Crude oil emulsion: A review on formation, classification and stability of water-in-oil emulsions

The principal objective of this review paper is to review the current state of understanding in the formation, classification and stability of crude oil emulsification. In the oil and gas industry, emulsions formation in the pipeline is unwanted as emulsions will have negative effects or problems to the field. The presence of emulsions in the crude oil will reduce the quality of the crude itself, increase the operating cost due to emulsions separation as well as cause of corrosion to the transport system and will contaminate catalyst used for the refining process. Since emulsions bring numerous disadvantages to the oil and gas industry, it is important to review on the formation of emulsions so that the research gaps in the emulsification field can be discovered and hence the preventive measures can be investigated or introduced. This review paper is focused on water-in-crude oil emulsion only because water-in-oil emulsion is regularly occurring in the oil and gas industries.