Mud plugging 'may stem oil leak'
BP chiefs have said they may be able to stem the Gulf of Mexico oil spill with lines running from a ship to the blown-out well a mile below, after months of insisting that a pair of costly relief wells were the only sure way to kill the leak.
As crews planned testing to determine whether to proceed with a "static kill" to pump mud and perhaps cement down the throat of the well, BP senior vice president Kent Wells said if it was successful the relief wells may not be needed after all, to do the same weeks later from the bottom.
The primary relief well, near completion, will still be finished and could be used simply to ensure the leak is plugged, Mr Wells said.
"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," he said. Either way, "we want to end up with cement in the bottom of the hole", he said.
Before the effort can begin, engineers must probe the broken blow-out preventer with an oil-like liquid to decide whether it can handle the static kill process. They delayed the test after a small leak was discovered in the hydraulic control system.
The US government and company executives have long said the relief wells, which can cost about £63 million each, may be the only way to make certain the oil is contained to its vast under-sea reservoir.
Meanwhile, a government task force estimated that about 172 million gallons of oil made it into the Gulf between April and mid-July, when a temporary cap bottled up all the oil. The earlier estimate had been as high as 184 million gallons.
The company began drilling the primary, 18,000ft relief well on May 2, 12 days after the Deepwater Horizon rig exploded and killed 11 workers, and a second back-up well on May 16.
The first well is now only about 100 feet from the target, and Mr Wells said it could reach it as early as August 11.
Retired Admiral Thad Allen, the US government's point man on the spill response, said the focus was now on making sure the static kill was successful. But he warned that government officials did not see it as "the end all, be all until we get the relief well done".