DISPERSANT EFFECTIVENESS TESTING ON VISCOUS, U.S. OUTER CONTINENTAL SHELF CRUDE OILS AND WATER-IN-OIL EMULSIONS AT OHMSETT

Abstract

ABSTRACT Two separate projects were funded by the US Minerals Management Service to study the dispersibility of viscous crude oils and water-in-oil emulsions. The objective of the first study was to determine the viscosity limit for the effectiveness of chemical dispersants applied to viscous US Outer Continental Shelf crude oils of varied origin. The objective of the second study was to determine the effectiveness of chemical dispersants when applied to water-in-oil emulsions and to determine if similar viscosity limits exist for successful dispersion of emulsions as for non-emulsified crude oils. In both programs, preliminary tests were completed in the small-scale wave tank at SL Ross. Full-scale tests were completed at The National Oil Spill Response Test Facility (Ohmsett) in Leonardo, New Jersey in April 2005 (viscous oils) and December 2005 (emulsions). In the emulsion dispersion program, tests were conducted with both Corexit 9500 and Corexit 9527 dispersants. Only Corexit 9500 was used in the viscous oil dispersion testing. In the viscous oil test program, the effectiveness of the dispersant was influenced by both oil type (viscosity) and to a lesser extent by DOR. In general, the oils with viscosities lower than 6,500 cP were dispersible to a significant degree, whereas the oils with viscosities of 33,000 cP and greater were not. Oils between 6,500 and 33,000 cP were not available for testing to identify dispersant effectiveness between these two viscosities.