EFFECTS OF ASPHALTENE SOLVENCY ON STABILITY OF WATER-IN-CRUDE-OIL EMULSIONS

The formation of stable and persistent emulsions and foams in the prod uction and refining of crude petroleum is a challenge which has defied broad and generic resolution for several decades. Rational and system atic approaches to demulsification have been slow to develop due to a lack of fundamental understanding of the molecular origins of emulsion stabilization and the full range of factors which govern emulsion sta bility. Several studies have shown the importance of resins and asphal tenes, which have the ability to organize and form rigid films at the oil/water interface. We have developed a molecular model in which we p ropose that the integrity of these films and thus their ability to sta bilize water-in-crude-oil emulsions are sensitive to a variety of crud e solvency parameters, such as aromaticity, resin-to-asphaltene ratio, and polar functional group concentration. This model was tested by co rrelating the stability of emulsions formed from a variety of crude oi ls-Arab Berri (Extra Light), Arab Heavy, Alaska North Slope, and San J oaquin Valley-in which the resin and asphaltene contents vary, as well as their specific characteristics. The results of the elemental and f unctional group characterization of these crudes and their fractions a nd the techniques utilized to obtain them were presented previously. D etailed quantitative protocols for gauging relative emulsion stability have been developed to further evaluate the proposed model by blendin g solvents of varying aromaticity and by doping isolated resins from d ifferent crudes into solvent-modified crudes. Dramatic destabilization of emulsions was accomplished by modifying the crude solvency in eith er fashion. Simple physical and chemical techniques for minimizing emu lsion formation such as basic crude blending and solvent-recycle schem es will also be discussed.