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BP delays ‘integrity test’ on well that could lead to oil gusher’s end

Posted in Américas, Ciência & Tecnologia, Meio-Ambiente by Larissa Sauer on 14/07/2010

The Washington Post – 14/07/2010

The “integrity test” that could potentially shut down the Gulf of Mexico oil gusher has been delayed, a setback in the effort to put an end to what has been called the worst environmental disaster in U.S. history.

BP had vowed to conduct the test, which would involve closing valves on the leaking well’s newly placed cap, by midday Tuesday. As the day wore on, however, the well continued to billow black oil into the gulf.

Late Tuesday evening, retired Coast Guard Adm. Thad W. Allen, the national incident commander, announced that the test had been put off for at least a day.

As a result of discussions among government scientists and BP officials, Allen said, “we decided that the process may benefit from additional analysis that will be performed tonight and tomorrow.”

In a conference call Wednesday morning, BP Senior Vice President Kent Wells gave only a broad explanation for the halt, saying that scientists wanted to review the operation further to ensure that it produced unambiguous results.

“We wanted to make sure that there were no questions in anyone’s mind that we would learn the most from this and minimize risk,” Wells said.

Pressed for details on the perceived risks, Wells said that it’s one thing if the pressures are relieved deep in the well — oil and gas escaping into the rock formation far below the gulf floor, in other words — but “it’s a more difficult situation” if the hydrocarbons escape higher up.

It is unclear whether federal officials held up the stop sign on a test designed by BP. But Energy Secretary Steven Chu was in Houston on Tuesday and played a key role in putting an end to the “top kill” procedure in late May because of the possibility that pressurized mud could cause a lateral blow-out in the well below the gulf floor. A persistent concern for months has been that damage to the well could create additional leaks, greatly complicating efforts to kill the well.

The decision to delay the test was made by federal authorities and BP officials Tuesday afternoon, Wells said. But the delay was not announced until Allen and BP put out news releases late Tuesday night — continuing a pattern in which officials have waited many hours to inform the public of what is happening in the gulf.

In late May, for example, officials waited almost a day to reveal that they had suspended the top kill effort, and the news media continued to report, inaccurately, that the mud was being pumped into the well.

The best-case scenario for the test is that it would halt the spewing of the well. But the well could fail the test — and the gusher would return.

Federal authorities and BP engineers want to see the test create a steady increase in well pressure. This would suggest that the Macondo well is intact, and that oil and gas are not leaking into the surrounding mud and rock formations below the gulf floor. The well blew out April 20 and destroyed the Deepwater Horizon rig, killing 11 men.

If the pressure readings are too low, BP’s technicians will abandon the test and, using robotic submersibles, will reopen the valves. BP will resume trying to capture as much leaking oil as possible while continuing to drill a relief well that could kill Macondo with mud and concrete.

“Everybody hope and pray that we see high pressures here,” Wells said Tuesday. “Bear with us. Let’s do this test.”

The test could take at least two days. If authorities determine that the well can remain closed — “shut in,” to use the oil industry terminology — then Macondo would no longer pollute the gulf, and ships would stop collecting or burning oil and gas.

The relief well is getting close. It’s four feet laterally from Macondo, with about 150 feet more to drill vertically until the interception. But the target is narrow — a steel casing slightly less than 10 inches wide, with a seven-inch pipe inside. The final stages are painstaking, and BP and the government still say the bottom-kill is not likely to take place until August.

Allen set up camp in Houston on Tuesday with Energy Secretary Steven Chu for what the retired admiral had anticipated would be “a consequential day.”

The new “3 ram capping stack” was lowered without a hitch onto the reconfigured blowout preventer Monday night. A new surface ship, the Helix Producer, was also connected to the well via the “kill line” on the blowout preventer, and by Tuesday morning was siphoning about 12,000 barrels (504,000 gallons) of oil a day, Wells said. About 8,000 barrels (336,000 gallons) a day have been siphoned and burned through the surface rig Q4000.

Those containment efforts will be halted to conduct the integrity test, Wells said.

The possibility of shutting in the well from the top was raised by BP in the past few weeks. The oil company has expressed concern many times about trying to seal the well from the top, citing fears about the condition of the well below the gulf floor. During the “top kill” attempt in May, the well was taking as much mud as engineers were pumping into it. It was not clear whether the mud was leaking into the rock formations or shooting out the cracks and openings in the pipe above the blowout preventer. In a recent interview with The Washington Post, Wells said BP had become increasingly confident that the mud had flowed out the top. He did not elaborate.

During a conference call Monday, BP Chief Operating Officer Doug Suttles was asked why the new sealing cap and the shut-in strategy had not been attempted earlier. He defended the company’s strategy, saying that certain steps could be taken only after engineers had gathered information about the well. A major concern all along was to avoid anything to make the situation worse, he said.

“The problem is, I’ve had to take these steps to learn the things I’ve learned,” he said. “Without taking those steps, it’s unlikely that I would have known what I know now.”


Acesso em: 14/07/2010

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