“The Macondo 252 well is effectively dead,” said National Incident Commander Thad Allen in a statement today (Sep 19, 2010 - n.d.R. TA). BP completed its last pressure test on the plugs at 5:54 a.m. local time before declaring the well sealed, according to the statement.

The 87-day spill, triggered by an April 20 rig explosion that killed 11 workers, tainted hundreds of miles of U.S. coastline. It also wiped out more than $70 billion of BP’s market value, brought new drilling in the Gulf to a standstill and cost Chief Executive Officer Tony Hayward his job. About 400 lawsuits are pending, and the trial judge overseeing those predicted hundreds more will be filed.

“The whole industry is terrified it could happen to them,” Peter Hitchens, an analyst for Panmure Gordon UK Ltd. in London, said in an interview. “The whole way we drill wells could actually change. They’re going to take a lot longer. They’re going to be a lot more scrutinized.”

Another series of plugs probably will be required by the U.S. Bureau of Ocean Energy Management, Regulation and Enforcement before BP can abandon the well, Daren Beaudo, a company spokesman, said in an interview before today’s announcement.

BP Response

BP has spent at least $8 billion responding to the spill. The well, about 40 miles (64 kilometers) off the Louisiana coast, gushed more than 4 million barrels of oil into the Gulf. No crude or gas has leaked since BP capped the well July 15.

The disaster revealed that BP was unprepared to stanch a gusher 5,000 feet (1,524 meters) below the ocean surface, where pressure turns natural gas into pipe-clogging slush. BP took 87 days to design, build and deploy a 75-ton cap that stopped the flow after a series of failures.

Exxon Mobil Corp., Chevron Corp., ConocoPhillips and Royal Dutch Shell Plc have pledged $1 billion to create a system to capture oil from underwater blowouts.

Weather slowed BP’s efforts to intercept the well. On June 25, the company said it would take a few weeks for the relief drilling to reach the level where it would enter Macondo.

Interception occurred Sept. 16, at 17,997 feet (5,485 meters) below the sea surface, BP said a day later.

Blaming Transocean

The well’s blowout preventer, a stack of valves designed to stop the sort of surge of oil and gas that led to the rig explosion, is at a government site in New Orleans for testing and inspection by the U.S. Justice Department and others.

BP expects to demobilize a fleet of drilling rigs and other ships that have been stationed at the well for months now that the well is permanently plugged, Beaudo said. That fleet has included two drillships, three drilling rigs, production vessels, tankers and ships that operated underwater robots.

BP on Sept. 8 published a 234-page report on the causes of the explosion on the Deepwater Horizon drilling rig, saying that its own managers and contractors involved with the well made mistakes that contributed to the disaster. The company blamed many of the errors onTransocean Ltd., which owned the Deepwater Horizon, and on service providers such as Halliburton Co.

BP’s report concealed the well’s “fatally flawed” design, which “set the stage” for the explosion, Geneva-based Transocean said Sept. 8. The driller cited a series of cost- savings decisions by BP that added risk.

Cathy Mann, a spokeswoman for Houston-based Halliburton, said the report had “substantial omissions and inaccuracies” and that BP dictated design and testing procedures for the well.

Anadarko Petroleum Corp., based near Houston, has a 25 percent stake in Macondo. A unit of Mitsui Oil Exploration Co., which is 70 percent owned by Japan’s Mitsui & Co., holds a 10 percent interest. BP was operator and held a 65 percent stake.

To contact the reporter on this story: Jim Polson in New York at jpolson@bloomberg.net;Christian Schmollinger in Singapore at christian.s@bloomberg.net;