A Duke University study released Monday found high levels of leaked methane in well water collected near shale gas drilling and hydraulic fracturing (fracking) sites in the Marcellus Shale. However, Duke researchers said there was no evidence that fracking fluids contaminated the water wells.
Separately Scotland-based Wood Mackenzie disputed recent findings by Cornell University that the methane emissions during the completion process of fracked wells exceeds that of coal.
Four Duke University scientists collected and analyzed water samples from 68 private groundwater wells across five counties in northeastern Pennsylvania and New York, which overlay the Marcellus Shale play. "We found measurable amounts of methane in 85% of the samples, but levels were 17 times higher on average in wells located within a kilometer of active hydrofracking sites," said Stephen Osborn, post-doctoral research associate at Duke's Nicholas School of Environment. The contamination was observed primarily in Bradford and Susquehanna counties in Pennsylvania.
Meanwhile, the Wood Mackenzie analysis has found that a recent study by Cornell University researchers significantly overestimated the fugitive methane emissions from unconventional natural gas wells.
Cornell researchers said that methane emissions of flowback gas during completion of fracked wells are high enough to increase the greenhouse gas footprint of shale and tight gas to levels that exceed those of coal (see Daily GPI, April 13). The Cornell research was quickly challenged by a study published by the gas industry-supported American Clean Skies Foundation (see Daily GPI, April 21). Now Wood Mackenzie says the Cornell study overestimated the average volume of gas vented during well completion and flowback stages by 60-65% and overestimated the impact from emissions during well completions by up to 90%.
(To read the full story go to shaledaily.com.)
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