Crews Set to Begin Swap of Oil Containment Caps

Workers at the BP oil spill site in the Gulf of Mexico will begin a complicated operation this weekend that they hope will let them contain most of the oil gushing from the seafloor.

But for possibly a couple of days, oil will flow unimpeded into the sea.

National Incident Commander Thad Allen said Friday that undersea robots will begin removing a cap mounted over the jagged remnants of the well head Saturday.

Special Section: Disaster in the Gulf

They plan to put a new containment cap that will form a better seal. Then, up to four ships will begin collecting the oil and gas.

The time from beginning the removal of the old cap to attaching the new cap will take about three to four days.

Allen on Thursday sent BP a letter demanding details about contingency plans in the event they have to proceed with the simultaneous maneuver or if the sealing cap installation fails, including due to severe weather. The oil company has 24 hours to respond.

Thad Allen's July 8 Letter to BP

There are currently two vessels siphoning oil from the gushing undersea well: the Discovery Enterprise, which captures an estimated 15,000 barrels of oil a day, and the Q-4000, which captures about 10,000 barrels a day.

Crews are working to connect a third ship, the Helix Producer, which would help another 25,000 barrels daily.

If everything works as planned, officials hope the total capture capacity could increase to 80,000 barrels daily with the sealing cap, reports CBS News White House correspondent Mark Knoller.

One official said it would bring the operation "closer to full containment."