WASHINGTON — Following a day-long delay marked by intense double-checking and a briefing for President Barack Obama, the government's spill team decided to let BP begin testing the seal on a massive 75-ton pipe fitting that could finally stop the three-month gush of oil and gas from the company's failed well in the Gulf of Mexico.
The company was scheduled to begin the well integrity testing Tuesday afternoon, but was ordered by the government to stop until experts could go through all the possible side effects. In particular, they were uncertain about the condition of the well — and whether additional pressure on the new seal would force oil and gas to leak out of weak spots deep below the floor of the ocean.
The 24-hour pause was a result of "an overabundance of caution," said the national incident commander, Adm. Thad Allen.
Mostly, they feared making an already dire situation irrevocably worse, Allen said.
"This has been a substantial impact on our environment, there's been a substantial impact on the Gulf Coast, the people and the culture," Allen said. "What we didn't want to do is compound that problem by making an irreversible mistake."
A delay allowed them to incorporate the results of seismic testing, which found none of the weakness they feared, Allen said.
The integrity testing will begin by slowly closing off the well, gradually building up pressure — a process Allen described to reporters at a briefing in New Orleans using a hand-drawn diagram on a dry-erase board. The process is expected to take about 48 hours, and will be halted every six hours to examine acoustic data and pressure levels to decide whether to proceed.
Allen said drilling experts will be trying to determine whether pressure can be maintained without an effect on the wellbore and its casing. If pressure drops, that signals there's a potential weakness in the well and that oil and gas could be escaping elsewhere. They want the pressure to remain constant.
If it continues to remain stable after 48 hours, that's when they'll decide whether to move forward with activating the containment cap, Allen said.
What they learn from the integrity testing about the condition of the well will help inform how they proceed with the relief wells, which are nearing completion. The pressure readings, for example, will help them determine what kind of drilling mud to use.
Until recently, BP officials and the government have not publicized that they may be able to shut off the well in this way — a deliberate decision, said BP's senior vice president, Kent Wells.
They had always thought they might be able to kill the well using the stack that currently is funneling much of the oil to the surface for processing. But they lacked confidence until they had done additional engineering and scientific analysis, Wells said Wednesday afternoon in a technical briefing with reporters.
"We had to continue to do a lot of the analysis we did to give ourselves the confidence that we could actually pull it off," Wells said. "We chose not to talk about it a lot until we had confidence — because otherwise, we'd be talking about something that may or may not be possible."
Their greatest fear stemmed from concerns that arose during the so-called "top kill" attempt in May, which aimed to shut down the well by forcing heavy drilling mud down it to stop the oil and gas from rising. They were never able to achieve high enough levels of pressure during that process, Allen said. They thought it might be because some of the drilling mud was escaping out of the broken blowout preventer at the top of the well.
But the more alarming was the possibility it could be escaping deep in the earth, signaling a weakness in the well bore and the possibility that it was badly damaged underground. That's partly why they halted the integrity testing, Allen said. They wanted to ensure there weren't underground weakness that could lead to oil seeping out of the pipe elsewhere — or that the earth surrounding the well bore had weakened and oil and gas would make their way out of the ocean floor into the sea.
The results of seismic tests performed this week appear to discount that possibility, Allen said, and gave the team confidence to proceed with the integrity testing.
Congressional investigators on Wednesday remained concerned, and said they wanted more information about the data the company was relying on.
Rep. Ed Markey, D-Mass., who heads the Energy and Environment Subcommittee of the House Energy and Commerce Committee, sent a letter to Allen calling for BP to release information about the integrity of the wellbore and potential sea floor leaks "in light of the delayed attempt to conduct pressure tests on the new containment cap system."
Markey had originally asked for that information last month, but said Wednesday he still hasn't received any answers about the challenges the company could encounter as it attempts to permanently stop the flow of oil and gas with relief wells.
"Everyone is hoping for a successful outcome for this capping system, and for the relief wells," Markey said. "But given BP's bad track record on all of its efforts thus far, all information about the risks of these tactics must be provided to Congress and to the public."
The drilling of the relief wells — considered the most likely method to permanently seal the blownout well — also was halted during the integrity testing process.
The government has estimated that the well is spewing some 60,000 barrels a day into the Gulf. Since the Deepwater Horizon rig exploded and sank in late April, more than 200 million gallons of crude oil have been released.
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