Tuesday, May 10, 2011

Hydraulic fracturing

Drilling Is Tied to Gas in Eastern Well Water

Natural-gas drilling appears to be allowing potentially explosive methane gas to seep into some drinking-water wells in Pennsylvania and New York, according to a study by scientists from Duke University.

The Duke researchers tested 60 private water wells in Pennsylvania and New York, and found that those near gas wells had methane levels that were 17 times as high as those in non-drilling areas. While not considered a toxin, methane bubbling out of the water can build up and cause fires or explosions.

The researchers didn't find any evidence that chemicals used in the drilling process were leeching into water supplies, as some environmentalists and other critics of the drilling have contended.

The natural-gas industry immediately took issue with the size and methodology of the study, which is one of the first independent investigations into the effects of gas extraction on drinking water, and is sure to fuel the growing controversy over drilling for gas.
Much of that controversy has focused on hydraulic fracturing, the practice of injecting millions of gallons of water, sand and chemicals into the ground to break up gas-bearing rocks. The technique has allowed companies to tap vast new gas reserves across the nation.
The natural-gas industry says that fracturing is safe, and that properly drilled wells don't leak either gas or chemicals. Environmentalists and industry groups have produced dueling studies assessing the risks of drilling on water supplies.

"There are a lot of anecdotes and a lot of un-peer-reviewed white papers, but very little hard research," said Robert B. Jackson, a Duke professor of biology and one of the study's authors.
The study, which will be published this week in the journal Proceedings of the National Academy of Sciences, tested drinking-water wells that sit atop a huge gas-bearing rock formation called the Marcellus Shale.
Twenty-six of the wells in the study lie within one kilometer of an active gas well; the others are farther from drilling activity. Wells in both categories showed signs of methane, but the levels were far higher in wells closer to drilling sites.
The natural-gas industry disputed the study's findings, saying that it didn't examine enough wells and didn't have data about water quality before drilling began. "To suggest this study is conclusive I think is a bit much," said Patrick Creighton, a spokesman for the industry group Energy in Depth.

Methane itself isn't toxic and isn't regulated under federal drinking-water standards. But methane in water can bubble into the atmosphere, where it can explode, especially if the gas gets trapped in a confined area such as a shower or washing machine. Nine of the wells tested in the study had gas concentrations above the level that the Department of Interior says requires "immediate action."

Methane can seep into aquifers on its own from shallow gas reservoirs, and the industry has suggested that many well-publicized cases of water contamination are naturally occurring. But the Duke team said the gas they found in drilling-heavy areas chemically matched Marcellus gas, not shallow gas that might have seeped in without drilling.
Write to Ben Casselman at ben.casselman@wsj.com

Making it happen
What is hydraulic fracturing? (Courtesy/U.S. Environmental Protection Agency, Independent Petroleum  Association of Mountain States)

Kliphnote: I'm for hydraulic fracturing, only if it's proven safe

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