(Corrects figure for total spill volume in seventh paragraph.)
June 11 (Bloomberg) -- BP Plc’s damaged well in the Gulf of Mexico has been leaking twice as much oil as previously estimated, a team of government scientists said in its latest report on the size of the worst spill in U.S. history.
The well is gushing 20,000 to 40,000 barrels of oil a day, according to an estimate released yesterday by the scientists, tasked by the government with calculating the flow. On May 27, the group pegged the rate at 12,000 to 19,000 barrels a day.
The latest figure is for the size of the leak prior to June 3, when BP sawed off a bent riser pipe, potentially increasing the amount of crude escaping by as much as 20 percent. The scientists don’t have a projection for the current flow, Marcia McNutt, director of the U.S. Geological Survey, said in a news conference yesterday.
“Our scientific analysis is still a work in progress, as you can tell from a range of estimates,” said McNutt, who is overseeing several independent flow-rate teams using different methods. Two offered revised flow models which were higher than those presented two weeks ago, she said. Another two are revising their data and will deliver their figures by the end of the month.
Preliminary figures from a team of Woods Hole Oceanographic Institution scientists suggest the well could be leaking as much as 50,000 barrels a day, McNutt said.
An accurate estimate of the volume is vital for those responding to the spill, according to U.S. Coast Guard Admiral Thad Allen. BP is capturing about half of the new estimated flow rate from the broken well, almost a mile down on the seabed of the Gulf of the Mexico, and siphoning it to ships on the surface.
Bigger Than Valdez
The “most credible estimate” for the size of the leak before the riser pipe was cut is 20,000 to 40,000 barrels a day, McNutt said. Her team hasn’t yet calculated the volume beyond June 3. Based on the midpoint of the latest approximation of 30,000 barrels, from April 22 when the Deepwater Horizon rig sank until June 3 the well gushed 1.26 million barrels of oil, or 52.9 million gallons.
The Exxon Valdez spilled an estimated 257,000 barrels in 1989. At a daily rate of 30,000 barrels, or 1.3 million gallons, the BP Macondo well disaster would generate that much every 8.5 days.
On June 3, BP sawed off the riser pipe that had been kinked near the seafloor, constricting the flow of oil from the leak. The clean cut allowed the company to secure a containment cap to the pipe, capturing some of the escaping oil and funneling it to ships at the surface.
Higher Flow Rate
BP suggested that cutting the pipe may have increased the flow rate by 20 percent. McNutt said her teams of scientists are still trying to calculate how much the volume might have changed since that operation.
BP collected 15,520 barrels of crude at the surface between noon on June 9 and noon on June 10, the last 24-hour period for which data is available. According to the midpoint of the latest estimates from the group of scientists, this would be about half of the oil being released each day.
The first ship positioned to capture the oil is able to collect 18,000 barrels a day. By next week, BP will raise that capacity by 55 percent to 28,000 barrels in total, Allen said yesterday in a press conference.
“We’re locked into a recovery mode that is way under capacity for what’s really coming out,” Ian MacDonald, an oceanographer at Florida State University in Tallahassee, said an interview after yesterday’s announcement.
MacDonald has estimated the well to be leaking 26,500 to 30,000 barrels a day, six times more than the figure that BP and the government used from April 28 to May 27.
50,000 Barrels a Day?
“A reasonable estimate is 22,000 barrels a day to 30,000 barrels a day,” said Tad Patzek, chair of petroleum and geosystems engineering at the University of Texas at Austin. “I don’t think 40,000 barrels a day. If BP starts recovering 28,000 barrels a day, then I will revise my estimate.”
A spill rate of 50,000 barrels a day is supported by an April 27 BP memo made public on May 27 by Congressman Edward Markey, a Massachusetts Democrat, Florida State University’s MacDonald said.
The memo included data on how BP had arrived at its high projection of 14,286 a day. BP assumed the oil was far thinner on the surface than it was, MacDonald said.
“BP fully supported this effort to establish the new estimates,” Max McGahan, a spokesman for the London-based company, said in a telephone interview. BP provided the scientific team with data and video, he said.
Each of the scientific methods being used has biases, which may shape the results they produce, McNutt said. After BP has captured all of the flow, scientists will be able to determine which methodologies were most accurate and what the biases were.
“We will be able to do a much better job next time,” she said.
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