Gulf well 'shouted' warnings for hours before BP rig explosion

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.

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.