Evaluation of Methane Sources in Groundwater in Northeastern Pennsylvania

• Published in: Ground water Vol. 51; no. 3; pp. 333 - 349
• Main Authors: Molofsky, Lisa J., Connor, John A., Wylie, Albert S., Wagner, Tom, Farhat, Shahla K.
• Format: Journal Article
• Language: English
• Published: Malden, US Blackwell Publishing Ltd 01.05.2013; Ground Water Publishing Company
• Subjects: Assessments; Carbon Isotopes; Chemical compounds; Environmental Monitoring; Extraction; Fracture mechanics; Geology; Groundwater; Groundwater - analysis; Groundwater - chemistry; Hydrocarbons; Hydrocarbons - analysis; Hydrology; Isotopes - analysis; Methane; Methane - analysis; Migration; Oil and Gas Fields; Oil shale; Pennsylvania; Research Papers; Topography; Water Quality; Water Supply - analysis; Water Wells; Wells; Pennsylvania
• ISSN: 0017-467X; 1745-6584
• DOI: 10.1111/gwat.12056

Testing of 1701 water wells in northeastern Pennsylvania shows that methane is ubiquitous in groundwater, with higher concentrations observed in valleys vs. upland areas and in association with calcium‐sodium‐bicarbonate, sodium‐bicarbonate, and sodium‐chloride rich waters—indicating that, on a regional scale, methane concentrations are best correlated to topographic and hydrogeologic features, rather than shale‐gas extraction. In addition, our assessment of isotopic and molecular analyses of hydrocarbon gases in the Dimock Township suggest that gases present in local water wells are most consistent with Middle and Upper Devonian gases sampled in the annular spaces of local gas wells, as opposed to Marcellus Production gas. Combined, these findings suggest that the methane concentrations in Susquehanna County water wells can be explained without the migration of Marcellus shale gas through fractures, an observation that has important implications for understanding the nature of risks associated with shale‐gas extraction.