BP engineers began testing the blown-out Gulf of Mexico well Tuesday to determine whether it can withstand a planned attempt to pump heavy drilling mud down its throat in hopes of choking it for good, the company said.
Engineers began probing the well with an oil-like liquid around 1 p.m. Central time in a test that, if successful, will allow engineers to spend several days pumping the mud down the well.
Once the hours-long testing is declared complete, crews will then spend several hours analyzing the results before launching the latest effort, dubbed the static kill, BP said.
"This is a really positive step forward," retired Coast Guard Adm. Thad Allen said earlier of the pending static kill. "It's going to be good news in a time where that hasn't been very much good news, but it shouldn't be a cause for premature celebration."
The static kill is meant as insurance for the crews that have spent months fighting the spill. The only thing keeping oil from blowing into the Gulf at the moment is an experimental cap that has held for more than two weeks but was never meant to be permanent.
BP officials had said Monday that the static kill alone -- which involves slowly pumping mud down lines running from a ship to the blown-out well a mile below -- may plug the oil leak. But the company said there's no way to tell until the relief wells engineers have been digging for three months is complete.
Allen, the government's point man on the spill response, added earlier Tuesday that there "should be no ambiguity" that the primary relief well -- which could be completed as early as Aug. 11 -- will be finished, regardless. And the only surefire way to make certain the well is permanently plugged is to later fill it from below with mud and cement in a so-called "bottom kill," he said.
The testing was supposed to be completed Monday, but a minor leak discovered in the hydraulic control system pushed back the diagnostics until Tuesday. Allen said leaks have been repaired.
While the static kill could take days to complete, mostly because it involves the slow pumping of mud, Allen said crews should know within hours of its start whether the process is working.
It's important to begin soon, he said, with the peak hurricane season just around the corner. Tropical Storm Colin formed far out in the Atlantic on Tuesday, but early forecasts put it on a track off the East Coast rather than the Gulf.
And while diagnostic tests show that the 75-ton cap that has bottled up the oil since mid-July is sound, the static kill would give scientists more confidence the well won't leak again, he said.
"The quicker we get this done, the quicker we can reduce the risk of some type of internal failure" of the massive cap, he said.
A federal task force said Monday that about 172 million gallons of oil made it into the Gulf between April and July 15, when the temporary cap contained all the oil.
The task force said about 206 million gallons actually gushed out of the well, but a fleet of boats and other efforts were able to contain more than 33 million. The 172 million gallons is on the high end of recent estimates that anywhere from 92 million to 184 million gallons had gushed into the sea.
Judging by the latest estimate, BP could be fined up to $5.4 billion under the Clean Water Act, or as much as $21 billion if it is found to have committed gross negligence or willful misconduct.
The high-end fine would drop to around $17.6 billion if the government credits BP for the oil it has recovered, while the low-end fine would be around $4.5 billion.
Any fines would be on top of the compensation BP has agreed to pay to thousands of people harmed by the spill. Under pressure from the White House, the company set up a $20 billion escrow fund to pay all claims, including environmental damages and state and local response costs.
The company began drilling the primary, 18,000-foot relief well May 2, 12 days after the Deepwater Horizon rig exploded and killed 11 workers, and a second backup well May 16. The first well is now only about 100 feet from the target and is expected to be completed later this month.
BP and federal officials have managed to contain large parts of the spill through skimmers, boom and chemical dispersants meant to break up the oil.
Federal regulators have come under fire from critics who say that BP was allowed to use excessive amounts of the dispersants, but government officials counter that they have helped dramatically cut the use of the chemicals since late May.
The Environmental Protection Agency released a study Monday concluding that when mixed with oil, chemical dispersants used to break up the crude in the Gulf are no more toxic to aquatic life than oil alone.
As businesses along the coast continued to clamor for relief from losses caused by the spill, BP said it created a special team to reduce paperwork and speed up payments to "businesspeople who are suffering."
Contributing to this report were Associated Press writers Ramit Plushnick-Masti in Houston, Jeffrey Collins and Harry R. Weber in New Orleans, and Matthew Daly in Washington.