Formation and characterization of water-in-oil emulsions: insights from simulated mesoscale oil spill tests

Abstract Transporting oils across Canada via pipelines, rail, and tankers poses environmental risks from potential spills into waterways. Understanding how oil properties and environmental conditions influence the formation and stability of weathered water-in-oil (w/o) emulsions is critical. This study examines the spill behaviors of five oils—Hibernia Crude (HC), Alaska North Slope (ANS), Diluted Bitumen (Dilbit), Very Low Sulfur Fuel Oil (VLSFO), and Point Arguello Crude (PAC)—in saltwater under wave conditions using mesoscale spill tests. All oils exhibited rapid initial water uptake within 24 h and significant loss of light fractions due to evaporation. The resulting w/o emulsions exhibited increased density and viscosity over the 96-hour observation period. Their types and stabilities were influenced by water content and the composition of major subfractions remaining in the emulsions. These findings underscore the importance of understanding oil-specific properties and weathering processes to predict emulsion behavior and inform effective spill response strategies.