BP could start cap switch on Saturday: Coast Guard

Sheens of oil from the Deepwater Horizon oil spill are visible near barges set up as a barrier against oil in a major waterway leading to Lake Pontchartrain, near Slidell, Louisiana July 8, 2010.

HOUSTON (Reuters) - BP Plc is preparing for a key procedure to replace the containment cap over its blown-out Macondo well, which could temporarily cause more oil to gush into the Gulf of Mexico, the top official overseeing the spill response said on Friday.

With an eye toward capitalizing on a 7-10 day stretch of predicted storm-free weather, retired Coast Guard Admiral Thad Allen wants BP to switch to a larger containment system that can capture up to 80,000 barrels per day, versus about 28,000 bpd currently.

BP could remove the cap from the well on Saturday and install the new cap by late Sunday or early Monday, Allen said.

BP was hooking up a third production vessel on Friday that could begin siphoning crude by Sunday, Allen said.

The vessel is intended to increase oil-capture capacity to 53,000 barrels a day. The cap system must shut down while the caps are switched, so the third vessel will "probably be able" to fill the gap in the interim, Allen said.

In other developments:

* The first of two relief wells was within six feet of the side and 212 feet from the bottom of the blown-out well on Friday.

* Once the new cap is installed, BP and U.S. government scientists should get solid data on how much oil is leaking, Allen said. The scientists' latest estimate is up to 60,000 barrels a day.

*BP said its current oil-capture systems at the leak collected or burned off 24,395 barrels of oil on Thursday.

(Additional reporting by Jeff Mason in New Orleans; editing by Vicki Allen)