Pressure readings have been less than ideal from the new cap shutting oil into BP's busted well, but the crude will remain locked in while engineers look for evidence of whether there is an undiscovered leak, the federal pointman for the disaster said Friday.
Retired Coast Guard Adm. Thad Allen said on a conference call that pressure readings from the cap have not reached the level that would show there are no new leaks in the well.
Allen said BP's test of the cap, which started 24 hours previously by shutting three valves and stopping the flow of oil into the water, would continue for at least 6 hours. It was scheduled to last up to 48 hours.
He said the developments were "generally good news" but needed close monitoring.
Allen said there are two possible reasons being debated by scientists on the project for why the pressure hasn't risen as high as desired: The reservoir that is the source of the oil could be depleting after a three-month spill, or there could be an undiscovered leak somewhere down in the well.
"We don't know because we don't know the exact condition of the well bore," Allen said.
He said the test will go ahead for another 6-hour period before being reassessed to see if BP needs to reopen the cap and go back to piping some of the oil to ships on the surface.
If it were reopened, Allen said, "There's no doubt there would be some discharge into the environment."
Pressure readings after 24 hours were about 6,700 pounds per square inch and rising slowly, Allen said, below the 7,500 psi that would clearly show the well was not leaking. He said pressure continued to rise between 2 and 10 psi per hour.
He said a seismic probe of the surrounding sea floor found no sign of a leak in the ground, one of the major concerns because oil erupting into the surroundings would be harder to contain and could weaken the well before it is plugged for good.
The cap is a temporary measure. Even if it holds, BP needs to plug the gusher with cement and mud deep underground, where the seal will hold more permanently than any cap from above could.
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