Technology assessment of the use of dispersants on spills from drilling and production facilities in the Gulf of Mexico outer continental shelf

The operational and environmental issues associated with dispersant use to clean up oil spills in the Gulf of Mexico (GOM) was assessed. The assessment included an examination of the dispersibility of oils plus the capabilities and limitations of spray platforms as well as the net environmental benefit of dispersing spills. Spill scenarios involving typical spill types, oil types, sizes, locations and environment were also analyzed. Gulf oils are typically light and apparently dispersible when they are fresh. The impact of weathering on dispersibility of GOM oils was assessed by analyzing oil spill scenarios. The time window (TW) for dispersion was estimated by oil fate modeling. Only 28 per cent of the oils produced in the GOM have been sufficiently characterized to allow for modeling. The majority of oils produced in the GOM have TW of a few days or longer, and are therefore amenable to chemical dispersion. The maximum theoretical dispersant delivery capacities of a range of spraying platforms were estimated using spreadsheet models. The environmental benefits of using dispersants were greatest in situations involving spills of manageable size, with persistent but dispersible oils and with a TW of more than 24 hours. This is because the oils would otherwise persist long enough to reach the shorelines where they would pose a threat. This analysis also suggested that the net environmental benefit is greater in a blowout spill than in a comparable batch spill. 23 refs., 5 tabs., 2 figs