Low-Salinity Waterflooding EOR Technique (Investigating the effect of salinity and connate water composition changes on the reservoir wettability)

Extensive experimental work has indicated that low-salinity waterflooding is an enhanced oil recovery technique that improves oil recovery by lowering and optimizing the salinity of the injected water. Most of the low-salinity waterflooding studies focused on the injection brine salinity and composition. The question remains, how does the salinity and composition of the reservoir connate water affect the low-salinity waterflooding performance? Therefore, in this work different connate water compositions were used to investigate the role of reservoir connate water on the performance of low-salinity waterflooding.Production enhancement by low-salinity waterflood in carbonate formations is a subject of intense speculation. Several mechanisms are attributed to enhanced oil recovery by low-salinity waterflooding in carbonate formations. Review of experimental data in the literature indicates that the main mechanism involves interaction of Na+, Ci-, Ca2+, Mg2+, SO2- 4 and crude oil carboxylate ions (R-COO-) with the rock in the electrical double layer (EDL) near the surface of carbonate pores, leading to wettability alteration.This paper investigates the effect of salinity and water composition on the low-salinity waterflooding performance by reviewing the performed experimental works in this field.