Carbon dioxide-in-oil emulsions stabilized with silicone-alkyl surfactants for waterless hydraulic fracturing.

The design of surfactants for CO/oil emulsions has been elusive given the low CO-oil interfacial tension, and consequently, low driving force for surfactant adsorption. Our hypothesis is that waterless, high pressure CO/oil emulsions can be stabilized by hydrophobic comb polymer surfactants that adsorb at the interface and sterically stabilize the CO droplets. The emulsions were formed by mixing with an impeller or by co-injecting CO and oil through a beadpack (CO volume fractions (ϕ) of 0.