Effects of silica-based nanostructures with raspberry-like morphology and surfactant on the interfacial behavior of light, medium, and heavy crude oils at oil-aqueous interfaces

Any efficient exploitation of new petroleum reservoirs necessitates developing methods to mobilize the crude oils from such reservoirs. Here silicon dioxide nanoparticles (SiO 2 NPs) were used to improve the efficiency of the chemical-enhanced oil recovery process that uses surfactant flooding. Specifically, SiO 2 NPs (i.e., 0, 0.001, 0.005, 0.01, 0.05, and 0.1 wt%) and Tween ® 20, a nonionic surfactant, at 0, 0.5, and 2 critical micelle concentration (CMC) were varied to determine their effect on the stability of nanofluids and the interfacial tension (IFT) at the oil–aqueous interface for 5 wt% brine-surfactant-SiO 2 nanofluid-oil systems for West Texas Intermediate light crude oil, Prudhoe Bay medium crude oil, and Lloydminster heavy crude oil. Our study demonstrates that SiO 2 NPs may either decrease, increase the IFT of the brine-surfactant-oil systems, or exhibit no effects at all. For the brine-surfactant-oil systems, the constituents of the oil and aqueous substances affected the IFT behavior, with the nanoparticles causing a contrast in IFT trends according to the type of crude oil. For the light oil system (0.5 and 2 CMC Tween ® 20), the IFT increased as a function of SiO 2 NP concentration, while a threshold concentration of SiO 2 NPs was observed for the medium (0.5 and 2 CMC Tween ® 20) and heavy (2 CMC Tween ® 20) oil systems in terms of IFT trends. Concentrations below the SiO 2 NP threshold concentration resulted in a decrease in IFT, and concentrations above this threshold resulted in an increase in IFT. The IFT decreased until the NP concentration reached a threshold concentration where synergetic effects between nonionic surfactants and SiO 2 NPs are the opposite and result in antagonistic effects. Adsorption of both SiO 2 NPs and surfactants at an interface caused a synergistic effect and an increased reduction in IFT. The effectiveness of the brine-surfactant-SiO 2 nanofluids in decreasing the IFT between the oil-aqueous phase for the three tested crude oils were ranked as follows: (1) Prudhoe Bay > (2) Lloydminster > and (3) West Texas Intermediate. The level of asphaltenes and resins in these crude oil samples reflected these rankings. A decrease in the IFT also indicated the potential of the SiO 2 NPs to decrease capillary pressure and induce the movement and recovery of oil in original water-wet reservoirs. Conversely, an increase in IFT indicated the potential of SiO 2 NPs to increase capillary pressure and oil recovery in reservoirs subject to wettability reversal under water-wet conditions. Raspberry-like morphology particles were discovered in 5 wt% brine-surfactant-SiO 2 nanofluid-oil systems. The development of raspberry-like particles material with high surface area, high salt stability, and high capability of interfaces alteration and therefore wettability changes offers a wide range of applications in the fields of applied nanoscience, environmental engineering, and petroleum engineering.