Synergistic effects of alkalines, salts, and silica nanoparticles on in-situ surfactant generation from different crude oils in relation to enhanced oil recovery

The objective of this study was to evaluate the potential of three selected Iranian crude oils for in-situ surfactant generation in relation to alkaline-assisted enhanced oil recovery. The individual and synergistic effects of different alkaline agents, monovalent and divalent salts, and silica nanoparticles (SiO₂) were investigated using interfacial tension and contact angle measurements. In addition, zeta potential (ZP), elemental analysis (EDXA), X-ray Fluorescence (XRF), Hydrogen Nuclear Magnetic Resonance (H-NMR), and Fourier transform infrared Spectroscopy (FTIR) were conducted to assess these effects comprehensively. The results showed that the simultaneous use of two alkalines had a positive effect on interfacial phenomena. The surfactants produced using the heaviest oil in this study (Crude Oil C) have shown the best effects. The interfacial tension was decreased from 35.5 mN/m to 1 mN/m. Furthermore, incorporating silica nanoparticles into the optimal formulation yielded the greatest impact, reducing the interfacial tension to 0.69 mN/m. Additionally, the combination of silica nanoparticles (SiO₂), sodium sulfate, and alkaline agents altered the wettability of mineral samples from oil-wet to water-wet conditions. After 14 days aging times, the contact angle for glass changed from 114 ° to 47 °, and for calcite from 108° to 49°. The results of this study should be considered as an initial screening of oil types for the combined use of alkaline and nanoparticle in enhanced oil recovery operations.