Influence of Surface Modification on the Interfacial Tension Reduction and Wettability Alteration of Iron Oxide Nanoparticles Under Reservoir Conditions

Iron oxide nanoparticles (IONPs) are at the forefront of advanced materials considered for enhanced oil recovery (EOR), due to their unique physicochemical properties. However, the major drawback is that IONPs quickly agglomerate to diminish their high surface energy, particularly in reservoir brine. Hence, losing their stability and beneficial characteristics which have a negative impact on oil recovery. In this study, these challenges have been circumvented by the functionalization of IONPs with 3-aminopropyltriethyloxysilane (APTES) and tetraethyl orthosilicate (TEOS). Herein, co-precipitation synthesis of bare IONPs and post-synthesis grafting of APTES (AIONPs) and TEOS (SIONPs) were carried out in the laboratory. Synthesis and functionalization were confirmed by examining the physical and chemical properties of the nanomaterials (NMs) using high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) analysis. The stability of the nanofluids (NFs) was examined using zetapotential and sedimentation analysis in the presence of reservoir brine (25,000ppm NaCl). The ability of the NFs to decrease interfacial tension (IFT) and alter the wettability of rock/fluid at reservoir conditions was examined using a K20 Easy Dyne Kruss tensiometer and Kruss drop shape analyzer, respectively. Based on the results, it was found that reservoir brine, decreased the electrostatic stability of IONFs, AIONFs, and SIONFs by 75.9%, 41.3%, and 68% respectively. The IFT reduction and wettability changes relative to the reference values of 25.53 ± 1.51 mN/m and 128 ± 3.4° at reservoir conditions were 11.6mN/m and 26° for IONFs, 7.7mN/m & 22.2° for AIONFs and 8.2mN/m & 15.5° for SIONFs. These findings contribute towards understanding the influence of functionalization on the oil recovery mechanism of IONPs under reservoir conditions.