| Summary: | A substantial volume of oil is trapped in the reservoir after the primary and secondary recovery processes because of pressure and reservoir heterogeneity. Experimental results have indicated that silica nanoparticle (SNP) flooding is highly efficient in enhanced oil recovery (EOR). The performance is a function of preparation and modification processes. The use of SNP modified by (3–Aminopropyl) triethoxysilane (APTES) is yet to be extensively examined for potential use in EOR. In this study, a modified SNP was examined to determine its influence in EOR applications. Sessile drop technique was utilized to determine the effectiveness of the modified SNP in altering the wettability of the oil-wet sandstone core. Subsequently, the interfacial tension (IFT) between oil and water was also investigated. Furthermore, the oil displacement efficiency of the modified nanofluid was compared with the unmodified. Zeta potential (ζ–potential), Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscope (FESEM), and energy dispersive X–ray (EDX) spectra were used to confirm the modification of the SNP. The results show that APTES adhered to the surface of the modified SNP, and the particles are finely dispersed and stable in aqueous solution. The ζ–potential indicates that the surface charge of the particles increased from −16 mV to +26.4 mV after modification, which indicates long term stability when used in EOR processes. The silica nanofluids (SNFs) altered the wettability of sandstone core from oil–wet at a contact angle of 134.7° to water–wet at a contact angle of 54.3° (modified SNF) and 54.5° (unmodified SNF), at low concentrations. Also, the IFT of the modified SNF was low compared to unmodified SNF and APTES. The oil recovery of water flooding showed 62.9% and it improved to 75% and 69.6% when modified and unmodified SNFs were used, respectively. The pressure drop of the modified SNF was higher compared to the unmodified SNF which confirmed the stability of the modified SNF. Thus, the SNFs were very efficient in mobilizing trapped oil at ambient conditions and is, therefore, recommended for EOR processes.
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