The formation of “chocolate mousse” from Statfjord crude oil and seawater

Physical factors affecting the formation of water-in-oil emulsions (‘chocolate mousse’) from crude Statfjord oil was investigated in the laboratory. Irradiation by visible light and mechanical agitation are shown to be essential. It is suggested that photochemical oxidation of oil components leads to the formation of surface-active, oil-soluble compounds. When these reach a sufficient concentration in the oil, water will be retained within the oil during physical mixing. The plausibility of such a mechanism is investigated further using additions of tetradecanal as an oil-soluble, surface-active agent and β-carotene as an inhibitor of photooxidation. The use of additives to stop ‘mousse’ formation is suggested.