Wettability alteration and interfacial tension (IFT) reduction in enhanced oil recovery (EOR) process by ionic liquid flooding

Nearly half of the world's known oil reserves are in the carbonate rocks. Water flooding recovery from these reservoirs is low and therefore, these reservoirs are good candidates for enhanced oil recovery (EOR) processes. Surfactant flooding which is subset of chemical enhanced oil recovery (CEOR) can increase the recovery from these reservoirs by reduction of interfacial tension (IFT) and alteration of wettability. The purpose of this study was to investigate wettability alteration and IFT reduction by ionic liquids (ILs) as a new family of surfactants. The work started by screening four ILs, namely [C12mim][Cl], [C18mim][Cl], [C8Py][Cl] and [C18Py][Cl], based on pendant drop and contact angle tests for measurement of interfacial tension and wettability. Then, coreflooding test was then performed to study the effect of the selected ILs on ultimate oil recovery in core plug from carbonate oil reservoir. Based on the screening process, [C18mim][Cl] was found to be the optimum IL. Coreflooding with the selected IL revealed 13% increase in oil recovery compared to flooding with brine.