Wettability alteration has been recognized as the dominant mechanism of ion-tuned waterflooding, where the ionic composition of injecting brine is modified to improve oil recovery. Yet mechanisms of ion-tuned wettability have not been fully understood, and there are ongoing debates over the effectiveness and relative contribution of each mechanism. In this paper, ion-tuned wettability in variable oil-brine-rock (OBR) systems over a wide range of ionic compositions is theoretically investigated, with focuses on two electrokinetic mechanisms, double layer expansion (DLE) and multicomponent ion exchange (MIE). Results indicate that the qualitative features of ion-tuned wettability in terms of DLE and MIE in various OBR systems with different surface properties can be divided into two typical types, depending on the electrical double layer (EDL) interaction being repulsive or attractive. With attractive EDL force, both DLE and MIE do not contribute to the water-wetness. While with repulsive EDL force, DLE only takes effect at relatively high concentration and MIE has a significantly larger impact at a low percentage of divalent cation. In addition, DLE and MIE can have a synergistic effect, where one mechanism alone has a negligible effect on wettability but two mechanisms combined have a big impact.

润湿性改变已被认为是离子调谐注水的主要机理，其中注入盐水的离子组成经过改性以提高采油率。然而，离子调节润湿性的机理尚未完全理解，并且关于每种机理的有效性和相对贡献的争论仍在不断。在本文中，从理论上研究了可变油盐岩（OBR）系统中各种离子组成下离子调谐的润湿性，重点研究了两种电动机理，即双层膨胀（DLE）和多组分离子交换（MIE）。 。结果表明，在具有不同表面特性的各种OBR系统中，根据DLE和MIE进行离子调节的润湿性的定性特征可以分为两种典型类型：取决于双电层（EDL）的相互作用是排斥的还是有吸引力的。在有吸引力的EDL力的作用下，DLE和MIE都不会增加水的润湿性。在具有排斥性的EDL力的情况下，DLE仅在相对较高的浓度下才起作用，而MIE在低百分比的二价阳离子下具有明显更大的影响。此外，DLE和MIE可以起到协同作用，其中仅一种机理对润湿性的影响可忽略不计，而两种机理的结合则具有很大的影响。