BP PLC plans to move ahead with replacing the blowout preventer that sits atop the well that unleashed the Deepwater Horizon oil spill, despite failing in attempts to remove pieces of drill pipe stuck inside the device, the federal oil-spill response chief said Friday.
Preparations for the blow-out preventer's removal will begin Friday and last through the weekend, and the new blow-out preventer should be in place Tuesday or Wednesday, retired U.S. Coast Guard admiral Thad Allen told reporters in a conference call.
If the operation is successful, responders could begin the final step to kill the well, which involves pumping mud and cement down the area between the well and the rock formation that surrounds it, on Sept. 7, he said. That operation could take as many as 96 hours, according to Mr. Allen.
The plan coincides with previous projections that the well would be officially dead by the week after U.S. Labor Day, Sept. 6. Mr. Allen said, however, that the timeline is dependent on current conditions, and that changes in weather or developments in the field could push it out. The timelines "are as good as the next observation we find out," he said.
U.S. officials were concerned that the injection of liquid into the gap between the well and the rock—known as the annulus—could compromise a cement plug that BP cast at the top of the well in early August, letting some oil escape into the ocean. Hence the need for a new, stronger blow-out preventer, a valve designed to prevent such explosions.
Responders initially attempted to fish out broken pieces of drillpipe stuck inside the blow-out preventer currently in place, to make its removal easier. But their efforts failed as the fragile pieces of pipe broke apart when BP tried to pull them out, Mr. Allen said.
Instead, BP will attempt to give the blow-out preventer a "gentle tug" that is expected to lift it, and cut the drill pipe underneath the valve with submarine robots, Mr. Allen said. If the device doesn't pull free, BP can apply as much as 80,000 pounds of pressure to remove it. If that doesn't work, the company will manually open rams at the bottom of the valve and cut the pipe at the well head, Mr. Allen said.
Before lifting the blow-out preventer, the capping stack that shut off the flow of oil in mid-July will be removed and temporarily stored at the bottom of the ocean, Mr. Allen said.
