Stability and demulsification of petroleum emulsions

Abstract

Petroleum is predominantly recovered in form of W/O-emulsions which are stabilized by petroleum resins and asphaltenes, colloidal disperse components of petroleum. Both of these substances are polydisperse, resoluble, oleophilic micellar colloids, ocurring in dilutions in spherical form. In concentrated solutions, however, they form larger, inter-micellar structures. These structures generally form with the enrichment of resins and asphaltenes at oil/water interfaces.

Petroleum emulsions are stabilized by “thick films” according to Gibbs which are composed from different petroleum-internal tensides and have a Gibb’s elasticity. The more the interfacial activities of the components differ from each other, the higher is the elasticity module of the multi-component films.

We found optically anisotropic interface films in petroleum emulsions. The observed structure-formation in interface films of emulsions which are mostly stabilized by petroleum resins, increases continuuously with raising temperature. Even isolated petroleum resins in volume-phases show such a structure-formation. Lyotropic, liquid-crystalline mesophases develop. This proves that the “enhanced emulsion stability” according to Friberg is valid for petroleum resins as multi-component systems as well.

The demulsification of emulsions after addition of demulsifiers as a result of a shift of the balance lyophilic-lyophobic is being discussed.