The Influence of Breaking Waves and Photo-oxidation on the Morphology, Viscosity, and chemical composition of Water-in-Crude Oil Emulsions*

This study examines the time evolution and effect of photo-oxidation on the microscopic morphology, viscosity, viscoelasticity, and chemical composition of water-in-crude oil emulsions formed by the impact of breaking waves on 2 mm thick oil slicks. Emulsions involving Alaskan North Slope (ANS) and Hibernia, both light crude oils, and Cold Lake oil, a diluted bitumen, form by exposure to periodic plunging waves for 12 days. Samples are analyzed using Rheometry, microscopy, and chemical fingerprinting. ANS emulsifies water faster than Hibernia, resulting in higher concentration of water droplets and a more interconnected structure. Hence, the non-Newtonian viscosity of ANS emulsion is at least 3 times higher than that of Hibernia. Cold Lake emulsified by waves has double the water content compared to emulsions created by mixing in a flask at similar energy level, resulting in higher viscosity. Photo-oxidation of Hibernia accelerates the emulsification and formation of droplet clusters, and increases the water volume, hence the viscosity. It also reduces the droplet sizes and increases the biomarker concentration. For the first 4 days, photo-oxidation increases the concentration of alkylated PAHs and aromatic compounds, which increase the toxicity. They decrease in later days.