Stability and demulsification characteristics of Pickering emulsions under an electric field

The stability characteristics of a Pickering emulsion and its demulsification behavior under an electric field were demonstrated experimentally, providing a data foundation for nanofluid displacement in enhanced oil recovery processes. The results showed that the stability of Pickering emulsions increased with the increase of particle concentration, and the average size of the emulsion droplets gradually decreased, which could increase apparent viscosity of Pickering crude oil emulsion by approximately 30%. Under alkaline conditions, nanoparticles were more likely to aggregate, and the aggregated particle clusters were not easily adsorbed on the oil–water interface, resulting in a decrease in the emulsion stability. When the particle concentration varied within the range of 0–1.25%, the electric field demulsification and dehydration rate gradually decreased, and the decreasing speed of dehydration rate slowed down. The presence of nanoparticles improved the stability of the emulsion, and even low-concentration nanoparticles would significantly reduce the effect of electric field demulsification and dehydration. Alkaline environment, especially strong alkaline environment, had a good promoting effect on demulsification and dehydration. When pH = 12, the dehydration rate could be increased by about 23.1%. Alkaline environment was more conducive to the demulsification and dehydration of Pickering crude oil emulsion.