There was more testimony this week into the catastrophic chain of events set off when the Deepwater Horizon oil rig exploded nearly a year ago, killing 11 rig workers and unleashing the largest offshore oil spill in U.S. history.
A federal inquiry is focusing on the failure of the rig's blowout preventer, safety equipment designed to stanch out-of-control oil wells.
Federal officials hired a team of forensic experts to examine the Deepwater Horizon's blowout preventer, obviously not the fail-safe device the oil and gas industry counted on to prevent a disaster like the Gulf of Mexico oil spill.
The four-story stack of valves, seals and hydraulic rams was salvaged from the ocean floor and examined by the Norwegian risk-management firm Det Norske Veritas.
Off-Center Drill Pipe
For the first time Monday, the team's leader, DNV Vice President Neil Thompson, a material sciences engineer, testified before a joint panel of the Coast Guard and the Bureau of Ocean Energy Management, Regulation and Enforcement meeting outside New Orleans.
When something goes wrong with a well, the blowout preventer's shears are supposed to clamp down, cut and seal the drill pipe, preventing the oil from escaping. But in this case, Thompson said, that didn't work because after the force of the explosion, the drill pipe wasn't aligned just right.
"The primary cause was that the drill pipe was off-center in the well bore," he said.
Using computer-generated models, Thompson showed his team's theory about what happened when the shear rams tried to cut the flow.
"You can see the pipe begins to fold in, but there's a portion of pipe that is caught between the two ram block faces," he said, "and they can't fully close."
But lawyers for the companies responsible for the rig and blowout preventer questioned the findings as a novel and unprecedented theory. They argued that investigators failed to test all of the possible explanations for what might have caused the device to fail.
All of the interested parties in the Deepwater Horizon explosion get a chance to question witnesses.
"Dr. Thompson, do you have any operational experience working on a drilling rig?" attorney David Jones, who represents Cameron International, the company that made the blowout preventer, asked Thompson.
"I do not," he replied.
"Before your involvement in this investigation, had you laid eyes on a blowout preventer?" Jones continued.
"I had not," Thompson said.
The forensic testing of the blowout preventer has been fraught with delay and controversy, as attorneys weighed in on how to make sure all of the evidence collected from the Gulf floor is preserved for litigation purposes.
Safety experts from the companies are expected to testify later this week, with the exception of rig operator Transocean. The company's officials have refused to appear while at the same time doling out bonuses for "the best year in safety performance in our company's history."
"Some companies just don't get it," William Reilly, co-chairman of President Obama's oil spill commission, said in a teleconference Monday. "I think Transocean doesn't get it."
Unlike the board meeting in Louisiana this week, the presidential panel has completed its investigation, and blames the oil spill on a series of time- and money-saving decisions and management missteps by Transocean, BP and Halliburton.
Transocean says it regrets "insensitive" wording in its securities filing. Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.
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