Methane occurrence is associated with sodium-rich valley waters in domestic wells overlying the Marcellus shale in New York State

Kayla M. Christian, Laura K. Lautz, Gregory D. Hoke, Donald I. Siegel, Zunli Lu, John Kessler

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Prior work suggests spatial parameters (e.g., landscape position, distance to nearest gas well) can be used to estimate the amount of dissolved methane in domestic drinking water wells overlying the deep Marcellus Shale. New York (NY) provides an opportunity to investigate methane occurrence prior to expansion of high-volume hydraulic fracturing because unconventional gas production is currently banned in the state. We sampled domestic groundwater wells for methane in 2013 (n = 137) across five counties of NY bordering Pennsylvania, and then resampled a subset of those wells in 2014 for methane concentrations and δ13C-CH4 and δD-CH4. The majority of waters from wells sampled (77%) had low concentrations of methane (<0.1 mg/L), and only 5% (n = 7) had actionable levels of methane (>10 mg/L). Dissolved methane concentrations did not change as a function of proximity to existing vertical gas wells, nor other parameters indicating subsurface planes of weakness (i.e., faults or lineaments). Methane levels were significantly higher in wells closer to hydrography flow lines, and most strongly correlated to Na-HCO3 water type. The distribution of methane between Ca-HCO3 (n = 76) and Na-HCO3 (n = 23) water types significantly differed (p < 0.01), with median methane concentrations of 0.002 and 0.78 mg/L, respectively. Combined classification of sampled waters based on the dominant water cation, well topographic position, and geologic unit of well completion effectively identified wells with a greater than 50% probability of having methane concentrations exceeding 1 mg/L. Such classification schemes may be useful as a screening tool to assess natural versus gas production-related sources of methane in domestic wells.

Original languageEnglish (US)
Pages (from-to)206-226
Number of pages21
JournalWater Resources Research
Volume52
Issue number1
DOIs
StatePublished - Jan 1 2016

Keywords

  • contamination
  • groundwater
  • shale gas

ASJC Scopus subject areas

  • Water Science and Technology

Fingerprint

Dive into the research topics of 'Methane occurrence is associated with sodium-rich valley waters in domestic wells overlying the Marcellus shale in New York State'. Together they form a unique fingerprint.

Cite this