A critical review on low salinity waterflooding for enhanced oil recovery: Experimental studies, simulations, and field applications

Abstract

Due to the challenges of discovering new energy sources, enhanced oil recovery (EOR) techniques remain a potential area of research interest to produce residual oil in matured reservoirs after the depletion of primary and secondary recovery energy. Low salinity waterflooding (LSWF) is one of the promising research areas of interest in EOR techniques for the micro sweep efficiency of residual oil saturation. This review paper critically analyzed LSWF potentiality for exploiting residual oil in matured reservoirs. The results revealed that, despite various researchers' findings from developed theories, experimental data, modeling and simulations, single well chemical tracer tests (SWCTT), and pilot tests, there are limited studies that analyzed and addressed in detail the field application of LSWF due to unclear mechanisms, inconsistency research findings, and failure on SWCTT and pilot tests. Further, this paper describes LSWF's activities that led to the success of LSWF field application in the Pervomaiskoye oil field in Russia and Clair ridge in the United Kingdom (UK) towards entire field operations after the first oil production in 2018. Furthermore, the study showed that the formation damage has positively impacted oil recovery by mobilizing residual oil in unswept areas. The identified research gaps, such as dominant mechanism on LSWF, modeling and simulations of fluid-fluid interactions effects, osmotic effects contributions on LSWF, etc., and findings of this paper shall help different researchers and shareholders to conduct more research to meet global energy for the future demands. The challenges which need to be considered towards successfully full field LSWF operations includes reservoir heterogeneity problems, scaling problem, clay swelling, quality of injected water, cost of the projects, salt dispersion and brine mixing, health and safety issues, environmental issues, etc. On the contrary, from laboratory studies, few simulation studies, and few pilot field applications, hybrid LSWF has shown a great potential to increase oil recovery over LSWF. However, due to additional cost of chemicals could make a hybrid LSWF challenging economically in the full field application.