THE EFFECT OF CRUDE OIL COMPOSITION ON DISPERSANT PERFORMANCE

ABSTRACT Previously, anomalous results from various laboratory dispersant effectiveness tests were believed due to the historic difficulties of replicating field conditions in the laboratory. Some variables were reported to cause differences in dispersant performance, such as the oil viscosity—i.e., both dispersant A and dispersant B exhibited poorer performance as the oil viscosity increased. Other test results showed an opposite trend. For example, dispersant A performed more effectively than dispersant B for Murban crude oil but B was better than A for the more viscous La Rosa crude oil. It is now believed that these inconsistent results are actually due to the chemical compositions of the crude oils. Various factors influence dispersant performance and some initial research directed at determining the mechanism of water-in-oil emulsion (mousse) formation has identified naturally occurring surfactants in the various crude oils. This will provide insight as to how these indigenous agents interacted with the surfactant package in the test dispersant to affect overall performance. Variations in dispersant performance for different crude oils are thus likely to be related to the water-in-oil emulsion formation of the particular crude oil. The results of this work indicate that dispersant treatment should be evaluated during spill situations even if the crude oil physical properties, such as high viscosity, might suggest that dispersant treatment would not be effective.