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Oil spill dumped 4.9 million barrels into Gulf of Mexico, latest measure shows

By Joel Achenbach and David A. Fahrenthold
Washington Post Staff Writer
Tuesday, August 3, 2010; A01

The blown-out well in the Gulf of Mexico gushed 12 times faster than the government and BP estimated in the early weeks of the crisis and has spilled a whopping 4.9 million barrels, or 205.8 million gallons, according to a more detailed analysis announced late Monday.

BP's Macondo well spewed 62,000 barrels of oil a day initially, and as the reservoir gradually depleted itself, the flow eased to 53,000 barrels a day until the well was finally capped and sealed July 15, according to scientists in the Flow Rate Technical Group, supervised by the U.S. Geological Survey and the U.S. Department of Energy.

The new numbers once again have nudged upward the statistical scale of the disaster. 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.

The new flow rate figures came as engineers made final preparations for a "static kill" operation that might plug the well permanently even before a relief well intercepts Macondo at its base. BP announced late Monday that the procedure would be delayed, probably until Tuesday, because of a leak in the hydraulic control system on the well's new cap.

(Photos: Oil spills through history)

Macondo's flow rate has been a major source of controversy since the April 20 explosion on the Deepwater Horizon. Early in the crisis, the Coast Guard and BP pegged the flow at 5,000 barrels a day, sticking with that figure even as outside scientists declared that it low-balled the actual rate. The flow rate team, assembled in May, tried to come up with a more solid figure. Scientists examining the surface slick as well as video taken by submersibles soon upped the estimate; by early June, the government declared the flow to be 35,000 to 60,000 barrels a day.

Even the high end of that estimate did not quite do justice to Macondo when it was at full throttle in the early weeks of the crisis. The new figures reflect more data, including high-definition video, sonar measurements of the oil-gas ratio, and pressure readings in the new capping stack before, and then after, the sealing of the well July 15.

"We may never know the exact answer. But as we get more data, you're able to shrink the uncertainty," said Bill Lehr, senior scientist for the National Oceanic and Atmospheric Administration and a leader of one of the teams.

The new figures indicate that the roughly 800,000 barrels of oil that BP managed to capture with its various containment strategies -- a riser insertion tool, a "top hat," and flaring from a surface rig -- represented only about one-sixth of the crude that surged into the gulf over the course of nearly three months. In all, about 1.2 million barrels of oil have been accounted for, either burned, captured or skimmed off the ocean's surface. That's about a quarter of the new estimate for the total spill.

Where the other three-quarters has gone is unclear. Some has evaporated; some has been consumed by microbes; but scientists remain troubled by the possibility that large amounts of oil remain underwater in cloudlike plumes.

"This further confirms that a lot of the oil is still at sea. And we just don't know the implications of it," said Ron Kendall, director of the Institute of Environmental and Human Health at Texas Tech University. Kendall will testify before Congress on Wednesday about his fears that dispersant chemicals have helped much of this oil sink into deep-sea habitats.

For government lawyers preparing a case against BP, this number could help calculate the maximum civil penalty BP might face for the spill. If BP is not found to have acted with negligence, the penalty would be $1,100 per barrel. About 4.1 million barrels escaped into the gulf, according to the new estimate, so that fine would come to $4.5 billion. If BP is found to have acted with "gross negligence" in the lead-up to the spill, the maximum penalty would be $4,300 a barrel, which would work out to $17.6 billion.

"You've got to go in with a number," said David Uhlmann, a law professor at the University of Michigan and the former chief of the Justic Department's Environmental Crimes Section. "And I think these numbers strengthen the government's hand," compared with previous estimates that produced only a range.

In all, the 4.1 million barrels estimated to have polluted the gulf would be enough to fill the Pentagon to a depth of 18 feet or to fill 260 Olympic swimming pools. The entire Gulf of Mexico, by comparison, would fill 880 million Pentagons, or 973 billion Olympic pools.

John Amos at SkyTruth, an organization that uses satellite imagery to study environmental problems, said that this new figure showed how far off BP and the Coast Guard were in the crucial days at the beginning of the spill.

"When the next spill happens, being in the right order of magnitude with the spill estimate is going to be important," he said.

The well remains pressurized and dangerous, but BP and government officials hope that will change with the static kill attempt. The goal is to inject mud into the well and drive the oil back to the source rock.

First comes what BP calls an injectivity test. Mud will be pumped into the well from a surface ship at a gentle rate of one barrel a minute, then two barrels a minute, then three, as engineers monitor pressures and look for signs that the rogue oil is being forced back into the source rock 2 1/2 miles below the seafloor.

"We want to confirm that we can inject the oil that's in the well bore back into the reservoir," BP Senior Vice President Kent Wells told reporters Monday.

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