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BP reports warning signs before gulf oil rig explosion

There were warning signs of a valve leak nearly five hours before the deadly gulf oil rig explosion, according to an internal BP investigation, which also found that a number of equipment and system failures may have caused the Deepwater Horizon disaster.

BP’s preliminary inquiry raises questions about the cementing of the deep-sea oil well and the blowout preventer that failed, members of the House subcommittee on oversight and investigations were told Tuesday.

The BP investigation identifies “new warning signs of problems” before the explosion, including “whether proper procedures were followed for critical activities throughout the day,” Rep. Henry A. Waxman (D-Beverly Hills) and Rep. Bart Stupak (D-Mich.), leaders of a congressional investigation into the disaster, said in a memo released late Tuesday.

As federal officials were briefed by BP, the company prepared for its much-anticipated “top kill” procedure, which could take place as soon as Wednesday. If it works — and BP executives have said there is no guarantee it will — the complicated underwater operation would finally stop the flow of crude, offering some relief to the embattled oil giant.

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If it doesn’t, BP has said it will try other fixes to cap the oil gusher. But another failure would add to growing political and public anger over the untamed spill, which has closed fisheries, fouled shorelines and tainted Gulf of Mexico waters.

The technique, never attempted at 5,000 feet, the depth of the BP leak, involves pumping heavy drilling mud into the well at a rate of 40 to 50 barrels per minute, followed by cement. The company had planned to turn off its live video feed of the leak during the procedure, but at the request of President Obama and the National Incident Center has decided to keep it on.

Against a background of mounting criticism of the federal response to the disaster, Obama changed his Memorial Day weekend plans to include a Friday trip to the gulf, where he will review cleanup efforts. And Capitol Hill lawmakers began considering tough new measures to ensure that industry pays the economic and environmental costs of oil spills.

According to the memo released after BP’s private congressional briefings, the company confirmed that the cement encasement that was supposed to seal the well failed, possibly because of contamination, releasing the geyser of oil.

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Contaminated cement leads to weak spots and, like a leak in a dam, can cause the entire structure to crumble.

BP’s investigators also said that once the cement failed, the crew received signs of the looming disaster but may have interpreted them incorrectly. They said that “fundamental mistakes” in reading tests of the integrity of the well may have been part of the reason the blowout reached the proportions it did.

Five hours before the explosion, for example, fluid was disappearing down the riser pipe connecting the rig to the well, suggesting a synthetic valve on top of the blowout preventer near the seafloor was leaking, according to the memo. Then a series of “pressure tests” on the system were conducted, and the results were peculiar. There was discussion and retesting.

But a final test was viewed as satisfactory, the memo said. So the crew proceeded — disastrously.

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The memo also revealed that, once the blowout occurred, the crew of the Deepwater Horizon had some time to fight back. Eighteen minutes before the explosion, they realized something was wrong and struggled unsuccessfully to contain the gas bomb that was hurtling toward them from the seafloor, the memo said. It remained unclear exactly what steps they took.

BP investigators also raised concerns about the blowout preventer, which failed to close and stop the surging oil once it started. Remote switches powered from the seafloor are designed to activate when the rig is ripped free from the well — say when a hurricane hits and hydraulic or electric connections with the rig are broken. But this disaster didn’t unfold like a hurricane, and none of these systems worked.

Transocean officials have suggested that part of the reason is that, despite the catastrophe on the water’s surface, the key connections to the rig may have freakishly remained intact, so the remote switches never received the signal.

“I understand people want a simple answer about why this happened and who is to blame,” BP Chief Executive Tony Hayward said Tuesday in a statement. “The honest truth is that this is a complex accident, caused by an unprecedented combination of failures. A number of companies are involved, including BP, and it is simply too early — and not up to us — to say who is at fault.”

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richard.simon@latimes.com

jill.leovy@latimes.com

Simon reported from Washington and Leovy reported from Los Angeles.

Times staff writer Bettina Boxall and Jim Tankersley of the Washington bureau contributed to this report.

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