The Science Behind Deep-Water Oil Drilling

Efforts to capture oil leaking from the BP well in the Gulf of Mexico suffered a setback Wednesday, after an underwater robot bumped into the venting system of a containment cap -- forcing BP to temporarily remove its latest effort to capture the millions of gallons of oil spewing into the Gulf.

April's Deepwater Horizon disaster has continued to raise questions about the oil industry's ability to manage the challenges and risks involved in drilling miles below the ocean floor to reach highly pressurized oil deposits.

Science reporter Henry Fountain has been covering the environmental disaster for The New York Times. In an interview with Fresh Air's Dave Davies, Fountain explains how deep-water drilling works thousands of feet below sea level and what may have gone wrong on the Deepwater Horizon.

Fountain says he also learned the lengths and extremes to which humans will go to acquire oil.

"One of the things I learned is that this particular well that had the blowout wasn't really unusual. ... But one of the things is, it really goes back to our need for oil, and not just for cars but for pretty much everything -- plastics, fertilizers and society," he says. "And the problem is, is that the easy oil has basically been gotten: the oil from land, the oil from shallow offshore wells. So going forward, we're going to have more of these wells drilled in extreme conditions. So, in a way, there's potential for more disaster in the future, and it seems to me that if there were ever an argument for pursuing alternative energies, the argument is being made now -- in a pretty hard way, but it's being made."

Interview Highlights

On the scale of the deep-water rig

"Most people don't realize how big these rigs are and the huge scale of drilling in general, particularly deep-water drilling. The Deepwater Horizon was something like 300-by-300 feet, with a drilling derrick 220 to 230 feet high and designed to drill in very deep water, up to about 7,000 feet. So it carries thousands of feet of drill pipe, thousands of feet of other piping -- it's really a mammoth piece of equipment."

On how the rig stays in place

"It's called dynamic position. I believe this rig had eight thrusters. They can rotate 360 degrees, and basically it can keep the rig over a certain spot for days at a time."

On the importance of the synthetic mud pumped into the shaft

"You have 5,000 feet of water [in the case of Deepwater Horizon] and you have 13,000 feet of rock, and that puts a lot of pressure on the oil, which is basically in a reservoir down deep. So without the drilling mud to create the heavy column of downward force, the oil and gas would just come up."

On the blowout preventer

"You can think of the blowout preventer as the last line of defense or the second line of defense. And it's huge. The one that the Deepwater Horizon had was like 53 feet tall, about 25 feet wide on both sides like a square, and weighed something like 350 tons, so it's not a light-duty piece of equipment, really. ... It has several different sealing mechanisms on it, and some of them are designed to be used -- not in emergency situations, but if they have to do certain tests, they'll close part of the blowout preventer."

On what happened on the Deepwater Horizon

"There was some sort of well control issue, some sort of big kick of methane. They were sort of struggling with things for half an hour at least to get things under control. There's indications that they diverted flow and tried other methods to try to stop things. Probably operated parts of the blowout preventer and may have tried to trigger the ultimate feature of the blowout preventer, which is the blind-shear rams -- which actually sort of cut the drill pipe and sealed off the well. And that's really a last-ditch thing, because if you do that, your drill pipe falls down the hole and you have to go back and fish it out and it's going to take you a long time and it's going to cost you a lot of money."

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