NEW ORLEANS — Crews removed a cap from atop BP’s out-of-control well in the Gulf of Mexico on Saturday, beginning an ambitious engineering effort that could fully contain the huge oil leak but will also make matters worse, at least temporarily.
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.
But Mr. Wells said contingency plans were ready in case the installation failed. And even if a new cap is installed, the well will be open for at least several days, and more oil will pour into the gulf.
Mr. Wells expressed confidence that the new approach — the latest in a string of efforts, many of which have failed — would succeed. “In four to seven days, we’ll have that sealing cap in place,” he said.
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.
“Our intent is to have the ability to contain all the flow,” he said.
After a request from Adm. Thad W. Allen, the retired Coast Guard officer who is leading the federal response effort, to take advantage of an expected period of good weather and accelerate work to stem the leak, BP agreed to install the new cap as workers were bringing another collection system into operation.
“There’s going to be a lot of activity going on,” Mr. Wells said. “We’re ready to do it, and we’ve got a very good weather window.”
Work on the new collection system, which would funnel up to 20,000 barrels a day to another ship, the Helix Producer, had been delayed by high winds and rough seas. But Mr. Wells said Saturday that the system would probably start collecting oil on Sunday and reach full capacity a few days later.
That may help reduce the amount of oil that is now rushing unimpeded from the top of the well. Another system, which is diverting 8,000 to 9,000 barrels of oil a day to another vessel, should not be affected by the cap work.
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.
Mr. Wells said his team had a new looser-fitting cap, called a top hat, on standby should the installation fail.
To cope with the oil that leaks into the gulf during the cap-swapping procedure, BP has positioned more than 40 large or midsize skimmers near the well site and has 14 teams ready to conduct controlled burns.
“As we see oil coming to the surface, we’ll be ready to skim it,” Mr. Wells said.
Much like the failed blowout preventer, the new cap is outfitted with three valves that can be used to restrict the flow of the well. Mr. Wells said that as soon as the cap was installed, technicians would do just that, “shutting in” the well and taking pressure measurements.
Based on the results, he said, his team, with the help of government scientists and others, would decide how to proceed with other collection efforts.
The pressure readings would also be used to plan for the operation to eventually stop the leak and permanently seal the well by pumping heavy drilling mud into it, followed by cement, through a relief well.
Mr. Wells said that the first relief well was nearing its target point, but that the blown-out well would probably not be completely sealed until mid-August at the earliest.