Gulf oil spill puzzle: A giant piece begins long rise to surface

The mystery of why the massive blowout preventer at the heart of the Deepwater Horizon accident failed and caused the enormous Gulf oil spill is a step closer to being solved.

Clearing the way for the drilling of a final relief well to permanently kill the Macondo well, BP and its now well-worn underwater remotely-operated vehicles (ROVs) disconnected the troubled piece of equipment at 1:20 Central time Friday in order to lift it to the surface of the Gulf of Mexico.

The pesky four-story steel structure, part of the BOP "riser package" that connected the rig to the wellhead, failed at the time of the Deepwater explosion, leading to one of the world's worst industrial oil spills. It later continued to thwart attempts by BP's deepwater submarines to manually activate its hydraulic on-board "shearing rams."

The blowout preventer is expected to become a key piece of evidence in several federal probes, including criminal investigations, to find out the cause of the spill.

Investigators are likely to find at least some remnants of the tons of debris -- including golf balls and shredded tires -- that BP attempted to jam into the BOP to stop the flow. The underwater gusher was finally stopped on July 15 after BP placed a large containment cap on top of the riser package to stabilize the well, and then jammed cement into the wellhead. The containment cap was successfully removed Thursday.

Retired Coast Guard Adm. Thad Allen, the federal incident commander, said it will take 24 to 36 hours for the BOP to make the long trip from the Gulf's darkest depths to the surface.

"We will continue to closely monitor progress as the BOP, which along with the latching device weighs approximately one million pounds, is lifted to the surface in the next 24-36 hours," Mr. Allen said in a statement.

BP shares rose on the news as did shares for Cameron International, the maker of the device.

According to Reuters, the BOP will be taken to a NASA facility in Michoud, Louisiana, where it will be examined by the US Coast Guard and the US Bureau of Ocean Energy Management, which are investigating the spill.

The blowout preventer "is one piece of evidence that has the potential to provide some answers," the team said on its website.

The spill caused an environmental nightmare in the Gulf, fairly ruined the summer tourist season, and reinvigorated a national debate about America's energy future. Federal regulators fanned out across the Gulf's shallow and deepwater drill rigs to double-test other BOPs as Washington imposed a drilling moratorium in the deep Gulf.

Placing a working BOP on the stymied well will clear the way for BP to move ahead with the final stage of killing the well: By mid-month, a two-pronged relief well effort will inject concrete into the wellpipe and surrounding casing at the bottom of the well, some 18,000 feet into the bedrock, officials say.

Over 200 million gallons of oil is estimated to have flowed into the Gulf after the Deepwater Horizon rig exploded on April 20, killing 11 workers and injuring 17 others.