Influence of Surface Modification on the Oil Recovery of Iron Oxide Nanoparticles Under Reservoir Conditions

Iron oxide nanoparticles (IONPs) show promise as advanced materials for enhanced oil recovery (EOR) due to their distinct physicochemical properties. However, their tendency to quickly clump together in reservoir brine, driven by the need to reduce high surface energy, poses a significant challenge. This aggregation results in reduced stability and the loss of desirable properties, ultimately impeding effective oil recovery. This study addresses these challenges by examining how functionalizing IONPs with 3-aminopropyltriethyloxysilane (AIONPs), tetraethyl orthosilicate (SIONPs), and a combination of both (ASIONPs) enhances their physicochemical characteristics to facilitate oil recovery in reservoir conditions. The nanoparticles were synthesized and modified in the laboratory, with confirmation of synthesis and functionalization achieved through analyses using high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and Thermogravimetric analysis (TGA). To accurately simulate reservoir conditions, actual reservoir cores and high-temperature, high-pressure (HTHP) core flooding equipment were used to evaluate the oil recovery of the resulting nanofluids (NFs). Visual sedimentation investigations of NPs in distilled water, low and high electrolyte concentrations revealed that APTES functionalization of IONPs and SIONPs reduced sedimentation of IONPs in the reservoir, especially in high electrolyte conditions. Under reservoir conditions (25,000 ppm, 2400Psi, 120°C), the respective oil recovery percentages for ASIONFs, SIONFs, AIONFs, and IONFs were found to be 14.6%, 13.8%, 18.3%, and 4.8%. These comprehensive findings significantly contribute to our understanding of how functionalization influences the oil recovery efficiency of IONPs in reservoir settings.