Officials have long insisted that a relief well was the only surefire way to kill the oil leak at the bottom of the Gulf of Mexico, but with engineers only feet away from completing a pair of them they're now wrestling with how exactly to use them.
Crews planned testing this evening to determine whether to proceed with a plan - called a "static kill" - to pump mud and perhaps cement down the throat of the mile-deep busted well. The role of the relief well, plus a backup one dug at White House insistence, was to do the same from the bottom of the well and insure that the oil would stay in its vast undersea reservoir.
BP PLC Senior Vice President Kent Wells said Monday that engineers may pump cement directly into the busted well through the failed blowout preventer via a surface ship, rather than wait for the relief well's planned completion later this month.
That idea isn't new - but BP has never before indicated it might forgo use of the relief well altogether in direct attempts to plug the leak.
"Precisely what the relief wells will do remains to be seen given what we learn from the static kill," BP spokesman Daren Beaudo said. "Can't predict it for certain."
Either way, Wells said, "We want to end up with cement in the bottom of the hole."
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 the second well May 16. The first well is now only about 100 feet from the target, and Wells said it could reach it by Aug. 11.
The British oil giant said there's no doubt the relief wells, which can cost about $100 million each, would be used in some fashion. Mud and cement could be pumped down to plug the reservoir, or it could simply be used to "confirm" that the static kill worked, Beaudo said.
BP didn't fully explain why, after so much time, money and effort, the company was unclear on the role a relief well would play.
The company could be more worried than it has said publicly about debris found in the relief well after it was briefly capped as Tropical Storm Bonnie passed last week, said Louisiana State University environmental sciences professor Ed Overton.
Plus, trying to seal the well from the top gives BP two shots at ending the disaster, Overton said.
"Frankly, if they can shut it off from the top and it's a good, permanent seal, I'll take it," Overton said. "A bird in the hand at this point is a good thing with this deal."
Engineers hoped to complete a final test by Monday evening to determine whether to proceed with the static kill. If the test is successful, Wells said, engineers would spend most of Tuesday and likely part of Wednesday slowly pumping the heavy mud down the well, which has spewed as much as 184 million gallons.
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.
"The only thing that separates the oil from the sea now is the valve. This puts thousands of feet of mud and cement in between," said Eric Smith, associate director of the Tulane Energy Institute. "The idea is to have as many barriers as possible between the ocean and the reservoir. We're adding an extra level of safety."
The whole procedure is still set to be completed by late August despite a brief evacuation for Bonnie.