| Titre | Origin of sulfate-rich fluids in the Early Triassic Montney Formation, Western Canadian Sedimentary Basin |
| |
| Auteur | Liseroudi, M H; Ardakani, O H ; Sanei, H; Pedersen, P K; Stern, R A; Wood,
J M |
| Source | Marine and Petroleum Geology vol. 114, 104236, 2020 p. 1-17, https://doi.org/10.1016/j.marpetgeo.2020.104236 |
| Année | 2020 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20180141 |
| Éditeur | Elsevier |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1016/j.marpetgeo.2020.104236 |
| Media | papier; en ligne; numérique |
| Formats | pdf; html; xml |
| Province | Alberta; Colombie-Britannique |
| SNRC | 83L/09; 83L/10; 83L/11; 83L/12; 83L/13; 83L/14; 83L/15; 83L/16; 83M; 84D; 84E/03; 84E/04; 93I/09; 93I/16; 93P/01; 93P/02; 93P/06; 93P/07; 93P/08; 93P/09; 93P/10; 93P/11; 93P/13; 93P/14; 93P/15; 93P/16; 94A;
94B/01; 94B/08; 94B/09; 94B/16; 94G/01; 94H/01; 94H/02; 94H/03; 94H/04 |
| Région | Dawson Creek |
| Lat/Long OENS | -122.3333 -118.0000 57.2500 54.6667 |
| Sujets | Trias inférieur; diagenèse; fluides de formation; dynamique des fluides; origine; sulfates; anhydrite; barytine; pyrite; roches reservoirs; hydrogene sulfuré; gaz sulfreux; paragenèse; cimentation;
fractures; études des isotopes stables; radioisotopes; soufre; oxygène; rapports strontium-strontium; géologie du substratum rocheux; géologie du socle; roches sédimentaires; siltstones; schistes; évaporites; analyse par spectromètre de masse;
échantillons carrotés; analyses pétrographiques; système hydrothermal; contrôles structuraux; Formation de Montney ; Bassin sédimentaire de l'ouest canadien; combustibles fossiles; sédimentologie; géochimie; Sciences et technologie; Nature et
environnement; Phanérozoïque; Mésozoïque; Trias; Paléozoïque; Dévonien |
| Illustrations | cartes de localisation; cartes géolscientiques généralisées; échelles stratigraphiques; coupes transversales; tableaux; photomicrographies; photographies; diagrammes; graphiques; profils; séries
chronologiques |
| Programme | Les géosciences pour les nouvelles sources d'énergie Caractérisation des réservoirs de schiste |
| Diffusé | 2020 01 11 |
| Résumé | (disponible en anglais seulement)
This study investigates diagenetic and geochemical processes that control regional distribution and formation of sulfate minerals (i.e., anhydrite and barite)
in the Early Triassic Montney Formation in the Western Canadian Sedimentary Basin. The generation of H2S in hydrocarbon reservoirs is often associated with the dissolution of sulfate minerals, as a major source of sulfate required for
sulfate-reducing reactions. The formation of pervasive late diagenetic anhydrite and barite in the high H2S zone of the Montney Formation is therefore contrary to the normal paragenetic sequence of sour gas reservoirs.
Petrographic observations
revealed early and late anhydrite and barite cement. The early fine-crystalline anhydrite cement is dominant in northeastern British Columbia (low H2S zone), while the late-stage coarse-crystalline cement and fracture/vug-filling anhydrite are
dominant in Alberta (high H2S zone). The bulk isotopic values (delta-34S: +2.9 to +24.7 per mille V-CDT, delta-18O: -11.2 to +15.7 per mille V-SMOW) suggest that sulfate-rich fluids originated mainly from modified Triassic connate water was the
origin of early anhydrite. In contrast, the SIMS isotopic values of late anhydrite (delta-34S: +18.5 to +37 per mille V-CDT, delta-18O: +12 to +22 per mille V-SMOW) and barite cement (delta-34S: +23.3 to +39 per mille V-CDT, delta-18O: +13.2 to +18.7
per mille V-SMOW) as well as fracture/vug-filling anhydrite (delta-34S: +23.5 to +24.7 per mille V-CDT, delta-18O: +13.3 to +14.7 per mille V-SMOW) from Alberta represents a mixed isotopic signature of Triassic connate water and contribution of
dissolved sulfate-rich fluids derived from dissolution of Devonian evaporites.
The 87Sr/86Sr isotope ratios of the fracture/vug-filling anhydrite (0.7092-0.7102) are highly radiogenic suggesting extensive water/rock interactions between
sulfate-rich fluids and siliciclastic and basement rocks. The similar isotopic composition of the late anhydrite/barite and fracture/vug-filling anhydrite in western Alberta with Devonian evaporites isotopic signature, and the highly radiogenic
87Sr/86Sr ratio further supports sulfate-bearing fluids were mainly originated from underlying Devonian evaporites and migrated upwards through deep-seated faults/fractures to the Montney Formation. |
| Sommaire | (Résumé en langage clair et simple, non publié)
De fortes concentrations de H2S dans les puits gazifères de la Formation de Montney, dans l'ouest de l'Alberta, ont soulevé des inquiétudes
quant à l'impact économique de l'extraction et du traitement du gaz naturel et de ses impacts environnementaux négatifs. Cette étude porte sur les processus diagénétiques et géochimiques qui contrôlent la production de H2S et sa variation régionale
dans le jeu de gaz naturel serré du siltite de Montney du Trias inférieur dans le bassin sédimentaire de l'Ouest canadien (BSOC). |
| GEOSCAN ID | 308446 |
|
|