NEW ORLEANS — A pivotal moment in the Gulf oil crisis hit an unexpected snag Tuesday evening when officials announced they needed more time before they could begin choking off the geyser of crude at the bottom of the sea.
BP and government officials did not say what prompted the decision or when the testing on the new, tighter-fitting cap would begin. The oil giant was scheduled to start slowly shutting off valves on the 75-ton metal stack of pipes and valves Tuesday, aiming to stop the flow of oil for the first time in three months.
A series of methodical, preliminary steps were completed, including mapping the seafloor. Later Tuesday, National Incident Commander Thad Allen met with the federal energy secretary and the head of the U.S. geological survey and other scientists and geologists.
“As a result of these discussions, we decided that the process may benefit from additional analysis that will be performed tonight and tomorrow,” Allen said.
Earlier Tuesday, it seemed BP was on track to test the cap, which was lowered over the blown-out well Monday night. It is designed to be a temporary fix until the well is plugged underground.
Engineers also spent hours on a seismic survey, creating a map of the rock under the sea floor to spot potential dangers, like gas pockets. It also provides a baseline to compare with later surveys during and after the test to see if the pressure on the well is causing underground problems.
It was unclear whether there was something in the results of the survey that prompted officials to delay. Earlier, BP Vice President Kent Wells said he hadn’t heard what the results were, but he felt “comfortable that they were good.”
The next phase would be to shut the openings in the 75-ton metal stack of pipes and valves gradually, one at a time, while watching pressure gauges to see if the cap would hold or any new leaks erupted.
Once the operation gets started, it could last anywhere from six to 48 hours.
If the cap works, it will enable BP to stop the oil from gushing into the sea, either by holding all the oil inside the well machinery like a stopper or, if the pressure is too great, channeling some though pipes to as many as four collection ships.
The cap is a stopgap measure that can’t keep the oil in check permanently. To end the leak for good, the well needs to be plugged at the source. BP is drilling two relief wells through the seafloor to reach the broken well, possibly by late July, and jam it permanently with heavy drilling mud and cement. After that, the Gulf Coast faces a long cleanup.
The leak began after the Deepwater Horizon offshore drilling platform exploded on April 20, killing 11 workers. As of Tuesday, the 84th day of the disaster, between 90.4 and 178.6 million gallons of oil had spewed into the Gulf.