H31E-1456
Dissolved methane occurrences in aquifers in the footprint of Texas shale plays and their controls
Wednesday, 16 December 2015
Poster Hall (Moscone South)
Jean-Philippe Nicot1, Patrick John Mickler1, Toti Larson2, Roxana Darvari3 and Rebecca C. Smyth3, (1)University of Texas at Austin, Austin, TX, United States, (2)University of Texas, Austin, TX, United States, (3)University of Texas at Austin, Bureau of Economic Geology, Jackson School of Geosciences, Austin, TX, United States
Abstract:
Many constituents typically associated with oil and gas production, such as methane and higher-order hydrocarbons, exist naturally in shallow groundwater. Recent studies of aquifers in the footprint of several gas plays across the US have showed that (1) dissolved thermogenic methane may or may not be present in the shallow subsurface and (2) shallow thermogenic methane could be naturally occurring and emplaced through mostly vertical migration over geologic time and is not necessarily a consequence of gas production from a gas play. A total of 800+ water wells have been sampled across the state of Texas to characterize shallow methane in fresh-water aquifers overlying shale plays and other tight formations (Barnett, Eagle Ford, Haynesville shale areas as well as in the Delaware Basin of West Texas). Analytical results suggest that dissolved methane is not widespread in shallow groundwater and that, when present at concentration greater than 10 mg/L, is often of natural but thermogenic or mixed origin according to the isotopic signature and to the presence of other light hydrocarbons.
