Recent studies of Pickering emulsion system in petroleum treatment: The role of particles

Pickering emulsions stabilized by solid particles have gained much attention, which afford high stability, low toxicity, controllable rheological properties and stimuli-responsive behavior compared to the traditional emulsions emulsified by surfactants. Those particles, as the core parts of the emulsion systems, play an important role in the fabrication and application of Pickering emulsion systems, making them attractive in petroleum fields. In this review, the influence of various particles on the stability and properties of Pickering emulsion systems as well as recent researches associated with the stimuli-responsibility of Pickering emulsion systems are introduced. Specifically, the design of functional particles and Pickering emulsion systems with super stabilities and controllable rheological properties are listed. Furthermore, some petroleum application of Pickering emulsion systems for enhanced oil recovery and spilled oil collection as well as the application as soft templates to fabricate oil-absorbing material and as three-phase microreactors that most likely for petroleum application are discussed, and the issues hindering the actual application of Pickering emulsion systems are also evaluated. This review charts a way for Pickering emulsion studies that could lead to a valid petroleum application through design of the particles served as the enhancers of Pickering emulsion stability for purpose of tailoring chemical flooding.