Key Parameters Affecting the Dispersion of Viscous Oil

Abstract

ABSTRACT Oil viscosity has been perceived as a major factor affecting the dispersibility of oil. Very high viscosity oils—20,000 centistokes (cs) or more—can readily be observed as resisting the breakup of the oil into dispersed droplets. However, there are instances where a relatively viscous oil will disperse much more readily than another oil of similar viscosity. An extensive study has been conducted at ExxonMobil Research facilities in New Jersey to define the molecular makeup of 14 viscous heavy fuel oil products and determine the property of the viscous oils, besides viscosity, that influences dispersibility. Dispersibility was measured by a standard laboratory dispersant test using a COREXIT dispersant selected from the U.S. Environmental Protection Agency (EPA) National Contingency Plan (NCP) Product Schedule. Initially, IATROSCAN (TLC) and gas chromatography data failed to show any correlation between chemical properties, such as sulfur, aromatics, paraffins, resins, vanadium, nickel content, etc., and dispersibility. However, the analysis did identify a statistically significant relationship between a parameter based on normal paraffin content and dispersibility, which helps explain anomalies such as low viscosity oils that do not disperse. These results are expected to aid in guiding oil spill response for viscous oils.