Foams Enhanced by Functionalized Nanoparticles for Improving Oil Production

Abstract

This study presents an experimental study on the foams enhanced by functionalized nanoparticles with improved colloidal stability in a high salinity brine facilitates the foam generation and stability in applications to improve oil recovery. An anionic surfactant was selected as the foaming agent. Silica nanoparticles were grafted with binary ligands to achieve both salt tolerance and surface activity. Solutions were prepared in 1 g/L sodium chloride and a high salinity water with total dissolved solids of 57 g/L, respectively. The properties of solutions were characterized in terms of surface tension, viscosity and zeta-potential. Bulk nitrogen foam stability was analyzed through morphology of bubble sizes. Moreover, the effectiveness of foam flow to improve oil dis-placement in porous media was verified in microfluidic tests. The reduced surface tension and neutralized zeta potential indicated strong adsorption and dense packing of the functionalized nanoparticle at the air-water interface, which was further enhanced under higher salinity due to the screened electrostatic repulsion. The foam stability was significantly improved in presence of the nanoparticle, shown as ~50% smaller bubble size 1 h after foam generation, compared to the case with surfactant only. The adsorption of surface-active nanoparticles at the gas-water interface strengthened the lamella against coalescence, while the higher elasticity of the interface inhibited coarsening. High displacement efficiency of oil over 85% with foams was validated through microfluidic tests. The clarified effect of salinity on foam performance could be of significant benefit in the selections of surface-active agents for applications of foams to increase oil recovery.