New Estimate Puts Gulf Oil Leak at 205 Million Gallons

BY Maureen Hoch  August 2, 2010 at 10:07 PM EDT

After weeks of calculating and revising, the group of scientists appointed by the government to estimate the size of the Gulf of Mexico oil leak have released new figures that, if correct, will make the leak the world’s largest accidental spill.

The move comes as engineers prepare to start a “static kill” procedure that will help permanently fix the underwater gusher.

In a statement, the team estimated that immediately before the well was capped on July 15, 53,000 barrels (2.2 million gallons) of oil per day were leaking from BP’s broken wellhead. But in the initial period after the spill began, 62,000 barrels of oil (2.6 million gallons) per day were leaking from the well. That’s 4.9 million barrels total or 205.8 million gallons. From the release:

> Today’s 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.

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.

Overall, the scientific teams estimate that approximately 4.9 million barrels of oil have been released from the well. 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

“We’ve never had a spill of this magnitude in the deep ocean,” Ian MacDonald, a professor of oceanography at Florida State University, told the New York Times.

The numbers confirm the historial nature of the spill. As the Washington Post’s Joel Achenbach and David Fahrenthold explain:

If correct — the government allows for a margin of error of 10 percent — the flow rate would make this spill significantly larger than the Ixtoc I blowout of 1979, which polluted the southern Gulf of Mexico with 138 million gallons over the course of 10 months. That had been the largest unintentional oil spill in history, surpassed only by the intentional spills in 1991 during the Persian Gulf War.

We’ll have more analysis of the figures and updates to our Gulf Leak Ticker on Tuesday. Stay tuned.