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BP tests begin amid hope that Gulf oil spill is ending

Perhaps for the first time since the Deepwater Horizon exploded on April 20, BP is on the verge of shutting off the source of the Gulf oil spill.

Perhaps for the first time since the Deepwater Horizon exploded on April 20, BP is on the verge of shutting off the source of the Gulf oil spill.

As of Wednesday afternoon, BP got the go-ahead for its integrity tests on the leaking well. If the tests are successful, BP will at last have turned off the spigot to a geyser that has gushed tens of thousands of barrels of oil a day into the Gulf for nearly three months.

The tests could fail and be abandoned at any time during the two-day process. But success, if it comes, will require patience.

Already, the federal government made BP wait a day before starting the integrity test – wanting to make sure that engineers had taken every possible precaution to avoid making things worse. And on Wednesday, the man in charge of relief efforts, retired Coast Guard Adm. Thad Allen, laid out how the same caution that delayed the tests will now animate every step of the tests themselves.

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If they can, BP and the federal government want to avoid reverting to the backup plan – collecting all the oil leaking from the well with ships on the surface. For one, BP won’t be ready to collect all the oil for two weeks – not all the ships needed are on site. Moreover, hurricanes would disrupt any oil collection effort.

So engineers will go slow in hopes of getting it right.

In a series of six-hour intervals, engineers will shut down the five open valves through which oil is flowing. Every step of the way, they will monitor pressure readings that could indicate whether they could be creating new problems.

If the pressure does not continue to rise as they shut down more valves, the effort will likely be abandoned. Low pressure would indicate that oil is finding another way out – perhaps through cracks in the well bore that could ultimately result in new oil gushers erupting through the sea floor.

If the pressure does rise and remains stable, suggesting that the oil is being contained in the well bore, engineers will proceed valve by valve until they get to the final one probably some time tomorrow.

The desire for caution is such that a remote-controlled submarine will shut off the last valve one turn of the knob at a time, pausing after each twist so engineers can look for any changes in pressure data, Allen said.

News reports suggest that at least the first valve – which controls the main flow of oil out of the top of the new cap – has been shut. Of the remaining four valves, two are on the original blowout preventer and two are on the new cap installed this week.

If the integrity tests show that these valves need to be reopened, then ships on the surface will hook up to the valves to siphon the oil.

During the past week, ships have already been collecting oil from the two valves on the blowout preventer. The ships that would connect to the two valves on the cap, however, are still about two weeks away.

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All told, these four ships would be able to collect as many as 80,000 barrels (3.4 million gallons) of oil a day. The flow rate from the well is estimated to be no more than 60,000 barrels a day.