Oil is no longer spewing into the Gulf of Mexico -- at least temporarily -- as BP Plc said it choked off the flow from its undersea well that ruptured in April and caused the worst offshore oil spill in US history.
BP said it stopped the leak on Thursday with the tight-sealing containment cap installed three days earlier atop its blown-out well, and awaited on Friday the results of tests on whether the well remains intact.
That's a key issue as the British energy giant moves to plug the leak permanently with a relief well intended to intersect the ruptured well -- which extends 2.5 miles under the seabed -- and seal it with mud and cement next month.
BP's US shares closed up 7.6% on Thursday after it announced it had shut off the flow of oil from the well, and traders were eager to see if the rally would continue in Friday trading in London.
Oil had spurted from the well a mile below the ocean surface for more than three months, causing a massive oil spill that led to an economic and environmental catastrophe along the US Gulf Coast.
BP, which has failed several times in its efforts to end the leak, managed to stop the flow of oil as it conducted a test in which it closed valves and vents on the containment cap.
“I think that it is a positive sign,” said US President Barack Obama, whose public approval ratings fell as the oil spill crisis dragged on. He cautioned that “we're still in the testing phase.”
The test, which could last up to 48 hours, gauges pressure in the well to assess its condition. Officials said the test would show whether the cap can safely shut off the flow from the well if oil-capture vessels at the surface must disconnect, for example in the event of a hurricane.
“It's a great sight but it's far from the finish line,” Doug Suttles, a senior BP executive, told reporters.
“We're encouraged by this development, but this isn't over,” said retired Coast Guard Admiral Thad Allen, the US government's point man on the spill.
The Coast Guard said BP likely would release the flow of oil again after the test is done -- siphoning it to ships on the ocean surface in an improved system able to handle up to 80,000 barrels a day until a relief well seals the well permanently.
That should be more than enough to capture the whole well output, as estimates put the spill rate between 35,000 barrels (1.47 million gallons/5.56 million liters) and 60,000 barrels (2.5 million gallons/9.5 million liters) a day.
The Coast Guard calls the containment cap at best a temporary fix to the leak while BP finishes the two relief wells it is drilling.
The test is intended to determine whether the structure of the well is damaged or intact. Allen compared the test to placing one's thumb over the end of a garden hose -- if the pressure does not rise, that means there is a leak somewhere.
Regarding the BP well, a build-up of pressure would signal the well is intact, which would make it easier to seal it with the relief wells.
The Gulf spill has soiled hundreds of miles (km) of shoreline, shut down about a third of Gulf fisheries and hurt tourism and fishing in all five US Gulf states. It has also created problems for Obama as the government works to respond to the crisis while area residents struggle financially.
The news that BP had finally stopped the leak -- at least during the test -- was a bit of good news for the British company, which has seen its share value plummet and reputation battered since the April rig explosion that killed 11 workers and led to the spill of millions of gallons of oil.
There also was fresh hope in battered coastal communities.
“I tell you what, we needed that,” said Jimmy Thibodaux, a resident of the small southern Louisiana town of Cut Off. (Reuters)