© Chang W. Lee/The New York TimesRoyal Dutch Shell's Mars platform operates in 2,940 feet of water in the Gulf of Mexico.
Each time BP has tried to cap its runaway well, the company has warned that no one has ever tried it at such a depth.
But elsewhere in the Gulf, companies have been drilling in far deeper water - and making the same environmental and safety promises that BP made.
The BP disaster is calling attention to unique engineering challenges and environmental risks associated with seeking oil and gas at great depths. Equipment designed to withstand harsh conditions deep underwater failed, making some engineers discount assurances that crises could be addressed at far greater depths.
At the same time, the blowout has done much more harm to the Gulf ecosystem than a shallower leak would have caused.
Many of the deepest Gulf wells are near the continent's northernmost coral reefs, treasuries of marine life.
As BP's plan vowed, other deepwater exploration and production plans say a blowout is so unlikely as to merit little or no discussion and no special review. If a blowout occurred even at 10,000 feet, company plans assert, readily available technology would stop the flow of oil and gas quickly, with minor environmental damage.
Operating at an extreme depth is an engineering challenge, largely because of water pressure. Recent research shows that depth also alters how the Gulf's biological systems respond to a rush of oil and gas.
Some experts say worries over depth are misplaced.
Dr. Robert Randall, a professor of ocean and civil engineering at Texas A&M University who works with the industry and federal regulators, said stopping an extremely deep blowout would not be any harder than halting a shallower one because both require the same techniques.
"To me, yes, those capabilities are at hand," Randall said. Offshore drilling industry executives agree.
But to Dr. Bob Bea, a former Shell executive who is now an engineering professor at the University of California, Berkeley, stopping a blowout at 10,000 feet is just a fantasy because of the brutal conditions imposed by pressure, temperature and inaccessibility.
It would be "much more difficult," Bea wrote in an e-mail. "The difficulty is an exponential function of the depth of the water.
"Same as the difference between going to the Moon and going to Mars."
When Kerr-McGee drilled the first well from a fixed platform in federal waters off the coast of Louisiana in 1947, a worker with a snorkel probably could have handled most repairs. It was just 16 feet to the bottom.
Since then, diminishing returns from shallow drilling, plus the development of technology, have pushed the search for oil into previously unimaginable depths.
In 2004, Transocean's Discover Deep Seas rig drilled a well at 10,011 feet about 200 miles south of New Orleans. Other Gulf wells have come in at similar depths.
Temperature is one factor that depends on depth. Water at BP's blowout site is near freezing. Methane hydrates, a mixture of frozen water and methane, or natural gas, scuttled an early attempt to put a containment dome over the well.
Pressure is another factor. Since 5,000 feet is far deeper than divers can go, work is done only by remote-operated vehicles designed to withstand nearly 2,237 pounds of pressure per square inch.
That's about 152 times greater than at the surface. At 10,000 feet, the numbers all double.
When things have gone correctly, such depths have been no impediment to drilling. Deep water, defined as 1,000 feet or deeper, yielded 70 percent of the Gulf of Mexico's oil and 36 percent of its natural gas in 2007, said the American Petroleum Institute, the industry's main U.S. trade group.
The industry has done the research to drill safely at extreme depths, said Brad Beitler, vice president for technology of FMC Technologies, a Houston-based oil and gas equipment and services firm.
"It's a very structured process, as you design equipment, to look at what possibly could happen," he said. "You basically get a bunch of experts around a table and you pick out the worst case. ... We go through quite a sophisticated analysis of these systems."
Handling a blowout at such depths, however, has proved to be different.
BP memos released by Congress show that the well's blowout preventer, a massive device meant as the last-ditch safeguard against a spill, had a leaking hydraulic system before the blowout. It isn't known yet if the cold and pressure of extreme depth caused the leak, or if fail-safe equipment meant for even greater depths might have similar problems.
Just as depth may have contributed to the blowout and has confounded efforts to stop it, depth also has worsened the environmental damage.
Until now, however, the Gulf ecosystem has received little attention in the push to drill in deeper waters, marine biologists say.
"No one thought about what that means ecologically," said Dr. Larry McKinney, director of the Harte Research Institute for Gulf of Mexico Studies at Texas A&M-Corpus Christi.
The discovery of huge, submerged masses of oil, gas and chemical dispersant from the BP blowout is raising troubling new questions.
"What do you do when you have a cloud of this stuff that's the area of the city of San Francisco and 600 feet thick?" McKinney asked. "And that's just one of the smaller clouds, perhaps, that's out there."
McKinney served on a federal advisory committee on ultra-deep-water oil and gas development in 2007-08. He said he felt pretty lonely on a panel dominated by the petroleum industry. When he submitted a memo on the need to incorporate deep-water ecology into federally funded research, it went nowhere.
"They had this huge pressure on them to develop domestic oil and gas resources to get away from the foreign (sources), and of course the Gulf of Mexico was where it was," McKinney said. "I gave my little report, and it didn't go in."
McKinney is worried that "floating dead zones" with drastically low oxygen levels will wash over coral reefs in the northern Gulf. Some research now suggests that those corals are the originals, the sources of the world's corals in shallower water - the tropical rain forests of the sea.
"Those things are like forests of corals," McKinney said. "It's just an incredibly diverse community.
"If you kill all those, what's the recovery time? Hundreds of years."
Source: The Dallas Morning News
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