A review of chemical methods for wettability alteration in reservoir rocks

One of the recent important challenges at the forefront of science revolves around the manipulation of surface wettability, i.e., the water affinity to a given surface. The desired wettability of a surface can vary between hydrophilic and hydrophobic, depending on the intended application. Broadly speaking, wettability alteration of an underground reservoir generally entails restoring the initial reservoir wettability, typically assumed to be water-wet. This shift in wettability is important as it enhances the reservoir recovery efficiency in non-water-wet or weakly water-wet formations. In this context, the mechanisms behind wettability alteration, a process that often demands a considerable amount of time, have been the subject of extensive investigation. It constitutes the central component of several newly proposed methods, particularly those involving nanoparticle injection, low salinity (LowSal) water, smart water injection, microbial methods, and chemical solutions injection. Regrettably, despite the substantial body of research focused on the impact of wettability alteration, there is a lack of understanding of a general mechanism and consistent results, making it imperative to consolidate these findings and expand on possible mechanisms regarding wettability alteration in one comprehensive source. To address this gap, the present review concentrates exclusively on recent advances in wettability alteration. This review delves into recently proposed wettability alteration mechanisms and the molecular arrangements on rock surfaces, thereby clarifying the possible options for wettability alteration.