Effect of Imidazolium-Based Ionic Liquids on the Interfacial Tension of the Alkane Water System and Its Influence on the Wettability Alteration of Quartz under Saline Conditions through Contact Angle Measurements

Depleted matured reservoirs contain almost two-thirds trapped oil, which remains unrecovered even after primary and secondary oil recovery methods. Chemical enhanced oil recovery (EOR) methods involve the usage of chemical agents that improve the mobility of the residual oil by mechanisms involving alteration of wettability, viscous fingering reduction within the pay zone, and interfacial tension (IFT) between interfaces of fluids (oil/water) and rock, followed by reduced capillary forces during flooding. Chemical EOR methods need more research for high saline reservoir conditions. In this work, the effect of six imidazolium ionic liquids (ILs) on the IFT of alkane water systems and alteration of wettability of quartz surface was investigated as a function of IL concentration (0-10000 ppm) and temperature (288.15, 298.15, 308.15, and 318.15 K). Initially, the effect of the various ILs on the IFT of the alkane aqueous IL system was studied and compared with the neat alkane water system. Subsequently, synergistic behavior of the ILs + NaCI (0-200000 ppm NaCl) on the system aqueous IL + NaCl was performed and compared with the alkane aqueous IL system at zero salinity. Thereafter, the wettability alteration of quartz alkane aqueous IL and quartz crude oil aqueous IL systems, under both zero and high salinity conditions at 298.15 K at atmospheric pressure, was studied using contact angle measurements. The systems with IL showed an increase of contact angle exhibiting an alteration in the wettability from water wet to oil wet, whereas the systems under saline conditions showed a wettability from oil wet to water wet. A synergistic effect of ILs with salt on IFT reduction and wettability alteration has been detected. It is suggested that longer ILs could be a better option for EOR application.