BP works to fix valve leak on cap that could choke off oil leaking into Gulf of Mexico

BP works to fix valve leak before choking oil flow

NEW ORLEANS — BP engineers worked Thursday to repair a leak found on a line attached to the new cap placed on top of its busted well in the Gulf of Mexico before continuing its delicate operation to stop the flow of crude.

BP isolated the leak Wednesday night and had begun repairing it. It wasn’t clear how it would affect the timing of the operation, or whether oil continued to be slowly closed off into the cap.

The new, tighter cap had been placed on the busted well Monday, but the operation to start shutting off valves to choke off the oil was abruptly halted for about a day. BP needed time to allay government fears that the disaster could be made worse by going forward with the tests, which are needed to determine whether the temporary cap can withstand the pressure and contain the oil.

The new cap along with vessels at the surface meant to siphon up the crude are considered the best hope to stop oil from continuing to foul the Gulf until two relief wells can be drilled that will allow the busted well to be plugged for good. The crisis began April 20 when the BP-leased Deepwater Horizon rig exploded, killing 11 workers.

In the 12 weeks since, an estimated 92 million to 182 million gallons of oil have flowed into the Gulf.

The latest effort to halt the tide of oil — after repeated failures — began with BP shutting off pipes that were funneling some of the oil to ships on the surface so the full force of the gusher went up into the cap. Then deep-sea robots began slowly closing, one at a time, three openings in the cap that let oil pass through. Ultimately, the flow of crude will be blocked entirely.

All along, engineers were watching pressure readings to learn whether the well is intact. The first two valves shut off like a light switch, while the third works more like a dimmer and takes longer to close off. The leak was found in the line attached to the dimmer switch, but live video footage showed that oil previously spewing from other sources on the cap remained closed off.

Retired Coast Guard Adm. Thad Allen, the Obama administration’s point man on the disaster, said a committee of scientists and engineers will monitor the results and assess every six hours, and end the test after 48 hours to evaluate the findings.

“I was gung-ho for this test and I remain gung-ho for this test,” he said Wednesday.

If the cap works, it will enable BP to stop the oil from gushing into the sea, either by holding all the oil inside the well machinery like a stopper or, if the pressure is too great, channeling some through lines to as many as four collection ships.

The cap — a 75-ton metal stack of lines and valves — was lowered onto the well on Monday in hopes of either bottling up the oil inside the well machinery, or capturing it and funneling it to the surface. But before BP could test the equipment, the government intervened because of concerns about whether the buildup of pressure from the gushing oil could rupture the walls of the well and make the leak worse.

“We sat long and hard about delaying the tests,” Allen said. He said that the pause was necessary in the interest of the public, the environment and safety, until officials were convinced the test could go forward.

Allen said the testing will also offer insight into the other, more permanent solution to the fix: two relief wells intended to plug the gusher from deep underground. The mapping of the sea floor that was done to prepare for the well cap test and the pressure readings will also help them determine how much mud and cement will be needed to seal off the well.

Drill work was stopped on one relief well because it was not clear what effect the testing of the cap could have on it. Work on the other relief well had already been stopped according to plan.

The government estimates 1.5 million to 2.5 million gallons are leaking every day.

The latest effort to control the gushing well follows a string of failed attempts by BP to contain the leak, including the use of a giant concrete-and-steel box that quickly became encased in ice-like crystals; a colossal siphon tube that trapped very little oil; and an effort to jam the well by pumping in mud and shredded rubber.

Online:

BP underwater video: bit.ly/bwCXmR

Weber reported from Houston. Associated Press writers Matthew Daly in Washington, Tom Breen in New Orleans, Matt Brown in Violet, La., Holbrook Mohr in Empire, La. and Jay Reeves in Bayou La Batre, Ala., contributed to this report.