How to stop the oil leak in Louisiana

by Alan Boyle

BP is trying three strategies to stem the flow of crude oil from a wrecked drilling site about a mile beneath the surface of the Gulf of Mexico. But none of the strategies is a slam-dunk. Depending on what works, it could take days or months to plug the leaks that are causing what's shaping up as a catastrophic oil spill.

Meanwhile, the Deepwater Horizon site is continuing to leak an estimated 200,000 gallons (5,000 barrels) of oil daily from three breaks in the ruined line. Every day, millions of dollars are being added to the leak's cost. Experts are using a variety of measures to cope with that flow: Chemical dispersants are being released underwater, close to the breaks, and more than 300,000 feet worth of floating booms have been deployed to contain the surface slick.

Plan A: Robotic surgery

Trying to contain the oil being spilled is hard enough. But eventually the spill will have to be stopped if there's to be any hope of stabilizing the situation. That was supposed to be the job of the blowout preventer, a stack of valves and tanks that should have closed off the wellhead when the Deepwater Horizon oil rig exploded and sank on April 20.

The blowout preventer, also known as a BOP, should have slammed the pipe shut when the pressure went out of control. The BOP could have been activated by the crew on the oil rig. Eleven members of the crew were killed in the explosion - but even if they couldn't trigger the shutoff, there was a "dead-man's switch" that should have come into play. (Yet another backup triggering mechanism, which uses acoustic signals to trigger the switch remotely, was not installed on this rig.)

BP officials say they were baffled by the BOP's failure. "What has failed here is the ultimate safety device on a drilling rig," Tony Hayward, chief executive officer for the BP Group, told NBC's "TODAY" show.

For days, the company has been sending remote-controlled submarines down to the site in an effort to close the BOP's shutoff valves with their robotic arms. "This is like doing open-heart surgery at 5,000 feet in the dark," Lamar McKay, BP America's chairman and president, told ABC News over the weekend.

BP's chief operating officer, Doug Suttles, said the robotic surgery has been unsuccessful. The valves "probably have closed," but it looks as if the device's sealing elements "did not seal," he told reporters at a briefing today.

Earlier today, BP spokeswoman Sheila Williams told me that the robots have not been able to close the valves any further. All this suggests that the blowout preventer is out of commission - perhaps because of damage done during the oil rig's collapse.

Plan B: Put a lid on it

Putting a lid on the leaks appears to be the most promising medium-term strategy. Workers from Louisiana-based Wild Well Control are currently slaving over a 125-ton, 40-foot-high chamber that would be set on top of the largest leak source, toward the end of the bent-up pipeline now lying on the sea floor.

Oil flowing into this chamber would be collected and brought up through a new 5,000-foot pipeline to a ship floating on the surface, the Deepwater Enterprise. The oil would be separated from seawater and gas, and then offloaded to an onshore oil terminal. As explained in this fact sheet, the Deepwater Enterprise can process 15,000 barrels of oil a day and store as much as 139,000 barrels. The system could collect as much as 85 percent of the oil rising from the seafloor.

The chamber is actually a converted coffer dam that was used after Hurricane Katrina to facilitate the repair of shallow-water wellheads. This first containment structure could be ready to put down from the Deepwater Enterprise in a week or so, and a second structure would be built for Leak No. 2. As for Leak No. 3, the smallest of the breaks, BP plans to use a robo-sub to install a shutoff valve on the pipe as early as today.

Doing all this may sound simple, but the containment strategy has never been used in a deep-water situation before. Ocean currents and oil-rig wreckage will complicate the coming effort to place the chambers precisely over the leaks, and it remains to be seen whether the structures will collect the leaking oil the way BP hopes they will.

Plan C: Plug it up

If Plan B works, that should drastically reduce the flow of additional oil into the area of surface spillage. But it's not a long-term fix. Another oil rig is just beginning to drill a fresh relief well that will angle its way toward the oil-bearing fissure originally tapped by the leaking well. If the relief well hits the fissure in just the right place, mud and concrete will be pumped down to block the leak. This report goes into the process in detail.

It could take two or three months to get the relief well working, BP's Doug Suttles said today. And it's not certain that everything will work the first time. Over the weekend, The New York Times reported on a similar operation in Australia that required five drilling attempts and 10 weeks of work.

However long it takes, Plan C appears to be the only way to bring an end to the Deepwater Horizon oil flow. "In the long run, the relief well is the final solution," said Adm. Thad Allen, commandant of the U.S. Coast Guard.

But it's unlikely that all the problems created by the oil spill will be solved by that time. Dealing with the environmental fallout may well take months or years longer. What do you think? Feel free to weigh in with your comments below.