Dispersion of High Viscosity Oils

ABSTRACT This study evaluated the effectiveness of three dispersants in simulated seawater on five different fuel oils (both intermediate fuel oils (IFOs) and heavy fuel oils (HFOs)) with viscosities ranging from 1,079 to 6,615 cSt and densities ranging from 0.995 to 0.998 g/cc. The three dispersants were COREXIT® 9500 dispersant, a dispersant under development by ExxonMobil – ED-6™ gel dispersant, and FINASOL™ OSR 52 dispersant. Testing was done at two dispersant-to-oil ratios (DOR) – 1:20 and 1:10. All three dispersants were effective (70%+ dispersant effectiveness (DE)) for fuel oils with a viscosity less than 2,000 cSt - IFOs 180 and 380. The dispersants were less effective (16 to 58% DE) for the higher viscosity oils (ranging in viscosity from 4,258 to 6,615 cSt). Increasing the amount of dispersant from a DOR of 1:20 to 1:10 significantly improved DE. For example, the DE of the two HFOs studied increased from less than 42% to greater than 56% using COREXIT 9500™ dispersant. The results of our bench-scale study indicate that dispersants can disperse heavy fuel oils and, therefore, could be a response option for spills of these products in a marine environment.