Based on new pressure readings, data, and analysis, the U.S. scientific teams charged by National Incident Commander Thad Allen with determining the flow of oil from BP’s leaking well have refined their estimates of the oil flow prior to the well being capped on July 15. The new estimates, which draw heavily on recent oil reservoir modeling and on pressure readings of a closed system, are the most accurate to date and have an uncertainty of plus or minus approximately 10 percent.

Overall, the scientific teams estimate that approximately 4.9 million barrels of oil have been released from the well, making it the largest accidental spill of all time. Not all of this oil and gas flowed into the ocean; containment activities conducted by BP under U.S. direction captured approximately 800,000 barrels of oil prior to the capping of the well.

The scientific teams estimate that 53,000 barrels of oil per day were leaking from BP’s well immediately preceding its closure via the capping stack.

Recent measurements and modeling also show that, as a result of depletion of the hydrocarbon reservoir, the daily flow rate decreased over the 87 days prior to the well’s closure. Based on these measurements and modeling, the scientific teams estimate that, at the beginning of the spill, 62,000 barrels of oil per day were leaking from the well.