Searching for anomalous methane in shallow groundwater near shale gas wells

Zhenhui Li, Cheng You, Matthew Gonzales, Anna K. Wendt, Fei Wu, Susan L. Brantley

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Since the 1800s, natural gas has been extracted from wells drilled into conventional reservoirs. Today, gas is also extracted from shale using high-volume hydraulic fracturing (HVHF). These wells sometimes leak methane and must be re-sealed with cement. Some researchers argue that methane concentrations, C, increase in groundwater near shale-gas wells and that “fracked” wells leak more than conventional wells. We developed techniques to mine datasets of groundwater chemistry in Pennsylvania townships where contamination had been reported. Values of C measured in shallow private water wells were discovered to increase with proximity to faults and to conventional, but not shale-gas, wells in the entire area. However, in small subareas, C increased with proximity to some shale-gas wells. Data mining was used to map a few hotspots where C significantly correlates with distance to faults and gas wells. Near the hotspots, 3 out of 132 shale-gas wells (~ 2%) and 4 out of 15 conventional wells (27%) intersect faults at depths where they are reported to be uncased or uncemented. These results demonstrate that even though these data techniques do not establish causation, they can elucidate the controls on natural methane emission along faults and may have implications for gas well construction.

Original languageEnglish (US)
Pages (from-to)23-30
Number of pages8
JournalJournal of Contaminant Hydrology
Volume195
DOIs
StatePublished - Dec 1 2016

Fingerprint

Methane
gas well
Groundwater
methane
groundwater
well
hot spot
Gases
data mining
Water wells
Hydraulic fracturing
shale gas
Shale gas
natural gas
shale
cement
Shale
Data mining
Natural gas
Cements

All Science Journal Classification (ASJC) codes

  • Environmental Chemistry
  • Water Science and Technology

Cite this

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title = "Searching for anomalous methane in shallow groundwater near shale gas wells",
abstract = "Since the 1800s, natural gas has been extracted from wells drilled into conventional reservoirs. Today, gas is also extracted from shale using high-volume hydraulic fracturing (HVHF). These wells sometimes leak methane and must be re-sealed with cement. Some researchers argue that methane concentrations, C, increase in groundwater near shale-gas wells and that “fracked” wells leak more than conventional wells. We developed techniques to mine datasets of groundwater chemistry in Pennsylvania townships where contamination had been reported. Values of C measured in shallow private water wells were discovered to increase with proximity to faults and to conventional, but not shale-gas, wells in the entire area. However, in small subareas, C increased with proximity to some shale-gas wells. Data mining was used to map a few hotspots where C significantly correlates with distance to faults and gas wells. Near the hotspots, 3 out of 132 shale-gas wells (~ 2{\%}) and 4 out of 15 conventional wells (27{\%}) intersect faults at depths where they are reported to be uncased or uncemented. These results demonstrate that even though these data techniques do not establish causation, they can elucidate the controls on natural methane emission along faults and may have implications for gas well construction.",
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Searching for anomalous methane in shallow groundwater near shale gas wells. / Li, Zhenhui; You, Cheng; Gonzales, Matthew; Wendt, Anna K.; Wu, Fei; Brantley, Susan L.

In: Journal of Contaminant Hydrology, Vol. 195, 01.12.2016, p. 23-30.

Research output: Contribution to journalArticle

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