Recent advances on the application of low salinity waterflooding and chemical enhanced oil recovery

Enhanced oil recovery (EOR) is used to retrieve capillary trapped and bypassed oil in the reservoir. Accordingly, laboratory and field applications of chemical EOR (CEOR) methods have been evaluated with varying degrees of efficiency. Nonetheless, the chemicals tend to precipitate in harsh reservoir conditions, thereby inhibiting the efficiency of the EOR process. Low salinity waterflooding (LSWF) is another EOR technique that has been gaining prodigious attention for recovering additional oil from the reservoir due to its sterling properties. However, LSWF has a low oil recovery efficiency especially in heavy oil reservoirs. Recently, the synergic combination of LSWF with chemical EOR has been exploited, explored, and evaluated. Herein, the type, mechanism, and efficiency of the newly devised hybrid EOR method have been reviewed. Moreover, its application is evaluated for sandstones and carbonates. Experimental and modeling results revealed that the combination of LSWF and chemical EOR yields a higher efficiency compared to the individual EOR method. The interplay of underlying mechanisms during the hybrid process resulting in higher oil recovery efficiency was elucidated. Finally, gaps in research and recommendation for future studies were highlighted.