An Overview of Recent Advances in State-of-the-Art Techniques in the Demulsification of Crude Oil Emulsions

Abstract

The processing of crude oil often requires the extraction of a large amount of water. Frequently, crude oil is mixed with water to form water-in-crude oil emulsions as the result of factors such as high shear at the production wellhead and surface-active substances that are naturally present in crude oil. These emulsions are undesirable and require demulsification to remove the dispersed water and associated inorganic salts in order to meet production and transportation specifications. Additionally, the demulsification of these crude oil emulsions mitigates corrosion and catalyst poisoning and invariably maximizes the overall profitability of crude oil production. Recently, there has been growing research interest in developing workable solutions to the difficulties associated with transporting and refining crude oil emulsions and the restrictions on produced water discharge. Therefore, this paper reviews the recent research efforts on state-of-the-art demulsification techniques. First, an overview of crude oil emulsion types, formation, and stability is presented. Then, the parameters and mechanisms of emulsification formation and different demulsification techniques are extensively examined. It is worth noting that the efficiency of each of these techniques is dependent on the operating parameters and their interplay. Moreover, a more effective demulsification process could be attained by leveraging synergistic effects by combining one or more of these techniques. Finally, this literature review then culminates with propositions for future research. Therefore, the findings of this study can help for a better understanding of the formation and mechanisms of the various demulsification methods of crude oil to work on the development of green demulsifiers by different sources.

Applying ultrasonic fields to separate water contained in medium-gravity crude oil emulsions and determining crude oil adhesion coefficients

“…Several advantages of ultrasonic methods have been reported by researchers. One of the advantages of ultrasonic methods is the reduction of the emulsification time and the formation of smaller droplets compared with that generated by the conventional method [15] , [38] . The beneficial effects of ultrasonic waves on crude oil viscosity were previously recognized by Abramov et al [39] .…”

“…Based on the ultrasonic pilot-plant studies, ultrasonic fields also offer the potential to be used to continuously separate water droplets in crude oil pipelines. Chemical demulsifiers are popular because they are easily applied at a reasonable cost [38] , [42] . However, applying ultrasonic methods typically increases the production cost and these methods must be improved to provide lower costs to be accepted as a replacement for chemical demulsifiers.“…”

Application of Ionic Liquids for Chemical Demulsification: A Review

“…Emulsion is produced when two or more immiscible liquids mix vigorously together which results in two phases (a dispersed phase and a continuous phase) [ 25 , 26 ]. The phase that has smaller volume is usually identified as the dispersed phase and the larger one is the continuous phase.…”

“…Surface-active chemicals (i.e., demulsifiers) are used to destabilize emulsions [ 25 , 49 ]. Some examples of common chemical demulsifiers include sodium dioctyl sulfosuccinate, sodium dodecyl sulfate, and polyethylene oxide ( Figure 2 ).…”

“…Temperature can affect the physical properties of emulsion such as viscosity. The viscosity of a continuous phase reduces at high temperatures (e.g., 70 °C) [ 98 ], which facilitates the dissolution of ionic liquids in the continuous phase [ 25 , 27 , 107 ]. Temperature should be increased up to the phase inversion temperature (PIT), at which emulsion alteration occurs (e.g., W/O turns into O/W) [ 123 ].…”