BP and top US government officials faced a tough decision yesterday on whether to go ahead with a crucial test that could allow the leaking Gulf of Mexico oil well to be sealed.
The pressure test aimed at evaluating the integrity of the wellbore, which stretches down four kilometres below the seabed, involves shutting off the valves on a 75-tonne cap freshly installed on top of the leaking well.
High pressure readings would allow the three valves to remain shut and the well would effectively be sealed, but low ones could mean there is a hole somewhere in the casing of the well where oil is escaping.
“One of the concerns raised yesterday is, somehow through this testing process could the casing be damaged?” said BP chief operating officer Doug Suttles.
“That’s what we’re examining with the experts right now to make sure that we don’t believe that’s the case and to confirm that. If we did think that could happen, we wouldn’t proceed with the test.”
Admiral Thad Allen, the former Coast Guard chief leading the US response to the disaster, delayed the high-stakes procedure on Tuesday for 24 hours for the further analysis to be conducted.
He was holding a make-or-break meeting yesterday with top experts and officials, including Energy Secretary Steven Chu, a Nobel Prize-winning physicist, to decide whether or not to proceed.
“I do not consider this to be some permanent setback,” said White House spokesman Robert Gibbs, confirming that the meeting was under way.
After months of environmental and economic ruin, the final deliberations were a further agonising delay for anxious Gulf residents whose livelihoods depend on the oil being stopped and the huge surface mess being cleared up.
If the all-clear is given and once the valves are closed, no oil will be streaming into the Gulf for the first time since the Deepwater Horizon rig sank 83 days ago.
The process – expected to last between six and 48 hours – must be done gradually as a massive pressure shift could send oil shooting up through a new leak on the sea floor, further aggravating the worst oil spill in US history.
Mr Allen has said that pressure readings anywhere between 8,000 and 9,000 pounds per square inch would indicate that the casing of the wellbore is secure.
Less than 6,000 psi would indicate oil was seeping out of the external casing of the well. In that case the valves would be reopened immediately to reduce the risk of doing further damage to the well or causing a new gusher.
Although containment operations would have to resume at that point, officials say the new cap gives them the ability to capture all the leaking oil in a matter of days.
Officials have also said that drilling on a relief well that is now only 1.2 metres away from the leaking well would be suspended if and when the integrity test is carried out.