How to stop the BP oil spill: What else can be tried now?
BP has failed to manually shut the blowout preventer, and it could take three months to drill a relief well. Before then, BP will try to put a giant hood over the leaking wellhead, or perhaps even install a second preventer. But no short-term options have a proven track record to stop an oil spill.
As oil from an offshore drilling blowout spreads across the northern Gulf of Mexico, engineers are scrambling to staunch the flow of crude with everything from deep-sea submersibles to a little-tested approach for capturing the oil in a special structure hovering just above the well head, then pumping the crude into waiting ships or barges.Skip to next paragraph
In Pictures Louisiana oil spill
Subscribe Today to the Monitor
The need for a menu of approaches illustrates the challenges to capping a blow out some 5,000 feet below the sea surface.
"There is a silver bullet; it's drilling relief wells," says Jerome Milgram, an ocean engineering professor at the Massachusetts Institute of Technology in Cambridge, Mass., who has extensively studied ocean-rig blowouts and their effects.
But, he adds, "that takes time" – and time is a commodity in short supply as engineers grapple with ways to corral the crude and remove as much as possible before it can join the quickly spreading slick at the surface.
The Deepwater Horizon oil rig, destroyed April 20 in an explosion and fire that killed 11 workers, is spewing some 200,000 gallons of oil a day on the sea floor.
Regardless of how well current efforts to stem the flow go, relief wells likely will be required, says Dr. Milgram.
Earlier today, the chief executive officer for British Petroleum, Anthony Hayward, noted in an interview with National Public Radio that work on relief wells began May 2. In the meantime, crews have deployed eight remotely piloted submersibles to try to use their claws to "manually" shut valves on a device at the wellhead, known as a blowout preventer. All the systems designed to automatically trigger the blowout preventer failed during the initial event.
Hope in a huge range hood
Beyond that, Mr. Hayward explained that, by the weekend, technicians should be ready to lower a containment structure over the well head designed to capture the oil and pump it to the surface.
That approach has been used once before – in 1979 during a blowout involving the Ixtoc exploration rig in the Bay of Campeche off Mexico. It was the first attempt at using the technique, and it didn't work, says Milgram, who was at the site conducting research on the operation at the time.
Many of the reasons stemmed from engineers attempting something that hadn't been done before – in that case, lowering what he calls a steel sombrero over the wellhead, which was spewing oil and natural gas.
A pipe running from the peak of the sombrero to the surface carried the mix of oil, gas, and sea water into a separation tank on a barge. The device needed no pumps; the gas did all of the pushing as it gathered under the peak, Milgram says.