Iranian Journal of Oil and Gas Science and Technology

Abstract The increasing demand for hydrocarbons has prompted new recovery strategies by applying nanoparticle–surfactant flooding in chemical-enhanced oil recovery (CEOR). Some mechanisms that improve oil mobility are rock wettability alteration and reduced interfacial tension between the oil and water. In this work, silica (SiO₂) nanoparticles (NPs) were synthesized and characterized, and their effect on wettability alteration and interfacial tension (IFT) between the oil and SiO₂ nanoparticles (NPs) dispersed in sodium dodecyl sulfate (SDS) solutions was determined. Experiments on oil displacement by flooding with brine and NPs dispersed in an SDS solution were investigated in a micro glass model. X-ray diffraction (XRD) pattern and scanning electron microscopy (SEM) confirmed the mineral structure and platy polycrystalline morphologies that gave an estimated particle size of 88 nm using Scherrer’s formula. Fourier transform infrared spectroscopy (FTIR) showed characteristic symmetric and asymmetric stretching vibrations. The measured wettability alteration and IFT showed changes in wettability from water-wet toward a more water-wet condition and decreased IFT, respectively, as the SDS concentration increased. The optimum oil recovery of 67.45% was obtained at 2.08 mM SDS when SDS concentrations were varied (2.08, 6.25, 8.33, 10.42, and 14.58 mM) at a constant concentration of SiO₂ NPs (0.1 wt %). Having obtained the optimum oil volume from OOIP at 2.08 mM SDS, SiO₂ NPs concentration varied (0.05, 0.1, 0.15, 0.2, and 0.25 wt %) at a constant SDS concentration (2.08 mM). This optimized approach gave an excellent total oil recovery of 78.36% at 0.2 wt % SiO₂ NPs. Therefore, 0.2 wt % SiO2 NPs with 2.08 mM SDS should be applied in oil recovery.