BP PLC claimed a big victory in its efforts to kill its blown-out oil well, fueling optimism that the three-month oil drama in the Gulf of Mexico was finally entering its closing stages.
The success of BP's "static kill" operation, in which heavy drilling mud was pumped into the runaway well and pushed the gushing oil back into the reservoir, coincided with a government report that said much of the spilled oil is now gone.
U.S. President Barack Obama said the "long battle to stop the leak and contain the oil is finally close to coming to an end."
Coast Guard Adm. Thad Allen, who heads the federal oil-spill response effort, said late Wednesday that he has authorized BP to attempt to seal the well for good, pumping cement through the same pathways it used for the static kill. BP said it will begin the process Thursday.
The operation, though, should not hinder efforts to complete a relief well that would intersect the damaged well and pump cement from the bottom, in case it Is needed.
Federal officials, including Mr. Allen, have stressed that the only permanent solution to the spill is a relief well, which will be completed by mid-August. But if cementing the well from the top works, the final demise of the well could occur sooner than that.
A report by U.S. scientists released Wednesday said that burning, skimming and direct recovery from the wellhead had removed one-quarter of the oil spilled into the Gulf, another quarter had naturally evaporated or dissolved, and 24% was dispersed as microscopic droplets into Gulf waters.
It said the rest—26%—is either on or just below the surface as light sheen and tar balls, has washed ashore or been collected from the coastline, or is buried in sand and sediments.
The success of the static kill marks a breakthrough in BP's attempts to subdue a well that the government estimates has spewed nearly five million barrels of crude into the Gulf of Mexico.
It comes more than three months after the Deepwater Horizon drilling rig exploded off the coast of Louisiana, killing 11 men and triggering what has now been acknowledged as the world's worst accidental oil spill at sea.
The spill has been a catastrophe for the economy of the Gulf Coast and badly weakened BP, whose chief executive Tony Hayward was forced to step down over the disaster.
The company is facing billions of dollars in fines and penalties for the pollution caused by the spill, as well as huge claims for damages. In June, it suspended its dividend and agreed to set aside $20 billion in an escrow account to compensate victims of the spill.
But in recent weeks, the tide appears to have turned for BP—particularly since July 15, when it installed a new, more tightly fitting cap on the well and oil stopped leaking into the Gulf. Its share price has recovered, and it is a third of the way toward its goal of raising $30 billion from asset sales to help it meet the cost of the spill.
Also, a threat posed by legislation that could have blocked the oil major from winning new drilling permits in U.S. waters was put on hold this week when Senate Majority Leader Harry Reid delayed action on an energy bill until after Congress returns from its summer recess in mid-September.
Over the course of eight hours on Tuesday, BP's engineers pumped hundreds of barrels of heavy drilling mud into the well from vessels on the surface. Gradually, the pressure of the mud equaled the upward pressure of the oil and gas, which was forced back into the reservoir.
The well "appears to have reached a static condition," BP said in a statement, describing it as a "significant milestone." It said it is now monitoring the well to ensure it remains under control, and may decide to pump in more mud depending on the results.
BP officials have stressed a definitive solution will only come with the relief well,