Oil Budget Calculator, which concludes that of the estimated 4.9 million barrels released after the Deepwater Horizon off-shore rig exploded and sank last April, roughly 77% either was directly recovered, burned off, skimmed, dispersed or evaporated or dissolved. The earlier report release in August by the government put the percentage at about 74%.
The conclusion are based on data such as the amount of oil captured at the wellhead, combined with model-projected estimates based on historical oil spill data for similar types of oil, as well as the expertise and observations of oil- and oil spill-response scientists from government agencies, academia and the energy industry.
According to the report, chemical dispersants did a better job of breaking up oil spilled from BP PLC's blown-out Gulf of Mexico well than previously estimated. The most significant change from the August report is that government scientists have doubled the amount of oil classified as "chemically dispersed"— from 8% in August to an estimated 16% now. (NOAA, WSJ, 11/24/2010)