OGJ Senior Staff Writer
HOUSTON, Aug. 27 -- BP PLC was unable to remove three pieces of pipe from the blown-out Macondo well in the Gulf of Mexico, and it now plans to retrieve the Transocean Ltd.’s Deepwater Horizon semisubmersible blowout preventer (BOP) with two pieces of pipe inside it.
Plans currently call for the drill pipe going down into the well to be left in place, National Incident Commander and retired Adm. Thad Allen said on Aug. 27. On Aug. 28-29, BP will make the necessary equipment preparations and move around vessels in advance of removing the capping stack and replacing the Deepwater Horizon BOP with a BOP from Transocean’s Development Driller II semi.
An Apr. 20 blowout of the Macondo well resulted in an explosion and fire on the Deepwater Horizon, killing 11 people. The Deepwater Horizon sank on Apr. 22. Macondo is on Mississippi Canyon Block 252 in 5,000 ft of water.
BP, operator of the Macondo well, had used a fishing operation to try and remove an 18-in. long pipe that was crosswise in the BOP. Crews previously cut off this pipe while installing oil containment equipment on top of the BOP. A second pipe, which is about 13 ft long, also is in the BOP.
“They are fragile, and they break apart when we try to pull them out,” Allen said of those two pipes. The third pipe, held suspended from the BOP, has been estimated at up to 3,500 ft long.
During an earlier “static kill” procedure, BP pumped heavy drilling mud and then cement into the casing from the top of the well following the July 15 installation of a capping stack (OGJ, Aug. 9, 2010, p. 27). No oil has been released into the gulf since then.
Transocean’s Discoverer Enterprise drillship is expected on Aug. 30 to remove the capping stack, which will be placed on the seabed in case it might be needed again. The Helix Q4000 multiservice vessel then will attempt to lift the Deepwater Horizon BOP, Allen said.
If necessary, crews are prepared to use what Allen calls “a gentle tug” involving 80,000 lb of force to free the BOP. Remotely operated vehicles then will be used to cut off the drill pipe below it.
If the gentle tug fails, then BP plans to open rams in the BOP’s lower marine riser package before it cuts off the pipe. Allen said BP is prepared to use tools to force open the rams.
Once the Deepwater Horizon BOP is removed, the DDII will install a different BOP on the wellhead in preparation for completion of a relief well, being drilled by the Development Driller III, to kill the Macondo well using mud and cement at the bottom of the well.
Assuming no tropical weather delays or problems with opening the rams, Allen estimates the DDIII could resume drilling the relief well on Sept. 7-8.
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