New Equipment Heads to Battle Spill
Oil executives, state and federal officials and especially residents want the oil spilling into Gulf Coast waters to stop - but it hasn't.
And the question remains why the available technology and preventive measures haven't worked.
"We will stop the leaks, but it's not like the technology is just lying around," says National Academy of Engineering member Kenneth Arnold of K Arnold Consulting of Houston, an oil industry consulting firm. "It has to be built."
In fact, a newly built 100-ton steel-and-concrete box headed out to sea Wednesday in the latest attempt to bring the oil leak under control.
Since the Deepwater Horizon oil rig exploded April 20, more than 200,000 gallons of oil a day have leaked from its 4,992-foot-deep wellhead, and there have been at least three related pipe ruptures. Energy company BP has stopped one of the leaks, and the latest hope, the concrete container, should be deployed today once it arrives over the leaking wellhead aboard a drilling ship.
In a 2009 Interior Department plan, BP, which leased the rig, suggested it had "the capability to respond" to an "uncontrolled blowout" of 300,000 gallons a day. However, an automatic blowout preventer, a set of valves and cutoffs sitting atop the wellhead on the seafloor, failed to automatically fire on the day of the accident, according to BP Chief Executive Tony Hayward.
"There will be an investigation, and it will likely show a combination of mechanical and human failure," says oil rig engineer Robert Bea of the University of California-Berkeley. "At the bottom, somebody made a bad decision" about the design, maintenance or operation of the well.
During drilling of the well, successively narrower-mouthed strings of pipe were lowered into the ground and cemented into place.
Until the last pipe could be sealed with a final cement cap, drilling "mud," an engineered high-viscosity fluid, filled the hole, and its weight trapped the oil in the reservoir from release.
In the blowout, the pressure from gas trapped in the underground oil layer about 18,000 feet down must have overcome the weight of the drilling mud, Bea says, blasting free an opening.
Experts pointed to three ways to battle the oil leak:
- Remotely piloted subs could trigger the intact blowout preventer. In theory, this solution could shut off the oil immediately if the robots reach and activate the appropriate hydraulic valves, but attempts have met with no success, perhaps because of debris or blasted-out pipe (which may have retracted like a telescoping antenna) locking the well open.
- Subsea containers such as the new containment box could cap the wellhead. Such a container could stop 90 percent-95 percent of a leak, Arnold says, if blowout debris doesn't prevent it from settling over the leak.
- A relief well could intersect the well hole and stop it up with cement, an effort in the offing. That should work but could take up to three months, Hayward says.
"Three months is about right for a relief well at this depth," Bea says.
He warns that blowouts are becoming more common as rigs drill deeper and deeper off the continental shelf.
The Santa Barbara, Calif., blowout in 1969, which sparked the creation of Earth Day, emerged from a reservoir 3,500 feet deep 6 miles off the California coast. The current spill springs from about 18,000 feet deep, about 50 miles from the Louisiana coast.
"The drilling technology is fantastic and high-quality, a lot of time and money is spent on getting it right, but it appears we are pushing things past the point of safety," Bea says.
Norway and Brazil require floating rigs to be equipped with a sound-triggered switch to activate blowout preventers, something absent from the Deepwater Horizon wellhead. Bea suggested such a switch might have helped.
Arnold says the acoustic devices have drawbacks and might not have made any difference, given the failure of the valves to close despite "dead-man" switches that should have fired in the first moments of the disaster, as drilling mud started backing out of the well.
Some evidence suggests that moments before the disaster April 20, BP tested the blowout preventers, Arnold says, perhaps taking some monitoring equipment offline.
That could have prevented workers from noticing gas rising up the well, which may have contributed to the accident.