Evaluating crude oil distribution tendencies in a multi-phase aquatic system: Effects of oil type, water chemistry, and mineral sediment

Abstract

Planning for effective response to crude oil spills into water depends on evidence of oil behavior, including its tendency to become distributed throughout an aquatic system. An improved laboratory method is employed to quantitatively assess crude oil distribution among different layers that form after mixing within a multi-phase system of water and sediment. Mixtures of conventional crude oil or diluted bitumen with different water types in the presence or absence of mineral sediment are first mixed by a standard end-over-end rotary agitation protocol. After a settling period, each mixture's visibly distinct floating, surface oil (e.g., slick or emulsion), subsurface bulk water, and bottom layers are then separated. Finally, the masses of oil, water, and sediment constituting each layer are isolated, quantified, and compared. The novel results reveal how component properties affect oil distribution among layers to inform spill behavior models, risk assessments, and response plans, including applications of spill-treating agents.

Keywords: Aquatic environment; Crude oil spill; Fate and behavior; Oil-in-water dispersion; Oil-particle aggregate; Water-in-oil emulsion.