Synergistic Effect of Low Salinity Surfactant Nanofluid on the Interfacial Tension of Oil–Water Systems, Wettability Alteration, and Surfactant Adsorption on the Quartz Surface

Interfacial tension (IFT) and wettability are the two major factors influencing oil recovery. The synergistic effect of low salinity water (LSW) with chemical agents such as surfactants, alkalis, and polymer is an emerging technology for enhanced oil recovery (EOR). Recently, the use of nanoparticles for EOR has become the attractive option. This study examines the impact of low salinity surfactant–silica nanofluid (LSS–SNF) on interfacial tension (IFT) and wettability alteration in an oil–water–quartz system using various types of oils, viz., n-heptane, n-decane, benzene, toluene, model oil A, model oil B, and crude oil. Besides, the adsorption of surfactants on the quartz substrate in the presence of silica nanoparticles is also studied. A quartz substrate is particularly chosen to mimic the sandstone formation. It has been observed that the type of oil has a crucial role in the IFT behavior, and different trends have been observed for model oil A and model oil B in the presence of LSS–SNF. Also, a prominent wettability shift is observed on the quartz substrate for the acidic (model oil A) than the other oil employed. Further, the adsorption studies using an ultraviolet–visible (UV–vis) spectrometer confirm the reduction in surfactant adsorption with an increase in silica nanoparticle concentration. The adsorption of surfactants is also confirmed using scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDXA), and the order of adsorption is identical to the Freundlich adsorption isotherm. The outcomes of this study will help us understand the application of silica nanofluid in EOR operation.