Causes and extent of elevated groundwater methane concentrations in Eastern Kentucky

Abstract

Elevated levels of methane (CH4) in groundwater are a critical environmental issue as they can lead to accumulation of gas in enclosed areas and result in explosive environments. A recent study in northeastern Kentucky identified dissolved methane to be widespread, with 28% (n=51) of analyzed domestic wells in the “warning” and “immediate action” level ranges. In contrast, a study in southeastern Kentucky observed significantly lower concentrations. There is no agreement on the sources of methane, the mechanisms responsible for the concentration differences or how far south the high methane zone extends. Methane is generated and transported by several microbial and anthropogenic processes, and comprehensive baseline geochemical data is necessary to identify its sources and pathways. In recent years, horizontal drilling and hydraulic fracturing have been explored as options to develop two major oil and gas plays in eastern Kentucky, the Devonian Berea Sandstone and the Cambrian Rogersville Shale. This study will sample and analyze ~30 groundwater wells within the ~60-Km region separating the existing groundwater methane studies. Water samples will be analyzed for concentrations of cations, anions and metals to characterize water quality. Isotopic ratios of stable carbon and hydrogen in methane will be used to identify methane sources. Finally, the measurement of the water isotopologues and dissolved organic carbon isotopes will be used to identify different water sources. This study will provide baseline information for water quality and dissolved gases and serve as a reference to prevent and evaluate contamination from resource development in this area.

AAPG Datapages/Search and Discovery Article #90351 © 2019 AAPG Foundation 2019 Grants-in-Aid Projects