Posted on Wed, Sep. 01, 2010
last updated: September 02, 2010 07:55:12 AM
WASHINGTON — BP will begin removing the failed Deepwater Horizon blowout preventer on Thursday, if seas calm as forecast in the Gulf of Mexico, the Obama administration's pointman on the oil spill told reporters Wednesday.
Retired Coast Guard Adm. Thad Allen said forecasters expected waves to be less than four feet by midday, allowing ships to lift first a containment cap that sealed the well July 15, then the blowout preventer, which has been subpoeaned by federal investigators probing why the Deepwater Horizon well exploded April 20, killing 11 workers and setting off a months-long economic and ecological disaster.
Allen said the blowout preventer would be hauled aboard the Q4000 drilling rig, then transferred to barges to be taken to shore. Federal criminal evidence experts will oversee the device's recovery, Allen said. Robot vehicles equipped with video cameras will monitor the operation from the beginning.
"There'll be a chain of custody to make sure that we know exactly the condition and that there is continuous monitoring . . . including ROVs when we start to actually move it," Allen said.
He said the Justice Department had provided detailed guidelines for how the equipment is to be preserved.
Operations have been on hold at the well site 48 miles off the Lousiana coast since Monday, when engineers originally had hoped to begin moving the blowout preventer, because waves there were six to eight feet tall. Seas that rough risked putting too much pressure on the equipment needed to lift the blowout preventer, which weighs nearly half a million pounds, Allen said. The pipes that would tie it to the Q4000 add another 500,000 pounds.
"You can imagine the Q4000 riding up and down on the waves," Allen said. "When they ride up it exerts more dynamic loading on that pipe system. So were concerned about the weight and the ability of the pipe system to handle that."
Calm weather is expected to last till Sunday — enough time, Allen said, to remove the blowout preventer and place a new one over the well.
After the new blowout preventer is in place and has been tested, crews aboard the Development Driller III drilling rig will renew work on a relief well that Allen has said is the only way to ensure that the Deepwater Horizon well is truly dead. That work will begin sometime after the Labor Day weekend, Allen said. Technicians anticipate that it will take four days to drill the 50 feet needed to reach the depth where engineers would like to intercept the Deepwater Horizon well. Pumping heavy mud and then cement into the well after that could take anywhere from a few days to two weeks, BP officials and Allen have said previously.
No oil has leaked from the Deepwater Horizon well into the Gulf of Mexico since July 15, when the containment cap was placed atop the blowout preventer, and the well has been dead since Aug. 3, when BP pumped more than a million pounds of heavy drilling mud into it, forcing the oil back into rock formations 13,000 feet below the seafloor. BP then poured cement into the well, sealing it, on Aug. 5 and a variety of tests since have confirmed that no oil is flowing out of the rock formations into the well.
Allen and government scientists have insisted, however, that the relief well be completed. Allen said last week that only the relief well will confirm for government scientists that the connection between the reservoir and the well's annulus — the area between the rock walls of the wellbore and the outside of drilling pipe — is blocked permanently.