Microwave radiation to promote the destabilization of water-in-crude oil petroleum emulsions is already an alternative technology for heating. Recent studies have suggested that microwave heating is more effective than conventional heating. This study assessed the following effects on the demulsification process: the aging of emulsions for the two types of heating (microwave and conventional), the time interval between microwave heating and the addition of a chemical demulsifier, and the time of microwave irradiation on the heating of petroleum and brine fluids. In addition, this study compared the efficiency of water separation by conventional heating and microwave heating regarding the (a) mean temperature of the emulsion and (b) temperature of water droplets. It was observed that water separation is less efficient for the two types of heating when the emulsion is subjected to aging. The efficiency of water separation using microwave heating is greater than with conventional heating when the mean temperature of the emulsion remains the same. However, they were equivalent when the temperatures of the water droplets are equal. This fact indicates that the advantage of selectively heating water droplets by microwave radiation is that the temperature of the treatment of emulsions can be reduced: the higher temperature that is located in region of interest (water droplets and the periphery) facilitates the drainage of the interfacial film and the stage of coalescence between the water droplets.

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Three different macromolecular structures of poly(ethylene oxide-b-propylene oxide) copolymers, used in formulations of commercial demulsifiers for breaking water-in-crude oil emulsions, were investigated. The interfacial activity (), the lower interfacial tension (m), the critical micelle concentration (CMC), the interfacial concentration (Γ) and the molecular area (A) adsorbed at the interface of the surfactant solutions were evaluated. These results were correlated to surfactant performance in coalescing three different asphaltene model emulsions. The PEO-b-PPO commercial demulsifiers, that were capable to dewater asphaltene model emulsions, exhibited interfacial activity to the oil-water interface, reduced the interfacial tension to low values, reached the CMC at low concentration and presented low molecular area adsorbed at the interface.

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Foams generated during oil production are complex systems. The complexity of their continuous phase makes it difficult to understand what occurs in the foam layers. Some studies have shown that the main species that stabilize foams are asphaltenes, because they reduce the surface tension of the bubbles with their interfacial activity, causing this surface to become viscoelastic. To understand surface viscoelasticity, it is necessary to investigate the rheology of the crude oil/air interface. Since the great majority of works published have used a Du Noüy ring or BiCone accessory to evaluate the surface only of model asphaltene systems, the aim of this work is to study the crude oil/air interface of different crude oil samples and different antifoaming products using the BiCone accessory.