Experimental investigation and two-phase flow simulation of oil and nanofluids on micro CT images of sandstone for wettability alteration of the system

Abstract

This work provides an analysis of the effect of nanofluids on the wettability of sandstone for the application of enhanced oil recovery. The wettability of sandstone with brine and nanofluids of ZnO, BiFeO 3, and SrFeO 3 is studied experimentally using contact angle calculations. Also, the direct simulations for the displacement of oil with brine and nanofluids are carried out on a micro-CT scanned porous sandstone structure for the measurement of capillary pressure and relative permeability. Fluid properties such as viscosity and density of the nanofluids, brine, and oil to be used in simulations were obtained using viscometer and densimeter. The experimental results show that the contact angle of crude oil on the sandstone surface has a higher value for nanofluids as 125.89° for ZnO, 122.88° for BiFeO 3, and 104.98 for SrFeO 3 as compared to brine 28.66°, which means the wettability of the system changes from oil-wet to water-wet by the addition of nanofluids. The simulation results indicate that BiFeO 3 nanofluid has a greater tendency to change the wettability of porous medium as compared to brine, ZnO, and SrFeO 3 nanofluids, as it shows better values of relative permeability and capillary pressure. • Micro-CT imaging of sandstone samples and image processing is explained. • Mathematical model and boundary conditions for two-phase flow simulation are described. • Experimental calculations for fluid properties i.e. contact angle, viscosity and density. • Saturation profiles for two-phase flow of oil and brine/nanofluids are studied. • Relative permeability and capillary pressure curves are evaluated.