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TitleDeep groundwater circulation through gas shales in mountain belts
AuthorGrasby, S E; Ferguson, G; Brady, A; Sharp, C; Dunfield, P; McMechan, M
SourceProcedia Earth and Planetary Science vol. 17, 2017 p. 532-533,
Alt SeriesEarth Sciences Sector, Contribution Series 20160346
Mediapaper; on-line; digital
File formatpdf
ProvinceBritish Columbia
AreaLiard Basin
Subjectsthermal springs; shales; sedimentary basins; sedimentary environment; surface waters; water circulation patterns; groundwater circulation; permeability; gas seeps
ProgramGeothermal Assessments, Energy Geoscience
AbstractThermal spring systems were examined in a mountainous region west of a major gas-shale development that occurs in the equivalent undeformed sedimentary basin. Geochemical data and geothermal modelling indicate that springs originate from circulation of surface water to depths exceeding 3.8 km. This implies that in the deformed belt surface waters actively circulate through gas-prone shales at depth. These circulation systems appear largely controlled by naturally occurring anomalous high permeability pathways that original by unusual tectonic features. Such pathways provide direct connection between deep gas-shale units and the shallow surface environment. This is observed by present day leakage of thermogenic gas and higher hydrocarbons to surface in spring waters. This leakage is partly attenuated by natural occurrence of methanotrophic microbial communities in the spring waters.
Summary(Plain Language Summary, not published)
This extended abstract describes results of a study of a natural deep groundwater system in the mountains of NE BC, showing that deep groundwater circulation occurs through shales that host gas in the Liard Basin. Results imply that any potential development of these shales in the mountain belts needs to account for existing natural fracture systems that connects deep shale units to surface.