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TitleDiagenetic and geochemical controls on H2S distribution in the Montney Formation, Peace River region, western Canada
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LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorLiseroudi, M H; Ardakani, O HORCID logo; Pedersen, P KORCID logo; Stern, R A; Wood, J M; Sanei, HORCID logo
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. 14-24, 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
NTS83L; 83M; 84D; 84E; 93I; 93O; 93P; 94A; 94B; 94G; 94H
AreaDawson Creek; Peace River
Lat/Long WENS-122.5000 -118.0000 57.5000 54.5000
Subjectsfossil fuels; geochemistry; sedimentology; mineralogy; Science and Technology; Nature and Environment; Lower Triassic; sedimentary basins; petroleum resources; hydrocarbons; reservoir rocks; hydrocarbon recovery; gas wells; hydrogen sulphide; gas; diagenesis; pore fluids; water geochemistry; hydrothermal systems; fluid migration; flow structures; structural controls; sulphates; sulphides; pyrite; anhydrite; barite; morphology, crystal; mineral distribution; isotopic studies; sulphur geochemistry; oxygen isotopes; sulphur isotope ratios; Montney Formation; Western Canada Sedimentary Basin; Phanerozoic; Mesozoic; Triassic; Paleozoic; Devonian
Illustrationslocation maps; geoscientific sketch maps; photomicrographs; plots; geochronological charts; bar graphs; schematic cross-sections; schematic representations
ProgramEnergy Geoscience Clean Energy Resources - Decreasing Environmental Risk
ProgramGeoscience for New Energy Supply (GNES)
Released2022 03 22
AbstractThe Lower Triassic Montney Formation is a major siltstone dominated unconventional tight gas play in the Western Canadian Sedimentary Basin (WCSB). In the Peace River region, the Montney Formation contains a regionally variable amount of hydrogen sulfide (H2S) in gas-producing wells with western Alberta's wells having the highest concentrations. Previous studies on the source and distribution of H2S in the Montney Formation mainly focused on variations of H2S concentration and its relationship with other hydrocarbon and non-hydrocarbon gases, sulfur isotope composition of H2S, as well as organo-sulfur compounds in the Montney Formation natural gas. None of those studies, however, focused on the role of diagenetic and geochemical processes in the formation of dissolved sulfate, one of the two major ingredients of H2S formation mechanisms, and pyrite within the Montney Formation.
According to the results of this study, the Montney Formation consists of two different early and late generations of sulfate minerals (anhydrite and barite), mainly formed by the Montney Formation pore water and incursion of structurally-controlled Devonian-sourced hydrothermal sulfate-rich fluids. In addition, pyrite the dominate sulfide mineral, occurred in two distinct forms as framboidal and crystalline that formed during early to late stages of diagenesis in western Alberta (WAB) and northeast British Columbia (NEBC). The concurrence of the late-stage anhydrite and barite and various types of diagenetic pyrite with high H2S concentrations, particularly in WAB, their abundance, and spatial distribution, imply a correlation between the presence of these sulfate and sulfide species and the diagenetic evolution of sulfur in the Montney Formation.
The sulfur isotope composition of anhydrite/barite, H2S, and pyrite demonstrates both microbial and thermochemical sulfate reduction (MSR and TSR) controlled the diagenetic sulfur cycle of the Montney Formation. The relationship between the delta-34S values of the present-day produced gas H2S and other sulfur-bearing species from the Montney and other neighboring formations verifies a dual native and migrated TSR-derived origin for the H2S gas with substantial contributions of in situ H2S in the Montney reservoir.
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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