| Titre | Synthesis of organic matter composition and maturation and gas data from selected deep source rock units for some wells in the Fox Creek area |
| Télécharger | Téléchargements |
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| Licence | Veuillez noter que la Licence du gouvernement
ouvert - Canada remplace toutes les licences antérieures. |
| Auteur | Lavoie, D ;
Ardakani, O H; Rivard, C |
| Source | Commission géologique du Canada, Dossier public 8788, 2021, 95p., https://doi.org/10.4095/328238  Accès ouvert |
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| Année | 2021 |
| Éditeur | Ressources naturelles Canada |
| Document | dossier public |
| Lang. | anglais |
| DOI | https://doi.org/10.4095/328238 |
| Media | en ligne; numérique |
| Formats | pdf |
| Province | Alberta |
| SNRC | 83F |
| Région | Fox Creek |
| Lat/Long OENS | -118.0000 -116.0000 54.0000 53.0000 |
| Sujets | ressources en eau souterraine; aquifères; pollution de l'eau souterraine; industrie pétrolière; exploration pétrolière; hydrocarbures; gaz; pétrole; charbon; maturation thermique; etudes isotopiques;
isotopes de carbone; pyrolyse; roches mères; analyses pétrographiques; milieu sédimentaire; réflectance; réflectance de la vitrinite; temperature; puits; géologie du substratum rocheux; lithologie; roches sédimentaires; grès; conglomérats; calcaires;
dolomies; carbonates; roches clastiques; évaporites; schistes; siltstones; mudstones; Paléogène; Paléocène; Bassin sédimentaire de l'ouest du Canada; Formation de Duvernay ; Formation de Montney ; Formation de Fernie ; Membre de Nordegg ; Groupe de
Mannville ; Formation de Paskapoo ; Méthodologie; Évaluation environnementale; effets cumulatifs; hydrogéologie; géologie de l'environnement; combustibles fossiles; Économie et industrie; Nature et environnement; Sciences et technologie;
Phanérozoïque; Cénozoïque; Tertiaire; Mésozoïque; Crétacé; Jurassique; Trias; Paléozoïque; Dévonien |
| Illustrations | diagrammes stratigraphiques; diagrammes; photomicrographies; tableaux; cartes de localisation; graphiques; profils |
| Programme | Géosciences environnementales Impacts potentiels des activités liées au développement gazier et pétrolier sur les aquifères non salins, Fox
Creek |
| Diffusé | 2021 04 28 |
| Résumé | (disponible en anglais seulement)
An analysis of historical and new organic matter data, as well as gas composition and isotopic ratios for deep hydrocarbon source rocks, is part of a holistic
study of the potential environmental impact of unconventional hydrocarbon development in the Fox Creek area in Alberta. The goal of this activity is to use thermal maturation and gas data from deep source rocks to generate a database for the
interpretation of source rocks for eventual dissolved hydrocarbons in shallow groundwater.
The organic matter study consists of new petrographic observations on pellets from the Duvernay, Montney, Nordegg, and Mannville organic-rich samples. The
petrography indicates that the organic matter is of marine Type II origin with one coal (Type III) sample in the Mannville Group. The organic matter reflectance measurements were taken on bitumen and converted to equivalent vitrinite reflectance
values; vitrinite reflectance has been directly measured from the coal sample. The data indicate that all units reached thermal conditions for the production of hydrocarbons. The deep Duvernay Formation has the highest thermal maturity data that
suggest the end of the oil window in the eastern end of the study area and the onset of the condensate zone in the western part of the study area.
Rock-Eval data from publicly available wells in the GSC database were evaluated for the Duvernay,
Montney, and Nordegg units. The Tmax values indicate that these units are within the hydrocarbon production zones. As with the vitrinite-equivalent data, the Duvernay Formation has reached the highest thermal maturity in the study area with values
indicative of the condensate zone, the other units belong to the oil zone.
Gas samples were collected in isotubes at the time of drilling. Samples were collected at various depths with some wells having only a short interval with data, while
others have samples from a much longer interval. Data from 7 wells were available for our study, 6 of the wells are located at the eastern end of the study area while the last one is much further north. From gas composition (wetness ratio:
C1/(C2+C3)) and delta-13C ratios of methane, the origin of the gas is thermogenic. The vertical trends of delta-13C ratios of ethane versus depth and wetness, as well as butane ratios (iC4/nC4) versus depth and wetness for wells with a longer
distribution of samples, suggest partial isotopic rollover. The roll-over was not fully developed as nowhere do we see delta-13C ratios of ethane being lighter (more negative) than that delta-13C ratio of methane. This suggests, as supported by the
organic matter reflectance and Rock-Eval data, that the study area never reached very high thermal conditions. The fact that significant statistical overlap of delta-13C ratios of methane and the inverted trend of delta-13C ratios for ethane
challenges the use of these isotopes data for source interpretation of eventual dissolved hydrocarbons in groundwater. However, some limited data for the shallowest sampling intervals (<1500 m) in some wells suggest that more significantly different
data might be present in shallower sections in the subsurface. Data from eventual shallow coals intercepted by monitoring wells to be drilled are considered critical for the interpretation of the source for eventual dissolved hydrocarbons in
groundwater. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Une analyse des données historiques et nouvelles sur la matière organique, ainsi que sur la composition du gaz et les rapports isotopiques des
roches mères profondes d'hydrocarbures, fait partie d'une étude holistique de l'impact environnemental potentiel de l'exploitation des hydrocarbures non conventionnels dans la région de Fox Creek en Alberta. L'objectif de cette activité est
d'utiliser la maturation thermique et les données sur les gaz provenant des roches mères profondes afin de créer une base de données pour l'interprétation des roches mères en vue d'éventuels hydrocarbures dissous dans les eaux souterraines peu
profondes. |
| GEOSCAN ID | 328238 |
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