Methods and compositions for recovery of residual oil from a porous structure

Abstract

The methods disclosed herein allow for the recovery of at least 55% of residual heavy oil from porous structures. In the disclosed methods, porous structures are contacted with emulsions having an aqueous continuous phase and an organic dispersed phase. The organic dispersed phase includes organic compounds having five or fewer carbon atoms (such as natural gas), which are typically difficult to emulsify because they are unstable at ambient conditions. To solve that problem, the emulsions disclosed herein are stabilized by nanoparticles having hydrophilic exterior surfaces. The nanoparticles make up at least 0.1% of the emulsion by weight. The use of hydrophilic nanoparticles as stabilizers combines the utility of natural gas liquids in enhanced oil recovery (due to their high solubility in residual oil and attendant viscosity reduction) with the utility of emulsions (delivery of viscosity-reducing agents along with an immiscible phase to push out the trapped oil).

Dependencies are inferred from the claim text.