The potential applications in oil recovery with silica nanoparticle and polyvinyl alcohol stabilized emulsion

Abstract

We investigated the use of silica nanoparticle-stabilized emulsions to displace oil in porous media. A low-quality (20%) n-decane-in-water emulsion was injected into a glass-bead pack containing mineral oil under residual oil saturation conditions. Continuous injection of the emulsion caused steady trapping and accumulation of emulsion droplets, which occurred despite the fact that the bead sizes were 250-500 mu m, whereas the average droplet size was similar to 30 mu m, as indicated by particle size analysis. By alternately injecting small banks of emulsion (0.1 pore volume (PV)) and water (0.23-0.1 PV), the extent of emulsion droplet trapping could be controlled while achieving oil recovery. The effects of salt addition and polyvinyl alcohol (PVA)/nanoparticle concentration were also investigated in terms of emulsion stability and oil recovery. The salt addition (1 wt%) more efficiently stabilized the droplets without significant coalescence and contributed to approximately 4% more oil recovery than achieved in the absence of an emulsion system. The PVA/nanoparticle concentration indicated that the emulsion with a low concentration (0.05 wt%) of PVA and a high concentration (3 wt%) of nanoparticles had greater stability and enhanced oil recovery compared with the opposite (a high concentration (0.2 wt%) of PVA and low concentration (1 wt%) of nanoparticles). These results indicated that the addition of salt and PVA/nanoparticle concentration influenced oil recovery and emulsion stability. Oil recovery was related to emulsion stability.