Washington - In a dramatic turn of events, the Obama administration has given BP the go-ahead to remove the containment cap atop the runaway Deepwater Horizon oil well and replace it with a tighter fitting one in an attempt to stop all the oil now flowing into the Gulf of Mexico, perhaps as soon as the middle of next week.

If successful, no oil would gush into the Gulf of Mexico for the first time since soon after the Deepwater Horizon exploded in flames on April 20.

Thad Allen, the Obama administration's point man on the oil spill, said Friday that the current containment cap will be removed on Saturday and that installation of the new one would begin three or four days later.

Once the new cap is in place, engineers will attempt to stop any oil from flowing out.

"Our first goal," Allen said of the new containment device, "would be to shut . . the well in. In other words, close all the means of oil to escape."

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It was unclear how, after more than 80 days, officials suddenly had a seeming solution to the gushing oil ready in a short period of time. While the new containment cap has been under construction for weeks, officials previously hadn't portrayed it as having such a potentially crucial role.

Allen didn't say how many days it would be before the cap would be in place, but a timeline that BP provided to Allen on Friday shows that if all things go as planned, BP would be able to close off the well five days after the old containment cap is removed.

If technicians encounter difficulties, that period might stretch to nine days, the timeline showed.

Bob Dudley, the BP executive in charge of the Gulf oil spill, said in a letter to Allen that included the timeline that switching the containment cap wouldn't begin until hoses are connected that would allow BP to add a third ship to collect oil from the blown-out well.

Allen, however, appeared satisfied that those preparations are well on the way to completion and that engineers "will likely be in a position to be able to start removing the current cap . . . tomorrow."

Just Wednesday, Allen had declined to lay odds on whether the Obama administration would approve the new containment cap, and Thursday he remained skeptical that BP would be able to close off the well until mid-August.

Allen laid the decision to the weather, saying forecasters are predicting a seven to 10-day window of calm weather.

"We think this weather window presents a significant opportunity for us to accelerate the process of capping — shutting down the well from the top and increasing the prospects for being able to kill the well from below through the relief wells," Allen said.

Allen also said other events had come together to assuage earlier concerns that capping the well at the top would cause damage to the well itself — a concern that caused officials to halt the so-called "top kill" effort in late May.

"If there is a problem and we have to release the pressure ... there'll be four different ways to take (crude out) . . . and produce it," lessening the pressure.

Allen described a multi-step process of robots unscrewing six bolts to remove the sheared-off riser pipe, strapping together two pipes that will remain so it's easier to fit the containment cap over them, then bolting the new contraption in place and sealing it with a valve.

There are, of course, no guarantees.

For one, while Allen talked of a seven to 10 days of calm weather, BP's timeline shows only an eight-day window — a window just barely long enough to accommodate the work if unbolting the well's riser pipe takes longer than the ideal.

BP also provided Allen with a list of backup plans should the new containment cap take longer to install than anticipated or not work as officials hope.

Among those, Dudley wrote, would be the stationing between the Deepwater Horizon site and the Gulf Coast of nearly 400 boats and more than 50 aircraft that would be expected to spot and scoop up the additional oil that would flow into the Gulf between the time the current containment cap is removed and the time the new one is installed.

The primary backup plan, however, is the completion of connections that would allow oil to flow from the Deepwater Horizon well's failed blowout preventer directly to the Helix Producer I drill ship. Those connections are in place, Allen said, and the Helix Producer may begin receiving oil as soon as Sunday.

Having the Helix Producer in place will help ease one immediate negative result of removing the current containment cap — once it's gone, the 15,000 or so barrels of oil a day that had been collected through it by the Discoverer Enterprise drill ship will spew directly into the Gulf until the new cap is in place.

Allen said, however, that by Tuesday the Helix Producer will be taking on at least as much oil as the Discoverer Enterprise was.

"We're hoping to mitigate the gap without having the capping device on by bringing the Helix Producer on board," Allen said.

Allen also said the new capping device will help officials determine whether the Deepwater Horizon's wellbore was damaged by the April 20 explosion and fire that raged for more than 36 hours after. The condition of the wellbore has been a concern for weeks. A damaged well bore would complicate plans to kill the well permanently by pumping heavy drilling mud into it through a relief well.

Allen said that with the cap in place and closed, technicians will be able to measure the pressure inside. A pressure of 9,000 pounds per square inch, engineers believe, will be a sign that no oil is leaking out of the wellbore. A lower pressure would indicate that oil and natural gas are leaking out of the wellbore into the surrounding seabed.

The decision to move ahead with capping the well also complicates the task of determining how much oil is leaking from the well. Previously, Allen had said that government scientists would have a better chance of refining estimates of the leak once three ships were in place with a capacity to collect 53,000 barrels of oil a day. Currently, government scientists have said the well is gushing between 35,000 and 60,000 barrels per day.

With the new cap sealing the well, however, Allen said government scientists would have to estimate the well's flow rate solely by knowing precisely the pressure within the cap.

In addition, Dudley also outlined a schedule for permanently sealing the well with heavy drilling mud and cement through the relief well by Aug. 13, a date more in line with what Allen and others have long said was the most likely timeline.

That schedule forecasts that drillers of the relief well will be within 100 vertical feet of where they hope to intercept the runaway well by Monday and that by a week later, they should be ready to drill into the well bore and begin pouring heavy drilling mud into the well's "annulus," the space between the wall of the well and the drilling pipe inside.

That process will take 10 days, BP estimated, after which drillers will enter the pipe itself and pump in drilling mud and cement, a procedure that will take 14 days.

On The Web

Letter from BP's Bob Dudley outlining plans to cap gushing well.

Transcript of Thad Allen's Friday briefing. 

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