Impact of subsurface dispersant treatment on deepwater horizon (DWH) spill: May 10-12, 2010 treatment event

Document Type

Conference Proceeding

Date of Original Version



To experimentally assess the impact of subsurface dispersant treatment on surface oiling during the Deepwater Horizon spill, subsurface dispersant application was suspended from May 5 to 10, 2010, restarted late in the day on May 10, continued for a period of about 24 hrs, and then suspended again late in the day on May 11 through May 14 and restarted on May 15. Aerial imagery at the spill site during this period shows the presence, disappearance, and then reappearance of thick oil at the surface. An evaluation was performed to determine whether this temporal variation in thick oil could be explained by changes in surface entrainment due to breaking waves or surface or subsurface application of dispersants. Breaking wave induced entrainment was ruled out as the causative factor, since the wind speeds and wave heights measured at a nearby buoy did not indicate large changes correlated with the dramatic changes in observed surface oil volume. Surface dispersant treatment was also ruled out since the flight paths for aerial dispersant applications during this period were well to the east of the spill site. Application of the OILMAP DEEP blowout and SIMAP, spill transport and fate, models showed that the subsurface application of dispersants and its impact on droplet size distributions qualitatively explains the change in amount of oil at the sea surface during the May 10 to 12, 2010 treatment event and gives results that are fully consistent with the observations.

Publication Title

40th AMOP Technical Seminar on Environmental Contamination and Response

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