Nanofluid Enhanced Oil Recovery Using Hydrophobically Associative Zwitterionic Polymer-Coated Silica Nanoparticles

Abstract

Intense interest has been shown in the, development:of "smart nanofluids" because they can dramatically change their flow properties in complex fluid systems. We introduce a robust and straightforward approach to develop a smart nanofluid system, in which associative Silica nanoparticles (ASNPs) were incorporated to regulate their flow properties in rock pores. ASNPs were synthesized by covalently coating a hydrophobically associative hygroscopic zwitterionic poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-cc-divinylbenzene (DVB)], shell layer on 20 nm sized silica nanoparticles (NPs) by surface-mediated living radical polymerization, The essence of our approach is to copolymerize DVB, which endows the polymer shell of ASNPs with a weak long-range hydrophobic attraction. This leads to the favorable formation of a wedge film as a result of Structural disjoining pressure. This wedge filth made the oil adsorbed on the rock surface more dewettable, thus enhancing the efficiency of oil recovery. As,a result of this unique behavior,: the ASNP nanofluid developed in this study remarkably improved the fluidity of complex oil fluids; similar to 5 vol % oil recovery enhancement and similar to 0.3 psi pressure reduction were also achieved in comparison to neat, nanofluid controls.