Technical Assessment of Using Dispersants On Marine Oil Spills in The U.S. Gulf of Mexico and California

Abstract

ABSTRACT This paper describes two comprehensive technical assessments of potential dispersant use in the Gulf of Mexico Region (GOMR) and Pacific Outer Continental Shelf Region (POCSR). The assessments considered both operational and environmental issues. Spill scenarios currently used for spill response planning or environmental impact assessments were analyzed. Dispersibility of oils and “time-windows” (TWs) for dispersant operations were assessed for GOMR- and POSCR-produced crude oils, as well as for oils imported into California. The TWs were estimated by oil fate modeling. It was found that most of the GOMR-produced oils for which data were available are light and dispersible when fresh. By contrast, only a few of the POCSR produced oils appear to be dispersible. The situation for oils imported into California is more favorable, as over 50% of crude oil volume imported annually is comprised of oils with adequate TWs. Logistic capacities of various dispersant application platforms were analyzed. Net environmental benefit (NEB) of dispersants was determined by analyzing a number of spill scenarios. Impact and NEB were estimated using models of oil fate, trajectory and environmental impact, combined with resource vulnerability databases. In the NEB-GOMR analysis, dispersants offered a clear net environmental benefit in every scenario. The NEB-POCSR analysis yielded similar conclusions, even though the study involved more complex scenarios.