3D pore-scale modeling of nanofluids-enhanced oil recovery

The numerical modeling of oil displacement by nanofluid based on three-dimensional micromodel of cores with different permeability was carried out by the volume of fluid (VOF) method with experimentally measured values of interfacial tension, contact angle and viscosity. Water-based suspensions of SiO2 nanoparticles with a concentration of 0–1% and different particle sizes were considered to study the effect of concentration and size of nanoparticles, displacement fluid flow rate, oil viscosity and core permeability on the efficiency of oil displacement by nanofluid. The oil recovery factor (ORF) increases with the increase of mass fraction of nanoparticles. An increase in nanoparticles' concentration to 0.5% allows an increase in ORF by about 19% compared to water flooding. The ORF increases with the decrease of nanoparticle size, and declines with the increase of displacing rate. It has been shown that the use of nanosuspensions for enhanced oil recovery is most effective for low-permeable reservoirs with highly viscous oil in injection modes with capillary number close to the immobilization threshold, and the magnitude of oil recovery enhancement decreases with the increase of displacement speed. The higher the oil viscosity, the lower the reservoir rock permeability, the higher the ORF improved by nanofluids will be.