Gulf Oil Spill
In this image taken from video provided by BP PLC at 18:01 CDT, oil flows from the broken well, center, as a new containment cap, left, hovers near t...
In this image taken from video provided by BP PLC at 18:01 CDT, oil flows from the broken well, center, as a new containment cap, left, hovers near the site of the Deepwater Horizon oil spill in the Gulf of Mexico, Monday, July 12, 2010. Deep-sea robots swarmed around BP's ruptured oil well Monday in a delicately choreographed effort to attach a tighter-fitting cap that could finally stop crude from gushing into the Gulf of Mexico nearly three months into the crisis. (AP Photo/BP PLC) NO SALES
GULF OIL SPILL
Map shows the forecast location of oil
Map shows the forecast location of oil
Gulf Oil Spill
In a photo made from video released by BP PLC, oil emerges from a cap placed on the broken wellhead at the former site of the Deepwater Horizon oil r...
In a photo made from video released by BP PLC, oil emerges from a cap placed on the broken wellhead at the former site of the Deepwater Horizon oil rig Tuesday morning July13, 2010 at 11:48 a.m. EDT in the Gulf of Mexico. After securing a new, tight-fitting cap on top of the leaking well, BP prepared Tuesday to begin tests to see if it will hold and stop fresh oil from polluting the waters for the first time in nearly three months. (AP Photo/BP PLC) NO SALES
Gulf Oil Spill
National Incident Commander Ret. Coast Guard Adm. Thad Allen updates reporters about the ongoing response efforts to the BP Deepwater Horizon oil spi...
National Incident Commander Ret. Coast Guard Adm. Thad Allen updates reporters about the ongoing response efforts to the BP Deepwater Horizon oil spill Tuesday, July 13, 2010 in Houston. (AP Photo/David J. Phillip)
APTOPIX Gulf Oil Spill
In this July 12, 2010 photo, an oil skimming vessel is seen at sunset nears on the Gulf of Mexico near the coast of Louisiana. (AP Photo/Patrick Sema...
In this July 12, 2010 photo, an oil skimming vessel is seen at sunset nears on the Gulf of Mexico near the coast of Louisiana. (AP Photo/Patrick Semansky)
Gulf Oil Spill
Vessels operate in the area of the Deepwater Horizon disaster on the Gulf of Mexico, Tuesday, July 13, 2010. BP officials have placed a containment c...
Vessels operate in the area of the Deepwater Horizon disaster on the Gulf of Mexico, Tuesday, July 13, 2010. BP officials have placed a containment cap over the leak in hopes that the flow of oil will be diminished. (AP Photo/Dave Martin)
Gulf Oil Spill
A pelican cleans its feathers while resting on oiled shrubs on Cat Island off the coast of Louisiana on Tuesday, July 13, 2010. (AP Photo/Judi Botto...
A pelican cleans its feathers while resting on oiled shrubs on Cat Island off the coast of Louisiana on Tuesday, July 13, 2010. (AP Photo/Judi Bottoni)
Gulf Oil Spill
A tug boat pulling a barge passes vessels assisting in the Deepwater Horizon oil well leak on the Gulf of Mexico near the coast of Louisiana Tuesday,...
A tug boat pulling a barge passes vessels assisting in the Deepwater Horizon oil well leak on the Gulf of Mexico near the coast of Louisiana Tuesday, July 13, 2010. (AP Photo/Patrick Semansky)
APTOPIX Gulf Oil Spill
The Discoverer Inspiration drilling platform operates in the area of the Deepwater Horizon disaster on the Gulf of Mexico, Tuesday, July 13, 2010. BP...
The Discoverer Inspiration drilling platform operates in the area of the Deepwater Horizon disaster on the Gulf of Mexico, Tuesday, July 13, 2010. BP officials have placed a containment cap over the leak in hopes that the flow of oil will be diminished. (AP Photo/Dave Martin)
Gulf Oil Spill
Vessels operate in the area of the Deepwater Horizon disaster on the Gulf of Mexico, Tuesday, July 13, 2010. BP officials have placed a containment c...
Vessels operate in the area of the Deepwater Horizon disaster on the Gulf of Mexico, Tuesday, July 13, 2010. BP officials have placed a containment cap over the leak in hopes that the flow of oil will be diminished. (AP Photo/Dave Martin)
Gulf Oil SPill
In a photo made from video provided by BP PLC, oil emerges from the damage wellhead Wednesday morning July 14, 2010 at 1:04 a.m. EDT in the Gulf of M...
In a photo made from video provided by BP PLC, oil emerges from the damage wellhead Wednesday morning July 14, 2010 at 1:04 a.m. EDT in the Gulf of Mexico. A pivotal moment in the Gulf oil crisis hit an unexpected snag Tuesday evening when officials announced they needed more time before they could begin choking off the geyser of crude at the bottom of the sea. (AP Photo/BP PLC) NO SALES
BP is temporarily letting oil pour out of a second pipe on its untested cap as part of preparations for closing all the valves to see how well it can contain the oilwell's flow.
The federal government's point man on the disaster, Thad Allen, says all the pipes may be closed later today. That would start a 48-hour experiment to see if the massive capping stack can stop the oil without blowing a new hole in the well.
BP late Wednesday shut down two of the three valves that control the flow of oil through the cap. But a leak discovered in a pipe overnight required a fix and the pipe was replaced early Thursday. That sent BP back to the start of preparing for the test, including by reopening one of the two closed valves.
