(85g) Nanoparticle Stabilized High Internal Phase CO2-in-Water Foams: Effects of Surfactants and Polymers
Chemical formulations of nanoparticles and surfactants are developed to stabilize high internal phase carbon dioxide-in-water (C/W) foams for low water hydraulic fracturing fluids. Silica nanoparticles and low concentrations of surfactants that weakly interact with nanoparticles were used to stabilize the C/W foams. The surfactants are adsorbed onto the nanoparticles to influence the contact angle of the nanoparticles to stabilize the dispersed CO2 phase droplets against coalescence. Also, the free surfactants reduce the interfacial tension between the aqueous phase and CO2 phase to facilitate the break-up of the CO2 phase into bubbles. The ability to achieve stable high internal phase C/W foams with properly designed nanoparticles could offer an alternative to conventional surfactants to raise the foam stability to be adequate for hydraulic fracturing operations. Further, water-soluble polymers were demonstrated to greatly improve the viscosities of the C/W foams. The ability to generate viscous fluids with low amounts of water for fracturing of shale reservoirs is of great interest for both reducing global water utilization and mitigation of post-processing of contaminated fracturing fluids.