BP Plc received approval to cement its damaged Macondo oil well in the Gulf of Mexico after reducing pressure with mud pumped from the top.
National Incident Commander Thad Allen authorized the cementing of the top of the well after BP’s successful completion of the so-called static kill, according to an e-mailed statement from the Joint Information Center. BP said it will begin pumping cement tomorrow.
BP’s well spewed an estimated 4.1 million barrels of oil into the Gulf after the Deepwater Horizon drilling rig, leased from Transocean Ltd., exploded April 20, killing 11 workers. For a permanent seal, BP still needs to complete a relief well and inject mud and cement from the bottom, which will probably take place “toward the end of August,” Allen has said.
“I made it clear that implementation of this procedure shall in no way delay the completion of the relief well,” Allen said today.
While the Macondo spill ranks as the world’s largest accidental offshore oil release, about 74 percent of the spewed oil has been eliminated or will soon be eaten by bacteria, the U.S. government said in a report today.
The remaining oil may be on the surface of the water, buried beneath sand and sediment, or was collected from the region’s beaches, according to the report by a team led by the Interior Department and National Oceanic and Atmospheric Administration.
An estimated 4.9 million barrels of oil leaked from BP’s Macondo well between April 20 and July 15, according to government scientists. BP was able to capture about 800,000 barrels before it entered the Gulf.
“The long battle to stop the leak and contain the oil is close to coming to an end,” President Barack Obama said in remarks today to the executive council of the AFL-CIO labor union.
Obama said the U.S. will hold the company accountable for paying for the damage caused by the leaking well, the biggest U.S. maritime oil spill.
“We want to get it sealed with cement, and we want to make sure it’s permanently sealed with cement,” Senior Vice President Kent Wells told reporters during a conference call.
A quarter of the oil from the spill evaporated or dissolved naturally into the water, according to the report by the Interior Department and the NOAA. BP captured 17 percent of the oil using equipment at the wellhead and skimming accounted for 3 percent.
“At least 50 percent of the oil that was released is now completely gone from the system,” Jane Lubchenco, administrator of NOAA, said during a press conference at the White House. “And most of the remainder is degrading rapidly or is being removed from the beaches.”
Chemicals were used to break up 8 percent of the oil and 16 percent was naturally dispersed, or broken down into small droplets that can be eaten by bacteria in the Gulf, according to the report.
“I find it very hard to believe, impossible actually, that they have three-quarters of the oil accounted for,” Samantha Joye, a professor of marine sciences at the University of Georgia in Athens, said in an e-mail.
Joye was among scientists who discovered plumes of oil under the Gulf’s surface and has been continuing to survey and analyze the results of water samples.
“When they say that there’s 25 percent of the oil remaining, that is almost five times the Exxon Valdez,” which spilled crude into Alaska’s Prince William Sound in 1989, said Ian MacDonald, a professor of oceanography at Florida State University in Tallahassee.
Though there may be no oil washing onto beaches, tar balls can be found six to 10 inches (15 to 25 centimeters) below the surface, he said.
“An enormous amount of the oil is now buried, and we know from previous spills that this buried material can persist for decades,” MacDonald said. “And that oil does have an effect on the behavior and health of the animals.”
BP rose 6 pence, or 1.4 percent, to 421.65 pence in London trading. The cost of insuring BP’s debt for a year with credit-default swaps dropped below five-year premiums for the first time in two months on speculation the bid to close the well will succeed.