“…It is reported that the degree of oil recovery improvement relies on multicomponent ion exchange, clay contents, formation water composition, oil composition and initial water saturation. A few mechanisms have been proposed to explain the positive effect, including: migration of fines (Tang and Morrow, 1999), interfacial tension reduction (McGuire and Chatham, 2005), multicomponent ionic exchange (Lager et al, 2008), PH driven wettability change (Lager et al, 2008;McGuire and Chatham, 2005), double-layer expansion (Ligthelm et al, 2009), desorption of organic material from clay surface (Austad et al, 2010), wettability alternation (Yousef et al, 2012), mineral dissolution (Aksulu et al, 2012), and microscopically diverted flow (Skauge 2008;Spildo et al 2012). These mechanisms lead to modification of rock wettability from oil-wet or intermediate/water wet; therefore, residual oil saturation is reduced, and ultimate oil recovery is improved.…”