Viscosity behavior for zirconia and γ-alumina nanoparticles in different electrolytic solutions: An experimental investigation

Viscosity modification of injected fluids is a vital mechanism for successful oil recovery from an oil reservoir. Various studies have demonstrated that nanoparticles (NPs) possess the tendency to alter the wettability of reservoir rocks, reduce the interfacial tension between injected fluids and crude oil, and modify the viscosity of injected fluids. Zirconia (ZrO2) and gamma-alumina (gamma-Al2O3) NPs have demonstrated huge prospects for enhanced oil recovery (EOR) in various studies. Recently, experimental investigations have attributed the viscosity behavior of silica nanofluids to the interaction between the ions of the silica NPs and electrolytes at the electrical double layer. Therefore, this study investigates the viscosity behavior of ZrO2 and gamma-Al2O3 NPs with their increasing concentrations in different aqueous solutions present in reservoir brine by employing techniques such as dynamic light scattering and transmission electron microscopy in addition to viscosity and pH measurements at ambient conditions of approximately 25celcius and 1 atm. The viscosity behavior of spherical particles in suspensions is well suited for the viscosity profile of the nanofluids with increasing concentrations of ZrO2 and gamma-Al2O3 NPs. The viscosity of the ZrO2 and gamma-Al2O3 nanofluids containing the chloride salts increases in the order of Ca2+ > Na+ > K+ while those containing the sulfate salts increase in the order Mg2+ > Na+ > K+. Comparatively, the model proposed by Williams et al. predicts the viscosities of the electrolyte-based zirconia and gamma-Al2O3 nanofluids with percentage absolute average deviation (%AAD) of 2.07 and 2.52 %, respectively, whereas those by Einstein's model records %AAD of 3.15 and 3.68 %, respectively. The findings from this study provide experimental data and illuminate the understanding of the viscosity behavior of the nanofluids containing electrolytic ions and set the stage for further investigations, which are relevant for EOR purposes.

Automated summary

Viscosity modification of fluids injected into oil reservoirs is crucial for successful oil recovery. This study investigates the viscosity behavior of ZrO2 and gamma-Al2O3 nanoparticles (NPs) in different aqueous solutions. The results show that the viscosity of the nanofluids increases with the concentration of NPs, and the type of electrolytic ions in the solution affects the viscosity behavior. The proposed model by Williams et al. predicts the viscosities of the nanofluids more accurately compared to Einstein's model.