Controls on methane occurrences in shallow aquifers overlying the Haynesville Shale gas field, East Texas

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doi: 10.1111/gwat.12500
Authors:Nicot, Jean-Philippe; Larson, Toti; Darvari, Roxana; Mickler, Patrick; Slotten, Michael; Aldridge, Jordan; Uhlman, Kristine; Costley, Ruth
Author Affiliations:Primary:
University of Texas at Austin, Jackson School of Geosciences, Austin, TX, United States
St. Edward's University, United States
Volume Title:Ground Water
Source:Ground Water, 55(4), p.443-454. Publisher: Wiley-Blackwell on behalf of National Ground Water Association, Westerville, OH, United States. ISSN: 0017-467X
Publication Date:2017
Note:In English. 70 refs.; illus., incl. geol. sketch maps
Summary:Understanding the source of dissolved methane in drinking-water aquifers is critical for assessing potential contributions from hydraulic fracturing in shale plays. Shallow groundwater in the Texas portion of the Haynesville Shale area (13,000 km2) was sampled (70 samples) for methane and other dissolved light alkanes. Most samples were derived from the fresh water bearing Wilcox formations and show little methane except in a localized cluster of 12 water wells (17% of total) in a approximately 30 × 30 km2 area in Southern Panola County with dissolved methane concentrations less than 10 mg/L. This zone of elevated methane is spatially associated with the termination of an active fault system affecting the entire sedimentary section, including the Haynesville Shale at a depth more than 3.5 km, and with shallow lignite seams of Lower Wilcox age at a depth of 100 to 230 m. The lignite spatial extension overlaps with the cluster. Gas wetness and methane isotope compositions suggest a mixed microbial and thermogenic origin with contribution from lignite beds and from deep thermogenic reservoirs that produce condensate in most of the cluster area. The pathway for methane from the lignite and deeper reservoirs is then provided by the fault system. Abstract Copyright (2017), , National Ground Water Association.
Subjects:Active faults; Aliphatic hydrocarbons; Alkanes; Aquifer vulnerability; Aquifers; C-13/C-12; Carbon; Clastic rocks; Cluster analysis; Coal; Coal seams; Controls; Faults; Ground water; Haynesville Formation; Hydraulic fracturing; Hydrocarbons; Isotope ratios; Isotopes; Jurassic; Lignite; Mesozoic; Methane; Oil and gas fields; Organic compounds; Provenance; Saturation; Sedimentary rocks; Shale; Shallow aquifers; Solutes; Stable isotopes; Statistical analysis; Upper Jurassic; Water quality; Water wells; East Texas; Panola County Texas; Shelby County Texas; Texas; United States; Wilcox Aquifer
Coordinates:N313500 N322200 W0935000 W0943500
Record ID:2017076550
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom
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