Gulf oil spill: Why is it so hard to stop?
Working in the deep sea at the source of the Gulf oil spill is a bit like working in space, say scientists. It's a hard place to get to, a tricky space in which to maneuver, and subject to daunting laws of physics.
| Hammond, La.
There's a reason the deep ocean is dubbed "inner space."
It's a place that poses some of the challenges that astronauts and robotics operators face in outer space.
Just getting equipment there, for instance, can turn a 10-hour job into a 100-hour task. Multiton submersibles must perform operations that require brute force or the delicacy of a watchmaker, guided by engineers using an array of cameras that offer little depth perception. One false nudge of a joystick and the vehicle could go sliding by its target.
Yet the spill is shaping up as more than a test of deep-sea technology. It could be the offshore oil industry's version of the Challenger or Columbia space shuttle disasters – tragedies whose triggers had as much to do with attitudes and organizational culture as with hardware or operating conditions.
The blowout, explosion, and fire, which killed 11 workers and sank the Deepwater Horizon rig, betray technological arrogance and short memories, says Thomas Beamish, a sociologist at the University of California at Davis who has written in-depth about a 38-year-long oil spill in the Guadalupe Dunes 170 miles north of Los Angeles.
"We deal with the last catastrophe and move on, and sort of expect it not to happen again," he says.
Indeed, in a recent interview with the Financial Times, Tony Hayward, British Petroleum's chief executive officer, acknowledged that the company considered the blowout a "low probability, high impact event."
"What is undoubtedly true is that we did not have the tools you would want in your tool kit," he said.
Nor did the company have experience applying its various techniques for stemming the flow at such depths. From four-story containment domes to junk shots and top kills, the blowout defied efforts to stanch the thousands of barrels of oil erupting into the Gulf of Mexico each day, though the new containment cap is having some success, capturing nearly 630,000 gallons of oil in the latest 24-hour period. It is unclear what percentage of the leaking oil that is.
Why is it so hard to stop the flow? The reasons are many.
For one, oil in reservoirs under the Gulf of Mexico is subject to very high pressures – as much as 9,000 pounds per square inch, notes Steve Sears, who heads the petroleum engineering department at Louisiana State University in Baton Rouge. This means the spewing oil is more forceful – and harder to handle.
The depth of the blowout – 5,000 feet – makes the effort even more difficult. Robotic space exploration provides "a very good analogy" for deep-sea drilling, Dr. Sears says.
One major challenge is logistics – moving hardware on the surface to the seafloor. That process often involves building a drill pipe first. To do that, rig workers must assemble the pipe one 90-foot section at a time in a stop-start sequence – lowering the assembly another 90 feet into the water with each new segment. To get to the depth of the wellhead they must assemble and carefully lower at least 55 segments.
"It's not that the task is more complicated; it just takes a long time to do it," he says.
At depth, the remotely operated vehicles (ROVs) take over.
They weigh anywhere from 1,000 pounds to five tons and have two arms. One is capable of coarse movements and is used to grasp claw-holds on undersea hardware. The other is capable of the full range of movement of a human arm and can grip with either a light touch or something more viselike as the situation demands.
A heavily armored cable lowers the craft close to its working area. The craft then moves out of a protective cage but remains linked to the surface through another 300 to 500 feet of softer umbilical cable.
An ROV may have from two to four video cameras to help the pilot guide the vehicle. But it's up to the pilot to mentally convert the two-dimensional images on the screen into three dimensions to estimate how far an object is from the ROV, says Knute Brekke, who spent 11 years as a diver and ROV pilot working on oil rigs in the Gulf before moving to the Monterey Bay Aquarium Research Institute in California.
If an operator moves a vehicle too close to the bottom, the ROV's thrusters stir up sediment, which cuts visibility. If an operator loses track of where the ROV's umbilical is, the cable can become tangled. Often, two or three ROVs are operating at once, demanding intense focus.
Movements typically are slow and deliberate, just as those of astronauts during spacewalks. The ROVs are neutrally buoyant; left to their own devices, they hover. If an operator accelerates the ROV too quickly, the craft's mass will ensure it keeps moving long after the thrusters stop. The operators also have to compensate for sea currents and – at the Deepwater Horizon site – navigate around wreckage.
While not a perfect analogy, operating an ROV is a bit like playing a computer game with a partner, says Mr. Brekke. The pilot runs the ROV, while the copilot operates the arms.
The difference? "If you see 'game over' you start looking for another job," he says.
Yet even with such sophisticated tools, the Deepwater Horizon blowout has highlighted a lack of readiness. Dr. Beamish notes that 15 years ago, to drill off Santa Barbara, Calif., "You had to have a fire crew ready in harbor, you had to have booms ready, you had to have a whole infrastructure at ready."
These days, he says, that should include boats equipped to deliver fire suppressants, rather than boats pumping seawater on an oil-fueled fire hot enough to soften steel. In addition, the culture within an organization must lay a human foundation for response.
"The big one that is coming out of this one is fatigue," says Karlene Roberts, a professor emeritus at the University of California at Berkeley who researches organizations whose mistakes lead to major catastrophes.
"It could be that there isn't a mandatory law that takes [workers] off the job after so many hours," she says.
As with the Challenger and Columbia disasters, she adds, such factors should be probed just as deeply as technological failures.
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