Abandoned Wells May be a Significant Source of Greenhouse Gases: Methane

Scientists may have uncovered a new and unusual source of greenhouse gases. They've discovered that abandoned wells may contribute substantial amounts of methane to the Earth's atmosphere.

Methane is the unprocessed form of natural gas that contributes to global warming and the greenhouse effect. Pound per pound, methane actually has about 20 times the heat-trapping effect as carbon dioxide. It's produced naturally by processes that include decomposition, and also by human activity, such as landfills and oil and gas production.

While oil and gas companies work to reduce the amount of methane emitted into the air during operations, very little attention has been paid to gas wells that were drilled decades ago and have since been abandoned. That's why researchers decided to investigate to see exactly how much methane was being produced by these old wells.

The scientists placed enclosures called flux chambers over the tops of wells. They also placed flux chambers nearby to measure background emissions from the terrain. This allowed them to estimate exactly how much methane the old wells were emitting.

"The research indicates that this is a source of methane that should not be ignored," said Michael Celia, one of the researchers, in a news release. "We need to determine how significant it is on a wider basis."

In fact, the scientists found that these old wells produced a significant amount of methane. However, only about 15 percent of the wells emitted the gas at a markedly higher level.

"This may be a significant source," said Denise Mauzarall, one of the researchers. "There is no single silver bullet but if it turns out that we can cap or capture the methane coming off these really big emitters, that would make a substantial difference."

The findings are published in the journal Proceedings of the National Academy of Sciences.

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