Emulsion flooding has great potential for enhancing the recovery of heavy oil, especially for reservoirs in which the oil recovery by water flooding is low and thermal methods are not suitable. This study presents a study of nanoparticle-surfactant stabilized emulsion to enhance heavy oil recovery in waterflooded heavy oil reservoirs. The phase behavior tests and rheology studies were first performed to investigate the influence of nanoparticle on the stability and bulk rheological properties of the emulsion system. Then, the core flooding and microscopic visualization tests were conducted for investigating the displacement mechanisms for enhanced heavy oil recovery by nanoparticle-surfactant stabilized emulsion. The phase behavior tests and rheology studies show that the addition of nanoparticles can not only improve the stability of the emulsion, but also greatly increase the bulk viscosity of emulsion. The core flooding conducted with the emulsion co-stabilized by nanoparticle and surfactant show a marked improvement in oil recovery over the surfactant-stabilized emulsions. The tertiary oil recovery can reach over 40% of the initial oil in place (IOIP) for crude oil with the viscosity of 350 mPa•s at 50 °C. The micromodel tests indicate that the nanoparticles can thicken the emulsion to the desirable mobility, which can damp the viscous fingering phenomena to dramatically improve sweep efficiency. In addition, the heavy oil can be emulsified into the water phase to form oil-in-water emulsions with the aid of the surfactant. These results demonstrate that the nanoparticle-surfactant stabilized emulsion has a great potential for enhanced oil recovery in waterflooded heavy oil reservoirs.

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