Low salinity water injectionat different reservoir rocks: Similarities and differences

A literature review of laboratory and field scale studies on low salinity water (LSW) injection showed that the salinity and composition of injected water can have a significant impact on oil recovery. Historically, extensive research has been completed to understand the mechanisms and factors affecting LSW injection. However, although numerous mechanisms have been proposed to describe the interactions in the target process, none have been widely accepted. In this study, waterflooding tests were used to investigate the advantages, disadvantages, and effect of LSW injection. In laboratory tests, two different brines and crude oil of one of Iran's southern reservoirs were used to assess the oil recovery factor and the role of wettability alteration. The study aim was to investigate the relationship between wettability alterations and enhancements to the oil recovery factor during LSW injection in sandstone and carbonate samples. The results show that LSW injection results in a change in the wettability from oil-wet to mixed-wet conditions. This alteration causes a slight improvement in oil recovery from sandstone samples. Furthermore, when reducing the salinity of the injection fluid into carbonate samples, which lowers the concentration of active ions, no further increase in the water-wet state is observed.