Study of the influence of commercial demulsifiers on the water/oil interface: interfacial tension and viscoelastic properties of the interfacial film

During the production and transportation of petroleum, the formation of emulsions is common, especially the water-oil type, as a result of vigorous agitation of these phases when subjected to high shear and turbulence conditions. However, in this scenario, the stability of emulsions is undesirable because affect the performance of electric submersible pumps (ESP or Electrical Submersible Pump) and the flow of fluid through the production lines. The kinetic stability of oil emulsions depends on the formation of the molecular/oil interface and its physical properties. These factors are highly dependent on the characteristics of the species adsorbed at the interface which are asphaltenes, resins, naphthenics acids and demulsifiers occasionally injected in production system. In order to understand the relationship between the stability of water-oil emulsions and the properties of the oil/water interface, the general objective of this project is to evaluate how a commercial demulsifier can affect the characteristics of the interfacial film, allowing to establish correlations between the properties of the film and efficiency of surfactants, seeking a microscopic understanding of separation water-oil emulsions. For this, the study was focused on dilatational interfacial rheology techniques of systems composed of crude oils and their respective produced water, extracted from two wells located in Campos Basin. In this study, the phase separation kinetics were analyzed using the Bottle Test. The results obtained indicate that the demulsifier reduced the interfacial tension to values as low as 1 mN/m. The same trend was observed for the dilatational rheological properties. These results allow establishing a correlation between the interface parameters and the efficiency of the demulsifier, highlighting the characteristics of the interfacial film as possible parameters to be evaluated in the development and/or testing of demulsifiers for application in the field (AU)