Methane occurrence and origin in Dutch groundwater: from shallow aquifers to deep reservoirs

Methane is a common constituent of groundwater with multiple possible origins. Elevated methane concentrations may also result from anthropogenically induced pathways between the deep and shallow subsurface caused by oil and gas production. A baseline characterisation of methane occurrence and origi...

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Main Authors: Gilian Schout, Jasper Griffioen, Niels Hartog, Hans G.M. Eggenkamp, Dirk Gijsbert Cirkel
Format: Article
Language:English
Published: Cambridge University Press 2024-01-01
Series:Netherlands Journal of Geosciences
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Online Access:https://www.cambridge.org/core/product/identifier/S0016774624000209/type/journal_article
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author Gilian Schout
Jasper Griffioen
Niels Hartog
Hans G.M. Eggenkamp
Dirk Gijsbert Cirkel
author_facet Gilian Schout
Jasper Griffioen
Niels Hartog
Hans G.M. Eggenkamp
Dirk Gijsbert Cirkel
author_sort Gilian Schout
collection DOAJ
description Methane is a common constituent of groundwater with multiple possible origins. Elevated methane concentrations may also result from anthropogenically induced pathways between the deep and shallow subsurface caused by oil and gas production. A baseline characterisation of methane occurrence and origin in the subsurface of the Netherlands was made using a large set of methane concentrations in shallow groundwater (n = 12,219, up to 500 mbgs). Additionally, targeted sampling (n = 40) was carried out in (1) the shallow aquifers at locations where the presence of thermogenic methane was deemed most probable, such as above faults and known gas reservoirs, (2) deep groundwater aquifers below the depth of Neogene and Paleogene marine clays that form the hydrogeological base in the country and (3) geothermal formation waters at 1640–2625 mbgs. Median methane concentrations in shallow aquifers are relatively high from an international perspective (0.2 mg L−1). The highest methane concentrations (up to 120 mg L−1) are attributed to reactive organic matter in Holocene deposits and Pleistocene marine and glacial formations. However, elevated concentrations are also found at greater depth (100–160 m bgs) in Pleistocene aquifers in the eastern and southern inland areas of the Netherlands. Isotopic evidence and gas composition of naturally occurring methane indicate that methane in the targeted samples from shallow aquifers was of biogenic origin, and that methanogenesis predominantly occurs via CO2 reduction. Only trace amounts of methane (<0.2 mg L−1) were observed in the deep groundwater aquifers. A combination of methane and ethane isotopic composition showed that this methane consists of varying fractions of both biogenic and thermogenic origin. Methane in the geothermal reservoirs has an oil associated thermogenic origin. Overall, these findings highlight that future observations of thermogenic methane in Dutch shallow groundwater (post-Paleogene) are most probably linked to anthropogenically induced connections with the deep subsurface.
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spelling doaj-art-15d930c7133a40edbeb05a2ca31ea2cf2024-11-15T02:50:44ZengCambridge University PressNetherlands Journal of Geosciences0016-77461573-97082024-01-0110310.1017/njg.2024.20Methane occurrence and origin in Dutch groundwater: from shallow aquifers to deep reservoirsGilian Schout0https://orcid.org/0000-0002-9066-1499Jasper Griffioen1Niels Hartog2Hans G.M. Eggenkamp3Dirk Gijsbert Cirkel4KWR Water Research Institute, Nieuwegein, the NetherlandsCopernicus Institute of Sustainable Development, Utrecht University, Utrecht, the Netherlands TNO Geological Survey of the Netherlands, Utrecht, the NetherlandsKWR Water Research Institute, Nieuwegein, the Netherlands Earth Sciences Department, Utrecht University, Utrecht, the NetherlandsÉquipe de Géochimie des Isotopes Stables, Institut de Physique du Globe de Paris, Université de Paris, Paris, France ISOLAB BV, Geffen, The NetherlandsKWR Water Research Institute, Nieuwegein, the NetherlandsMethane is a common constituent of groundwater with multiple possible origins. Elevated methane concentrations may also result from anthropogenically induced pathways between the deep and shallow subsurface caused by oil and gas production. A baseline characterisation of methane occurrence and origin in the subsurface of the Netherlands was made using a large set of methane concentrations in shallow groundwater (n = 12,219, up to 500 mbgs). Additionally, targeted sampling (n = 40) was carried out in (1) the shallow aquifers at locations where the presence of thermogenic methane was deemed most probable, such as above faults and known gas reservoirs, (2) deep groundwater aquifers below the depth of Neogene and Paleogene marine clays that form the hydrogeological base in the country and (3) geothermal formation waters at 1640–2625 mbgs. Median methane concentrations in shallow aquifers are relatively high from an international perspective (0.2 mg L−1). The highest methane concentrations (up to 120 mg L−1) are attributed to reactive organic matter in Holocene deposits and Pleistocene marine and glacial formations. However, elevated concentrations are also found at greater depth (100–160 m bgs) in Pleistocene aquifers in the eastern and southern inland areas of the Netherlands. Isotopic evidence and gas composition of naturally occurring methane indicate that methane in the targeted samples from shallow aquifers was of biogenic origin, and that methanogenesis predominantly occurs via CO2 reduction. Only trace amounts of methane (<0.2 mg L−1) were observed in the deep groundwater aquifers. A combination of methane and ethane isotopic composition showed that this methane consists of varying fractions of both biogenic and thermogenic origin. Methane in the geothermal reservoirs has an oil associated thermogenic origin. Overall, these findings highlight that future observations of thermogenic methane in Dutch shallow groundwater (post-Paleogene) are most probably linked to anthropogenically induced connections with the deep subsurface.https://www.cambridge.org/core/product/identifier/S0016774624000209/type/journal_articleGroundwater methanemethane isotopesdeep groundwatergas migrationstable chloride isotopeswell integrity failure
spellingShingle Gilian Schout
Jasper Griffioen
Niels Hartog
Hans G.M. Eggenkamp
Dirk Gijsbert Cirkel
Methane occurrence and origin in Dutch groundwater: from shallow aquifers to deep reservoirs
Netherlands Journal of Geosciences
Groundwater methane
methane isotopes
deep groundwater
gas migration
stable chloride isotopes
well integrity failure
title Methane occurrence and origin in Dutch groundwater: from shallow aquifers to deep reservoirs
title_full Methane occurrence and origin in Dutch groundwater: from shallow aquifers to deep reservoirs
title_fullStr Methane occurrence and origin in Dutch groundwater: from shallow aquifers to deep reservoirs
title_full_unstemmed Methane occurrence and origin in Dutch groundwater: from shallow aquifers to deep reservoirs
title_short Methane occurrence and origin in Dutch groundwater: from shallow aquifers to deep reservoirs
title_sort methane occurrence and origin in dutch groundwater from shallow aquifers to deep reservoirs
topic Groundwater methane
methane isotopes
deep groundwater
gas migration
stable chloride isotopes
well integrity failure
url https://www.cambridge.org/core/product/identifier/S0016774624000209/type/journal_article
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AT nielshartog methaneoccurrenceandoriginindutchgroundwaterfromshallowaquiferstodeepreservoirs
AT hansgmeggenkamp methaneoccurrenceandoriginindutchgroundwaterfromshallowaquiferstodeepreservoirs
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