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TitleTracing the subsurface sulfur cycle using isotopic and elemental fingerprinting: from the micro to the macro scale
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LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorKingston, A WORCID logo; Ardakani, O HORCID logo; Stern, R A
SourceHydrogen sulfide (H2S) in the Montney Formation, Western Canada Sedimentary Basin (WCSB) - investigating a complex issue, workshop proceeding; by Ardakani, O HORCID logo (ed.); Pedersen, P KORCID logo (ed.); Geological Survey of Canada, Open File 8878, 2022 p. 27-32, Open Access logo Open Access
PublisherNatural Resources Canada
MeetingMontney H2S, Distribution and Origin Workshop; Calgary, AB; CA; February 9, 2022
Documentopen file
Mediadigital; on-line
RelatedThis publication is contained in Hydrogen sulfide (H2S) in the Montney Formation, Western Canada Sedimentary Basin (WCSB) - investigating a complex issue, workshop proceeding
File formatpdf
ProvinceAlberta; British Columbia
NTS83C; 83E; 83F; 83G; 83J; 83K; 83L; 83M; 83N; 83O; 84B; 84C; 84D; 84E; 84F; 84G; 84L; 93I; 93O; 93P; 94A; 94B; 94G; 94H; 94I; 94J
AreaFort St. John; Grande Prairie
Lat/Long WENS-123.5000 -115.7500 59.0000 53.0000
Subjectsfossil fuels; geochemistry; sedimentology; Science and Technology; Nature and Environment; Lower Triassic; sedimentary basins; petroleum resources; hydrocarbons; reservoirs; hydrogen sulphide; sulphur geochemistry; isotopic studies; sulphur; sulphates; sulphides; modelling; models; source areas; source rocks; fluid migration; flow structures; structural controls; geological history; diagenesis; alteration; dolomitization; tectonic history; burial history; crustal uplift; orogenies; pressure-temperature conditions; bedrock geology; structural features; faults; fractures; petrography; Montney Formation; Western Canada Sedimentary Basin; Laramide Orogeny; Methodology; Quality control; Phanerozoic; Mesozoic; Triassic
Illustrationsgeoscientific sketch maps; stratigraphic charts; photomicrographs; plots
ProgramEnergy Geoscience Clean Energy Resources - Decreasing Environmental Risk
ProgramGeoscience for New Energy Supply (GNES)
Released2022 03 22
AbstractHydrogen sulfide (H2S) is a toxic and corrosive gas that commonly occurs in deeply buried sedimentary systems. Understanding its distribution is paramount to creating safe and effective models of H2S occurrence aiding in the identification of high-risk areas. Characterizing subsurface sulfur sources and H2S formation pathways would enhance these models leading to more accurate predictions of potential high H2S regions. However, gaps remain in our understanding of the dominant formation processes and migration pathways of key ingredients for H2S production in the Lower Triassic Montney Formation of the Western Canada Sedimentary Basin (WCSB). Essential to this is assessing the reactants necessary for H2S production, potential pathways for fluid migration, diagenetic history, and changes in redox conditions through time.
The Montney Formation has undergone several phases of diagenesis related to post-depositional alteration and multiple cycles of tectonic burial and uplift. Early chemical alteration includes dolomitization and, in some cases, microbial reduction of porewater sulfate to sulfide that occurred prior to significant burial (Davies et al., 1997; Vaisblat et al., 2021; Liseroudi et al., 2020, 2021). The most recent tectonic-related burial during the Laramide Orogeny resulted in burial depths in excess of 3-5 km (Ness, 2001; Ducros et al., 2017) leading to significant thermal and barometric alteration. Associated with this orogenic activity was the reactivation of underlying faults (O'Connell et al., 1990) and development of fractures especially near the deformation front. These fractures provide conduits for fluid migration into the Montney that combined with heat and pressure resulting in hydrocarbon generation, migration, and development of overpressure, notably in the western margin of the basin. In addition, high temperatures resulted in thermochemical sulfate reduction (TSR) leading to the formation of H2S and subsequently pyrite.
We present an interpretation of the Montney subsurface sulfur cycle through the use of petrography, micro- and macro-scale geochemical analysis (isotopic and elemental) to illustrate the complexity of this system. This work relies heavily on previous studies within and outside our research group and incorporates new analytical techniques to expand the toolbox. We aim to guide future research directions and activities by addressing issues related to sampling and data quality issues, analytical approaches, and highlight knowledge gaps.
Summary(Plain Language Summary, not published)
The origin and distribution of hydrogen sulfide (H2S) - a highly toxic and corrosive gas in conventional and unconventional resources of the Western Canada Sedimentary Basin - was the subject of many studies. The Early Triassic Montney Formation, one of the major North American unconventional gas resources, contains a significant amount of H2S in some areas. Several research teams in western Canada including the Geological Survey of Canada, the University of Calgary, and the University of British Columbia are investigating this complex issue. This workshop will provide a venue to discuss the latest scientific advancements on this topic in order to reach a better understanding of the distribution, origin, and mitigation strategies to overcome the associated economic and environmental issues. This open file report presents the proceedings of the online workshop 'Hydrogen sulfide (H2S) in the Montney Formation - investigating a complex issue' on February 9th, 2022 in Calgary Alberta, organized by the Canadian Society for Unconventional Resources (CSUR), Natural Resources Canada (NRCan), and University of Calgary.

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