Risk of large oil spills: a statistical analysis in the aftermath of Deepwater Horizon.

The oil spill in the Gulf of Mexico that followed the explosion of the exploration platform Deepwater Horizon on 20 April 2010 was the largest accidental oil spill so far. In this paper we evaluate the risk of such very severe oil spills based on global historical data from our Energy-Related Severe Accident Database (ENSAD) and investigate if an accident of this size could have been "expected". We also compare the risk of oil spills from such accidents in exploration and production to accidental spills from other activities in the oil chain (tanker ship transport, pipelines, storage/refinery) and analyze the two components of risk, frequency and severity (quantity of oil spilled) separately.