的润湿性变化可能不明显。