BP studies need for relief well after damaged shaft cemented shut
Oil giant BP was conducting tests Thursday to determine whether to continue drilling a relief well that has long been viewed as the last step in permanently plugging the gushing oil well below the Gulf of Mexico, dpa reported.
But there was a small possibility that the leaking well has been fully plugged by an earlier cementing procedure, already ending the saga to plug the leak that since April has caused the worst oil spill in US history.
"We may be the victims of our own success here," said Coast Guard Admiral Thad Allen, who is coordinating the US government's response to the disaster.
There was a "low probability" that the relief well would not be completed.
A decision would be made late Thursday or early Friday whether to proceed with the relief well, which is currently within about 10 metres of the leaking reservoir. The drilling was interrupted earlier this week because of a storm passing over the Gulf.
There has been no oil gushing into the ocean since BP secured a tight-fitting cap over the damaged well on July 15, and last week the company successfully pushed cement down the leaking pipe to more permanently seal the leak.
The relief well is intended to inject more cement into the shaft from the bottom up, by drilling into the lower annulus and fully sealing the leak. But Allen said there was a possibility the top-down approach had already done the job.
"One way or the other the annulus will be sealed. Our question is: did it already happen?" Allen said. "That's why we're conducting the test."
About 4.9 million barrels of oil are estimated to have spewed into the Gulf since April 20, washing up along the shores of four southern US states and killing wildlife in Gulf waters.