Analysts: Relief Wells May Not Stop Spill Until Christmas

(June 17) -- President Barack Obama promised in his speech Tuesday night that sometime in August, the Gulf oil spill will finally be tamed. The leak will be plugged. The live "spillcam" can be turned off.

August seems like a long way off, especially since the flow rate has been raised (yet again) so that the amount of oil gushing into the gulf is now believed to be 60,000 barrels a day.

And yet, depending on how the company fares in drilling its relief wells, August could come and go with the oil still running.

Dan Pickering, co-president of Tudor, Pickering, Holt & Co., a Houston-based oil and gas investment bank, thinks Christmas is not an unreasonable scenario, as worst-case scenarios go.

"There's a truism that Murphy lives in the oil fields," said Dave Pursell, a partner of Pickering's. "They can run into snags that will push that timeline back: hurricanes, operational miscues, difficulty finding the wellbore. That pushes it to December," Pursell continued. "Of course, the ultimate worst-case scenario is that the relief wells blow out and there's no way to cap it."

Drilling relief wells is widely considered the most dependable method for shutting down runaway wells. Every oilman who has made the cable talk show circuit in the past nine weeks has scoffed at BP's efforts to stanch the oil with the top hat and the junk shot, saying relief wells would do the trick.

"There aren't many options beyond the relief wells. In virtually every case I can think of, they do work," said Dave Rensink, president of the American Association of Petroleum Geologists.

Relief wells provide drillers with a route to the original well so that heavy mud and cement can be inserted to plug the flow of oil. As the relief wells approach the original well, drillers send down high-tech magnetic equipment that will help find the original well casing. The plan, Rensink said, is to intersect with the original well at the deepest possible point, so that the mud pumped into it will form a high, heavy column. Once the mud pushes the oil down, the original well is plugged with cement.

The trouble with relief wells is that they don't always work right away. The chore becomes even more difficult when you're a mile underwater, Rensink said.

"The probability of being able to do it on the first, second or third try -- well, BP would have to be very lucky," he said. "There are so many uncertainties. Christmas? It could happen."

In the blowout of the Ixtoc 1 well off the Yucatan Peninsula in 1979, it took 290 days -- and two relief wells -- to stop the flow of oil. And that well rig was standing in shallow water, just 150 deep. Last year, off the coast of Australia, another well blowout was finally plugged through a relief well. But it took five attempts.

BP began drilling a pair of relief wells 10 days after the Deepwater Horizon blowout. Company spokesman Tristan Vanhegan confirmed those are the only two it plans to use. "We are very confident those will work," he said.

The wells are being drilled through 18,000 feet of rock to intercept an 8-inch pipe in the runaway well. It is painstakingly slow work.

"The deeper you go, the slower the drilling," Rensink said. "You're drilling a few hundred feet a day."

As of today, the first well had reached 14,000 feet and the second had reached 9,120 feet, Vanhegan said.

Rensink discounted speculation that the relief wells could also blow out. Still, there are myriad other complications that occur.

Robert Bea, a University of California at Berkeley engineering professor and member of a panel of experts assembled by Obama to study the blowout, equated plugging the original well with trying to plug holes in a leaking hose.

"That's not an easy thing to do because the reservoir is producing fluids and gases and solids that come up through the wellbore," he said. "You can plug the wellbore and all that could happen is the reservoir looks for the next zone of weakness -- and that's the cement outside the wellbore. We all know that the cement is questionable."