EMULSIONS STABILIZED BY PETROLEUM NATIVE PARTICLES: FROM NANO TO MICRO-SCALE

Interface-active compounds naturally occurring in crude oils contribute to
the inevitable formation of water-in-oil emulsions.1 Several efforts have been made to correlate crude oil's composition and emulsification tendency, but this sometimes does not correctly explain the differences in emulsion stability. We hypothesize that it also depends on the colloidal structure of the oils. In this study, we separated three different crude oils into fractions to elucidate their structures using optical microscopy, DLS, and SAXS. Then, we evaluated the influence of these structures on the formation, stability, and rheology of water-in-oil emulsions.
The characterization of oil fractions revealed that wax microcrystals and asphaltene nanoaggregates act as the main emulsion stabilizers. Rheology measurements showed that the presence of wax crystals increases the viscoelasticity of emulsions due to the formation of networks but decreases the thermal stability. Pickering emulsions stabilized by asphaltene nanoaggregates are less viscoelastic but thermally stable. Results also showed that emulsions could be destabilized by disturbance or removal of these nano/micro-structures. This finding will allow proposing of new strategies to mitigate the problems related to petroleum emulsions.