British Petroleum Oil leak stopped for first time since April

story by Washington Post
written by Joel Achenbach and William Branigin

BP said Thursday that it has stopped oil from leaking out of its blown-out well in the Gulf of Mexico. The gusher has been throttled for the first time since the April 20 blowout on the drilling rig Deepwater Horizon.

Kent Wells, BP's senior vice president of exploration and production, told reporters that a new capping mechanism shut off the flow of crude from the Macondo well at 3:25 p.m. EDT. He made the announcement after engineers gradually shut off valves to test the pressure. The engineers are monitoring the pressure to see whether the new cap and the well bore hold.

BP began the pressure test Thursday afternoon on the blown-out well, ending two days of delays, one caused by government fears that the test could backfire and the other by a leak discovered in part of the well's new cap.

"Although it cannot be assured, it is expected that no oil will be released to the ocean during the test," BP said in a guarded statement announcing the start of the procedure. "Even if no oil is released during the test, this will not be an indication that oil and gas flow from the wellbore has been permanently stopped."

Engineers initiated the test by gradually closing a valve on a new choke line -- one of three ways for oil to leave the newly installed "capping stack" -- so that they can obtain pressure readings from the oil well below the sea floor.

The pressure test, anticipated to last up to 48 hours, is designed to indicate whether the well bore is intact. If it's not, oil and gas could surge into the geological formations and possibly form new leaks from the floor of the gulf. Officials hope that, as the final valve is closed, gauges will show a steady rise in pressure.

This, in turn, could allow engineers to "shut in" the well permanently.

The choke line, part of the new cap on the well, sprang its own leak Wednesday night, and engineers had to work through the night and early morning to pull it off the cap and replace it with a spare waiting on a surface ship. For hours Wednesday night and Thursday morning, video streams from the sea floor showed a chaotic plume of oil and gas continuing to surge from one of the outlets on the 75-ton cap installed earlier this week.

The plumbing trouble showed once again that nothing has come easy in the long campaign to kill the Macondo well, which blew out April 20 and destroyed the Deepwater Horizon rig, killing 11 workers.

Federal officials green-lighted the "integrity tests" after a 24-hour delay, during which government scientists and outside experts demanded more information from BP about possible hazards posed by stopping the flow of the well. They are concerned that a spike in pressure as the flow is clamped could blow oil and gas out of the casing of the well and into the geological formations. Throughout the crisis, engineers have feared the possibility that efforts to fix the problem could make it worse.

Such concerns ultimately did not dissuade authorities from going forward with what could be a high-reward maneuver. Retired Coast Guard Adm. Thad W. Allen, the national incident commander, said Wednesday that, notwithstanding the concerns of scientists, he is "gung ho" about the test.
"It will be terrific news if we can shut in the well," Allen said, adding, however, "I don't want to get anyone's hopes up."

Once BP engineers closed the main chimney on the new capping stack installed atop the well Monday night, that left oil and gas surging from two other ports. The protocol developed by BP and approved by federal authorities called for quickly closing one, known as the kill line, then very gradually reducing the flow from the choke line until the well flows no more.

Federal officials and BP engineers are anxiously observing what happens to pressures in the well. A steady increase in pressure as the flow is reduced would be a strong sign that the Macondo well, drilled by the now-sunken rig Deepwater Horizon, is physically intact, and that oil and gas are not leaking into the surrounding mud and rock formations below the gulf floor.

Robotic submersibles are scrutinizing the muddy gulf floor and the base of the blowout preventer for signs of oil or gas rising from below. Scientists are also using seismic and sonar instruments to monitor any possible movement of hydrocarbons in the rock formations surrounding the well.

If the well can handle the high pressures, BP could leave the well shut in, and it would not further pollute the gulf.

White House press secretary Robert Gibbs discussed the hazards of the test Wednesday.

"If the structural integrity of the well bore isn't strong, what you'll get is oil . . . coming out into the strata," he said. That could mean leaks "from multiple points on the seafloor."

If the pressure readings are too low, BP will abandon the test. The well will be reopened and gush anew. BP would then resume trying to capture as much leaking oil as possible, using lines to surface ships and a new "top hat" on the gusher, while continuing to drill a relief well that could kill Macondo with mud and cement.

With the test imminent, BP paused Wednesday in its effort to drill the first relief well, which is only four feet away, laterally, from the Macondo well. The decision to halt work on the relief well was a precautionary move to ensure that hydrocarbons don't surge into the new hole from the Macondo well during the integrity test, BP Senior Vice President Kent Wells said Wednesday. Work on the relief well will resume when the test ends, he said. The drilling of a second relief well had already been suspended, pending results of the first relief well.

The final run-up to the integrity test highlighted the awkward relationship between BP and the federal government. The government has authority for all major decisions in the spill response, but BP has the technological expertise for the deep-water engineering. BP had planned to proceed with the test Tuesday, but federal scientists called time out, asking for more assurances that the oil company had thought through what might go wrong.

The decision to postpone the test for 24 hours was made Tuesday afternoon, but that decision was not announced until Allen and BP put out news releases late Tuesday -- 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 to clog the well with heavy drilling mud.

Allen said Wednesday that during the top kill, the well pressure never surpassed 6,000 pounds per square inch of pressure. That befuddled engineers, who did not know where the mud, furiously pumped into the blowout preventer from surface ships, was going. They wondered if it was flowing through breaches in the well casing into the geological formation. The other possibility was far more benign: All the mud may have spewed out the top of the well through cracks and openings in the collapsed riser pipe.

"We've never been comfortable with what the 6,000 psi meant during the top kill," Allen said.

He has said that, if all goes right, the pressure in the well during the integrity test will rise to about 8,000 or 9,000 pounds per square inch and stay there.