WASHINGTON — The crew of the Deepwater Horizon had a number of warning signs extending over five hours that conditions were worsening deep underwater before the oilrig exploded in the Gulf on April 20, BP's own investigators told a House inquiry into the cause of the deadly accident.
Details of BP's internal investigation provide fresh information about the extent of failures on the ill-fated rig, but the oil company's inquiry skirts the central question: why were those warnings ignored?
The apparent complacency of the BP crew comes as the Obama administration wrestles with the scope of possible new regulations on deepwater drilling and as a White House ordered inquiry is poised to release its findings on the explosion and spill.
Meanwhile, BP is set to attempt Wednesday to stanch the leak a mile below the surface. Oil company officials say the odds of success are 60 to 70 percent.
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In its report to Congress, BP said crews noticed unusual pressure and fluid readings that should have alerted them not to remove heavy drilling lubricants known as "mud" from the well — a move that apparently allowed a sudden upwelling of gas that led to the explosion and sinking of the rig about 50 miles from the Louisiana shoreline.
The first warning came five hours before the explosion, congressional investigators with the oversight subcommittee of the House Energy and Commerce Committee said in a memo released Tuesday evening. There was evidence that throughout the day crews failed to follow proper procedures for critical activities, and had readings 51 minutes before the explosion that showed more fluid was being pumped out of the well than was being pumped in.
"It appears that BP and Transocean had multiple warnings before the rig exploded," said Rep. Henry Waxman, D-Calif, chairman of the House Energy and Commerce Committee. "We need to know why they didn't shut down the well while there was still time."
Even though pressure readings indicated "a very large abnormality," BP continued to replace drilling mud with seawater. That move, BP's team told the subcommittee's investigators, may have been a "fundamental mistake."
The memo also suggests that some cement work failed, including crucial components designed to hold back oil and gas and prevent an explosion.
Because the drilling mud was being offloaded to a separate vessel instead of the rig's own tanks, the Deepwater Horizon's crews may have had a difficult time monitoring overall fluid levels and pressure.
BP's investigative team doesn't appear to have discussed with the committee exactly who was responsible for making the decision that could have led to the explosion. It also fails to explain why the crew moved forward with replacing the drilling mud, although as little as 18 minutes before the explosion, data suggests the crew attempted some sort of mechanical interventions to control the pressure, but it continued to increase and "the explosion took place."
Regardless, there are clear indicators they should have stopped, said Bob Cavnar, a Houston engineer who's been involved in oil and gas exploration and production and has been following the investigation on his blog, the Daily Hurricane.
"These wells talk to you all the time, and if you're not paying attention to the language they speak, sometimes they bite you," Cavnar said. "What killed these guys was complacency. It was shouting at them, but they ignored it."
And the systemic failure of the rig's blowout preventers raise questions about the overall safety of the devices on other Gulf of Mexico rigs.
The ones on the BP rig had failures on nearly every front, the company's team told the committee. Its emergency disconnect system failed, the so-called "deadman switch" failed, the shear rams that should have cut through the drill pipe failed, and remote vehicles couldn't fix them.
Their investigation "raised concerns about the maintenance history, modification, inspection and testing" of the blowout preventer, the committee's memo said.
BP briefed the administration Monday on its investigation; the White House had no comment on the memo from Waxman's committee.
The company's investigators spoke Tuesday morning with investigators with the House Commerce and Energy Committee, and briefed staffers with the House Natural Resources Committee Tuesday afternoon. They are set also to brief the Senate Energy and Natural Resources Committee staff on Wednesday.
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