Most oil reservoirs are first saturated with water and become oil-wet gradually due to oil migration and accumulation. Previous studies reported that the adsorption of hydrocarbon components onto the rock surface during a considerable time caused wettability alteration from primarily water-wet to oil-wet. However, few studies fundamentally reviewed the effects of the ionic composition of formation water on the process of the rock surface wettability alteration from water-wet to oil-wet using advanced surface analysis tools. In this research, wettability alteration of calcite surface from water-wet to oil-wet and (in the next step) from oil-wet to water-wet was studied using a specific carboxylic acid (stearic acid), normal decane, and three single salt aqueous phases. During this research, the surface was analyzed using contact angle and scanning electronic microscopy. Results showed that using deionized water as an aqueous phase caused maximum surface adsorption of carboxylic components and minimum adsorption occurred in the presence of the MgCl₂ aqueous phase. The carboxylic acid adsorption onto the calcite surface was controlled by interactions of negative ions formed during dissociation of carboxylic acids and positive salt ions present in brine solvents.

大多数油藏首先被水饱和，然后由于石油运移和聚集而逐渐变成油湿。先前的研究报告称，在相当长的时间内，碳氢化合物成分吸附到岩石表面导致润湿性从主要是水湿性变为油湿性。然而，很少有研究使用先进的表面分析工具从根本上回顾地层水的离子组成对岩石表面润湿性从水湿向油湿变化过程的影响。在这项研究中，使用特定的羧酸（硬脂酸）、正癸烷和三种单一的化合物研究了方解石表面从水湿性到油湿性以及（在下一步中）从油湿性到水湿性的润湿性变化。盐水相。在这项研究中，使用接触角和扫描电子显微镜分析表面。结果表明，使用去离子水作为水相导致羧酸组分的最大表面吸附和最小吸附发生在 MgCl 存在下₂水相。羧酸对方解石表面的吸附受羧酸解离过程中形成的负离子与盐水溶剂中存在的正盐离子的相互作用控制。