A numerical study of silica sol flow regimes during oil displacement from the models of porous media

The present work reports the results of a systematic numerical investigation of displacement flows during oil recovery from models of terrigenous and fractured porous media using silica nanoparticle-based nanofluids. In the calculations, nanofluids with a mean particle size of 10 nm were considered, with the mass concentration of particles varied within the range of 0.25–1.0 wt. %. The nanofluid properties required for the simulations were preliminarily determined through experimental studies. The effects of nanoparticle concentration, pore-space structure, capillary number, and displaced oil viscosity on flow regimes and displacement efficiency were examined. A relationship was established between the physicochemical properties of the investigated nanofluids and the oil displacement characteristics in the model porous media. The key factors are identified as improved wettability and reduced interfacial tension upon nanoparticle introduction. It was demonstrated that an increase in nanoparticle concentration leads to a higher oil displacement coefficient for both reservoir models. Moreover, the efficiency of nanofluid application is substantially enhanced with increasing oil viscosity and decreasing capillary number.