Key device from Gulf oil spill raised, may solve mystery

ON THE GULF OF MEXICO - Investigators may now be able to answer the most elusive question since a rig explosion unleashed the massive Gulf of Mexico oil spill more than four months ago, as they get a close-up view of a key piece of equipment for the first time.

Why didn't it stop the oil? A crewman guided a crane yesterday to hoist the 50-foot, 300-ton blowout preventer from a mile beneath the sea to the surface. It took about 29 1/2 hours for the blowout preventer to reach the surface of the Gulf at 6:54 p.m. local time.

FBI agents were among the 137 people aboard the Helix Q4000 vessel, waiting to escort the device back to a NASA facility in Louisiana for analysis.

Crews had been delayed after icelike crystals - called hydrates - formed on the blowout preventer. The device couldn't be safely hoisted from the water until the hydrates melted because the hydrates are combustible, said Darin Hilton, the captain of the Helix Q4000.

Hydrates form when gases such as methane mix with water under high pressure and cold temperatures. The crystals caused BP PLC problems in May, when hydrates formed on a 100-ton, four-story dome the company tried to place over the leak to contain it.

The April 20 explosion aboard Deepwater Horizon killed 11 workers and led to 206 million gallons of oil spewing from BP's undersea well.

Investigators know the explosion was triggered by a bubble of methane gas that escaped from the well and shot up the drill column, expanding quickly as it burst through several seals and barriers before igniting.

But they don't know exactly how or why the gas escaped. And they don't know why the blowout preventer didn't seal the well pipe at the sea bottom after the eruption. While the device didn't close - or may have closed partially - investigative hearings have produced no clear picture of why it didn't plug the well.

Steve Newman, president of rig owner Transocean, told lawmakers after the disaster that there was no evidence the device failed and suggested debris might have been forced into it by the surging gas.

Recertifying the five-story device requires completely disassembling it out of the water and can take as long as three months to complete.