Polymer-Functionalized Nanoparticles for Improving Waterflood Sweep Efficiency: Characterization and Transport Properties

Water-dispersible polymer–silica nanocomposite particles, SiO2–ethylene oxide-based polymer nanoparticles hybrids, were synthesized using a “grafting-from” method, where polymer brushes were grown on silica nanoparticles using living radical polymerization. Water-soluble polymer chains were grown from initiator-tethered 15-nm silica nanoparticles with ∼600 chains grafted per nanoparticle, resulting in a surface grafting of ∼1 chain per square nanometer. The single-phase and multiphase transport properties of low concentration brine dispersions of these polymer nanoparticles hybrids through a Berea sandstone core were measured. Experiments show that, while the viscosity increase is modest for dispersions with concentrations of 0.5–2 wt % of the nanoparticle hybrid, the dispersions were able to transport without hindrance through the porous media and, furthermore, were found to be effective at mobilizing waterflood residual oil.