Formation, stabilization and chemical demulsification of crude oil-in-water emulsions: A review

The crude oil recovery process is frequently associated with the formation of stable emulsions due to factors such as turbulent flow in pipelines and the presence of surface-active substances that naturally occur in crude oil. These emulsions are undesirable for the petroleum industry because their destruction/treatment adds to the overall production cost and causes the loss of valuable amounts of crude oil. Therefore, it is essential, for economic and environmental reasons, to optimize the crude oil demulsification process. The effective treatment of crude oil emulsions requires understanding of the process and factors leading to their formation and stabilization. In this sense, suitable treatment methods and possible preventive measures to avoid their formation can be employed. The present study reviews recent oilfield emulsion types and the factors responsible for their formation and stabilization. The different demulsification techniques employed were then extensively examined. Demulsification techniques include mechanical, thermal, electrical, and chemical methods with different demulsification mechanisms affected by many factors such as emulsions type and properties, demulsifiers characteristics, presence of solids stabilized emulsions, etc. The demulsification efficiency depends on the operating parameters of the process, the economics involved, and the environmental impact, which are the main factors considered in selecting a suitable demulsification technique. Future research on the demulsification of crude oil emulsions should focus on real crude oil emulsions studies at a pilot scale level, the effect of aging on crude oil emulsions, the combination of multiple demulsification techniques and their synergistic effects, and the use of natural, ecofriendly demulsifiers.