Sunday, July 11, 2010

Switching Caps on the Leaking Oil Well

The Discoverer Enterprise and other ships flare off oil from the well / US Coast Guard Photo

With permission from the federal government, BP is attempting a risky operation to replace its first cap on the riser pipe with one that can capture more of the leaking oil.
Live video showed the cap, which had been diverting 15,000 barrels of oil a day to a ship on the surface, being lifted off the well at the seabed. As the cap was moved away, oil gushed anew from the well.

Kent Wells, a BP senior vice president in charge of the effort, said a tighter-sealing cap would be installed by the middle of this week. “At this point, we’re on plan,” he said, speaking at a briefing in Houston....

The old cap formed a loose seal, and oil and gas constantly escaped from it. The new one, two heavy-duty pieces of equipment that together are 30 feet high and weigh more than 100 tons, should eventually enable BP to collect all the oil from the well, estimated at up to 60,000 barrels a day. It will be used to divert more oil to collection ships that will be brought in over the next two to three weeks, Mr. Wells said....

The installation of the new cap is complex and, as with previous undersea efforts to contain or stop the gusher, is being done by remotely operated robots in extreme conditions of temperature and pressure 5,000 feet below the surface of the gulf.

Mr. Wells said that after the old cap was lifted off, the robots began removing six bolts that attached a remaining stub of riser pipe to a flange on the failed blowout preventer, the stack of safety equipment atop the well at the seabed. The bolt removal was expected to take the better part of a day, he said.

When the riser stub is removed, two pieces of drill pipe — presumably one that was in the riser when the blowout occurred on April 20, and one that was driven or fell into it in the disaster — will be sticking out of the flange. These will have to be bundled with a strap, Mr. Wells said, to make it easier to put the new cap on.
While this is going on, the oil will be leaking at the pace it was before. BP is planning to position more skimmers above the leaking wellhead and conduct more controlled burns in the interim. However, we know that these do not dissipate all of the oil. The upside, though, is that the operation could shut off most or all of the leaking oil once the new cap is in place. If you would like a more technical explanation of the replacement process (with pictures), see The Oil Drum's post on the new cap. I hope that this operation succeeds quickly.

The best hope for stopping the flow of oil continues to be a relief well. Right now the target date for its completion is still mid-August.