The company ran "injectivity tests" earlier today to determine whether the blown-out well could withstand the pressure from the procedure, which is meant to begin killing the troubled oil well for good. The idea is to use heavy mud and cement to push the oil back into its reservoir, more than two miles below the water's surface.
The latest effort to kill the blown-out well came amid word that new federal estimates make the Deepwater Horizon disaster the world's worst-ever accidental oil spill.
Back in June, the Gulf of Mexico oil spill became America's worst ever, exceeding the volume of crude released in the 1989 Exxon Valdez disaster. But new federal numbers released Monday show that nearly 5 million barrels of oil have gushed out of BP's damaged well since an April 20 explosion killed 11 rig workers. That means the Deepwater Horizon spill is much larger than what was previously believed to be the world's largest accidental spill, the 1979 Ixtoc I leak in Mexico's Bay of Campeche, which spilled 3.3 million barrels.
"We've never had a spill of this magnitude in the deep ocean," Ian R. MacDonald, a professor of oceanography at Florida State University, told The New York Times. The new figures were reported by several news agencies.
"These things reverberate through the ecosystem," MacDonald said. "It is an ecological echo chamber, and I think we'll be hearing the echoes of this, ecologically, for the rest of my life."
The largest oil spill in history is still believed to have been Iraqi troops' intentional release of an estimated 8 million barrels into the Persian Gulf during the 1991 Gulf War.
New Threat Looms for Seafood
Video: How "Static Kill" Works
Timeline: Saving Sea Turtles
Will Spill Oil Fill Your Gas Tank?
Who Decides if Seafood Is Safe?
Full Coverage: AOL News
Full Coverage: Politics Daily
According to the new federal estimates, only about 800,000 barrels of the oil that has leaked into the Gulf of Mexico -- about one-fifth of the total -- has been cleaned up. The rate of oil flowing from the well has slowed over time, the figures show. At first, it was leaking about 62,000 barrels of oil each day in late April, but then slowed to about 53,000 barrels daily before the well was capped last month.
The static kill involves pumping heavy drilling mud into the well's 150,000-pound containment cap, and then possibly sealing it with cement through a relief well the company has been digging for months. It's similar to a tactic that failed in May, the so-called "top kill," which BP tried to pull off while thousands of gallons of crude were still spewing out of the damaged well shaft. But now that the flow has basically been halted, engineers believe the tactic has a better chance of success.
For the past several weeks, BP has described the static kill as only half the solution. The other half, officials have said, is a plan to plug the damaged well from the bottom using two nearby relief wells. A similar process involving the pumping of heavy drilling fluids and cement would also be carried out below the well, sealing it off from the top and bottom.
But officials said Monday that depending on how successful the static kill is, BP might not need to pump cement through the relief wells too. Instead, they could be used as a tool to ensure that the static kill is sufficient.
"Even if we were to pump the cement from the top, we will still continue on with the relief well and confirm that the well is dead," BP Senior Vice President Kent Wells said, according to The Associated Press. Either way, he said, "we want to end up with cement in the bottom of the hole."
"Precisely what the relief wells will do remains to be seen, given what we learn from the static kill," BP spokesman Daren Beaudo told the AP. "Can't predict it for certain."
The static kill is expected to run through Wednesday, when a decision will be made about whether a second sealing operation is needed, officials said. Meanwhile the closest relief well, which has already been drilled within five feet of the damaged oil pipe, will make contact with it sometime between Aug. 11 and Aug. 15, the BBC reported. If a so-called "bottom kill" operation is needed, that could take days or weeks.
Gulf Oil Spill
A crew member looks out at the California Responder oil skimming vessel from the deck of the Pacific Responder in the Gulf of Mexico near the coast of Louisiana Monday, July 12, 2010. The vessels sailed from their home ports in California to the Gulf of Mexico to assist in the containment of oil leaking from the Deepwater Horizon oil well. (AP Photo/Patrick Semansky)
Vessels assisting in the containment of oil from the Deepwater Horizon oil well leak are seen from the Pacific Responder oil skimming vessel in the Gulf of Mexico near the coast of Louisiana Monday, July 12, 2010. (AP Photo/Patrick Semansky)
Crew members connect a hose to an intake for recovered oil while preparing for skimming operations on the Pacific Responder oil skimming vessel in the Gulf of Mexico near the coast of Louisiana Monday, July 12, 2010. The vessel sailed from its home port in the San Francisco Bay Area to the Gulf of Mexico to assist in the containment of oil leaking from the Deepwater Horizon oil well. It arrived near the leak site this morning and is awaiting orders from on-water coordinators. (AP Photo/Patrick Semansky)
The New Jersey Responder oil skimming vessel is seen on the Gulf of Mexico near the coast of Louisiana Monday, July 12, 2010. (AP Photo/Patrick Semansky)
Senior master responder Jeff Bramlett walks past rolled-up oil booms while preparing for oil skimming operations on the deck of the Pacific Responder oil skimming vessel in the Gulf of Mexico near the coast of Louisiana Monday, July 12, 2010. The vessel sailed from its home port in the San Francisco Bay Area to the Gulf of Mexico to assist in the containment of oil leaking from the Deepwater Horizon oil well. It arrived near the leak site this morning and is awaiting orders from on-water coordinators. (AP Photo/Patrick Semansky)
Supervisor Wade Falany handles an oil suction hose while preparing for skimming operations on the deck of the Pacific Responder oil skimming vessel in the Gulf of Mexico near the coast of Louisiana Monday, July 12, 2010. The vessel sailed from its home port in the San Francisco Bay Area to the Gulf of Mexico to assist in the containment of oil leaking from the Deepwater Horizon oil well. It arrived near the leak site this morning and is awaiting orders from on-water coordinators. (AP Photo/Patrick Semansky)
In this image taken from video provided by BP PLC, oil flows from the top of the transition spool at 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
Deck hand Martin Mayorga carries netting while preparing for skimming operations on the deck of the Pacific Responder oil skimming vessel in the Gulf of Mexico near the coast of Louisiana Monday, July 12, 2010. The vessel sailed from its home port in the San Francisco Bay Area to the Gulf of Mexico to assist in the containment of oil leaking from the Deepwater Horizon oil well. It arrived near the leak site this morning and is awaiting orders from on-water coordinators. (AP Photo/Patrick Semansky)
Supervisor Wade Falany handles a rope while preparing for oil skimming operations on the deck of the Pacific Responder oil skimming vessel in the Gulf of Mexico near the coast of Louisiana Monday, July 12, 2010. The vessel sailed from its home port in the San Francisco Bay Area to the Gulf of Mexico to assist in the containment of oil leaking from the Deepwater Horizon oil well. It arrived near the leak site this morning and is awaiting orders from on-water coordinators. (AP Photo/Patrick Semansky)
In this image taken from video provided by BP PLC, the new containment cap, left, is lowered toward the site of the Deepwater Horizon oil spill, right, as a remotely operated vehicle operates in between the two 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