Probabilistic oil-spill occurrence estimates are used by the United States Department of the Interior (USDOI), Bureau of Ocean Energy Management (BOEM) to support the development of National Environmental Policy Act assessments for hypothetical exploration and development scenarios in the U.S. Chukchi and Beaufort seas. Due to the limited offshore oil development in this region, it was not feasible to base these oil-spill occurrence estimates on empirical data from that region alone. Rather, statistically significant non-Arctic empirical data on oil spills of 50 bbl or more from the U.S. Outer Continental Shelf (OCS) including the Gulf of Mexico (GOM) and Pacific (PAC) OCS, together with their variance, are used as a starting point, to be adjusted using fault and event tree methodologies to emulate Arctic conditions. This paper, however, addresses the base statistical data for U.S. GOM and PAC OCS oil spills as well as world wide data on well control incidents including oil and gas blowouts. The first database contains information on crude, condensate and refined petroleum oil spills reported to the Bureau of Safety and Environmental Enforcement (BSEE), primarily from the GOM. As reports on this database up to 2008 were published earlier by the authors, this paper focuses on more recent updates to 2012, giving oil spill statistics for subsea oil pipelines, platforms, and wells in the U.S. OCS. A preliminary assessment of loss of well control incidents is also reported based on both BSEE and SINTEF data. The paper discusses the results of the U.S. statistical updates and the world wide well control preliminary statistics developed under current contracts of the first author’s company with BOEM. Conclusions summarizing the status and applicability of the statistics presented are given, and avenues for future work are identified.

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