Our current understanding of water-in-crude oil emulsions.: Recent characterization techniques and high pressure performance

Stable water-in-oil emulsions may form during the production of crude oil, as co-produced water is mixed with the oil from reservoir to separation facilities. Such emulsions introduce technical challenges, as they must be resolved to provide the specified product quality. Asphaltenes and resins indigenous to the oil are acknowledged as the most important components in respect to stabilization of the interface against coalescence. Fine solids may also contribute to the stabilization, as may the presence of naphthenic acids. Combined, this creates a complex picture of several contributing mechanisms, and it is established that the pressure conditions will influence the behavior of active components and the properties of the interface. In order to successfully mitigate the problems of stable emulsions, a thorough knowledge of component properties, behavior, interactions and effect on water/oil interfacial properties must be developed for pressures ranging from ambient to high. This review seeks to bring to light recent findings related to these topics.