Oil droplet from blowouts: Role of gas and dispersant

Oil and gas often emanate jointly during a subsea oil blowout. Based on the proportions of the two phases, the hydraulic regime within the pipe could be bubbly, churn, slug, annular, and dispersed. We hypothesized herein that the regime impacts the oil droplet size distribution (DSD) in the blowout in the absence and presence of chemical dispersant (essentially surfactant). In this paper, we conducted oil and air jet releases in a 0.6 m diameter, and 2.6 m vertical water tank. The results showed that the churn flow caused a decrease of oil droplet sizes under the condition of same effective momentum, demonstrating that extra turbulence was introduced in the flow compared to bubbly flow. The application of dispersant significantly decreased the droplet sizes for both oil-only flow and oil-air jets. The phenomena of compound droplets were also identified for both oil only jets and oil-air jets. Generally, this work can contribute both experimental benchmarks for model validation and practical guidance for optimizing response decisions during deepwater oil spill events.