Factors and Mechanisms Governing Wettability Alteration by Chemically Tuned Waterflooding: A Review

Abstract

Enhanced oil recovery (EOR) techniques are aimed at improving the recovery efficiency of mature oil fields in secondary and tertiary recovery modes. In particular, chemically tuned waterflooding (CTWF) has been a rising EOR technique toward improving oil recovery from rocks that are difficult to produce due to their initial wetting state, e.g., oil-wet and intermediate-wet. With an increasing oil-wetting affinity of a reservoir rock, extraction of oil becomes more challenging. As such, wettability alteration has been identified as the primary mechanism for oil recovery from oil-wet and intermediate-wet rock types. Recently, researchers have attempted to categorize the factors and mechanisms governing wettability alteration by CTWF. Multiple studies have identified the importance of brine salinity and ion composition on promoting wettability alteration to a more favorable water-wet state. Reservoir temperature, the surface charge of the rock, and the surface active components of crude oil are also reported to influence wettability alteration and therefore oil recovery from waterflooding. In this paper, we present an extensive literature review on the subject of wettability alteration, with an emphasis on experimental work conducted on carbonate and sandstone rocks, as they constitute the majority of the oil reserves in the world. The purpose of this review paper is to synthesize the current state of knowledge regarding the factors and mechanisms that govern wettability alteration by CTWF and, through this exercise, set the platform to pose new research questions.

Investigating the effect of transient flow behavior from HSW to LSW on oil recovery in low-salinity water flooding simulation

“…Different physicochemical mechanisms have been proposed to validate wettability alteration as one of the primary causes of oil recovery enhancement by LSW flooding in sandstone and carbonate rocks. These mechanisms are classified as salting-in, multiple ion exchange (MIE), fines migration, EDL expansion, mineral dissolution, and pH modification (Purswani et al 2017).…”

“…To illustrate the phenomenon of rock dissolution in carbonate reservoirs, zeta potential measurements were performed by Yousef et al (2011), as it has been widely applied for determining the surface charge of a rock in a particular brine environment (Esmaeili et al 2016;Rahbar et al 2017;Vinogradov et al 2010). Their results revealed a reduction of the carbonate surface zeta potential with a decrease in brine salinity, which suggested that Ca 2+ ions migrated from the rock surface toward the low-salinity brine to re-establish chemical equilibrium between the bine and rock (Purswani et al 2017). Moreover, the decrease in the positive charge on the carbonate surface in presence of low-salinity water led to the expansion of the electric double layer (EDL) and resulted in a thicker, more stable water film.…”

“…In term of low-salinity water injection, extensive numbers of published data have demonstrated that the interplay of many factors, such as crude oil properties, brine salinity, brine composition, rock mineral composition, and reservoir temperature can affect the oil recovery (Purswani et al 2017). Jadhunandan and Morrow (1995) and Yildiz and Morrow (1996) confirmed that brine composition has an impact on oil recovery in water flooding and it can be changed to optimize water flooding recovery.…”

Compatibility evaluation of modified seawater for EOR in carbonate reservoirs through the introduction of polyphosphate compound

“…Statistical analysis of different proposed mechanisms conducted by Sohal et al (2016) and Afekare and Radonjic (2017) also suggested favorable wettability alteration as the main underlying factor associated with LSWF/MWF successes. It is worth mentioning here that whereas wettability alteration is just the consequence of oil recovery process, the real mechanism could be a combination of different underlying processes whose net outcome is the visible change in wettability (Purswani et al 2017). Lashkarbolooki et al (2016) and Myint and Firoozabadi (2015) conducted extensive reviews of the probable mechanisms of action regarding to the wettability alteration and came to the conclusion that expansion of electric double layer, multicomponent ionic exchange, salt-in effect and dissolution of calcite minerals are possible mechanisms responsible for the wettability alteration of oil-wet carbonate rocks.…”

Brine-Dependent Recovery Processes in Carbonate and Sandstone Petroleum Reservoirs: Review of Laboratory-Field Studies, Interfacial Mechanisms and Modeling Attempts

“…This review addresses the subjects of current interests about gathering information on past and recent developments, and challenges of brine-dependent recovery processes in sandstone and carbonate rocks. There have been several recent summaries that discussed different aspects of this subject [75][76][77][78][79][80][81][82][83]; hence, this review builds upon these summaries to further explore the published data to build theoretical understanding and identify potential opportunities for further investigation. Overall, the outcome of this review will potentially be of immense benefit to the oil industry.…”