* Methane found in water wells in the Denver-Julesburg basin, Colorado, is mostly microbially generated in shallow coal seams. About 0.06 to 0.15 percent of wells leaked thermogenic methane due to inadequate surface casing, casing leaks or wellhead-seal leaks ([http://www.pnas.org/content/early/2016/07/05/1523267113.full.pdf Owen Sherwood and others, 2016]). | * Methane found in water wells in the Denver-Julesburg basin, Colorado, is mostly microbially generated in shallow coal seams. About 0.06 to 0.15 percent of wells leaked thermogenic methane due to inadequate surface casing, casing leaks or wellhead-seal leaks ([http://www.pnas.org/content/early/2016/07/05/1523267113.full.pdf Owen Sherwood and others, 2016]). |