BP likely won't put the final plug in its blown-out Gulf of Mexico oil well until September to allow replacement of a critical piece of seabed equipment, the top U.S. oil spill official said Thursday.
Concern over how to safely proceed after pouring cement in the Macondo well from the top, as well as weather delays, pushed the last step past the U.S. Labor Day holiday on Sept. 6 from mid-August, retired Coast Guard Admiral Thad Allen said at a briefing in Washington.
"As we get to the end, we are very close to putting this well away," Allen said. "I think none of us wants to make a mistake at this point."
Allen on Thursday authorized BP [BP 36.24 -1.06 (-2.84%) ] to craft a plan to retrieve the failed blowout preventer atop the Macondo well about a mile beneath the ocean surface and replace it with another before drilling resumes on the relief well.
The blowout preventer failed when the well ruptured on April 20, causing an explosion aboard the Deepwater Horizon drilling rig that killed 11 workers.
An estimated 4.9 million barrels of oil spewed into the Gulf, contaminating wetlands, fishing grounds and beaches from Louisiana to the Florida Panhandle.
No oil has leaked into Gulf waters since July 15, when BP placed a provisional cap over the wellhead.
Allen said it is key evidence in investigations of the disaster, including those by the U.S. Department of Justice and a joint probe by the Coast Guard and the U.S. Bureau of Ocean Energy Management.
"We do not want to have damage to that blowout preventer if we can avoid it because it's going to be material evidence of exactly what happened during the event itself," Allen said.
In the meantime, BP is testing pressure in the well and seabed equipment, he said.
The relief well is about 50 feet from its target near the bottom of the Macondo well about 13,000 feet beneath the seabed.
BP engineers and government scientists were concerned cement injected from the top may have trapped up to 1,000 barrels of oil in the space between the well pipe and the surrounding rock layers.
They want to make sure pumping in mud and cement through the relief well will not increase pressure and force that oil up, where it could leak into the sea or damage the blowout preventer.