Dispersant kept Deepwater Horizon volatiles from surfacing

Among the many responses to the 2010 Deepwater Horizon oil spill disaster, from skimming oil from the Gulf of Mexico’s surface to capping the Macondo well, perhaps the most controversial was injecting dispersant at the wellhead. Dispersant was sprayed on previous surface spills but never injected below the water. In the Deepwater Horizon incident, responders used subsea injection to try to dissolve as much of the released oil and gas in the water as possible to keep the hydrocarbons away from cleanup workers’ lungs and coastal ecosystems. A modeling study now finds that subsea dispersant injection increased hydrocarbon dissolution by 25%, ultimately preventing 27% of petroleum fluids released on a representative day from rising to the surface and reducing workers’ exposure to volatile organic carbon species (Proc. Natl. Acad. Sci. USA 2017, DOI: 10.1073/pnas.1612518114). The research team, led by Scott A. Socolofsky of Texas A&M University and J. Samuel Arey of the Eawag research institute, determined that injected dispersant increased hydrocarbon dissolution by reducing the size of hydrocarbon droplets and bubbles, increasing their surface area relative to their volume and slowing their ascent.