| Titre | Delta-13C, delta-18O and 87Sr/86Sr isotope composition of Montney Formation carbonate phases: implications for the nature of diagenetic fluids |
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| Auteur | Liseroudi, M H; Ardakani, O H ; Sanei, H; Pedersen, P K; Spencer, R J;
Wood, J M |
| Source | Geoconvention 2019, technical program; 2019 p. 1  Accès
ouvert |
| Liens | Online - En ligne (PDF, 147 KB)
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| Image |  |
| Année | 2019 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20180340 |
| Réunion | Geoconvention 2019; Calgary; CA; mai 13-15, 2019 |
| Document | site Web |
| Lang. | anglais |
| Media | numérique; en ligne |
| Formats | pdf (Adobe® Reader®) |
| Province | Colombie-Britannique; Alberta |
| SNRC | 84E/05; 84E/06; 84E/11; 84E/12; 84E/13; 84E/14; 94H/06; 94H/07; 94H/08; 94H/09; 94H/10; 94H/11; 94H/14; 94H/15; 94H/16 |
| Lat/Long OENS | -121.5000 -119.0000 58.0000 57.2500 |
| Sujets | ressources pétrolières; hydrocarbures; gaz; etudes isotopiques; isotopes de carbone; isotopes d'oxygène; rapports strontium-strontium; géologie du substratum rocheux; lithologie; roches sédimentaires;
siltstones; carbonate; calcite; dolomites; diagenèse; fluides du réservoir; régions émettrices; analyses pétrographiques; historique de l'enfouissement; Formation de Montney ; combustibles fossiles; géochimie; sédimentologie; Sciences et technologie;
Phanérozoïque; Mésozoïque; Trias |
| Programme | Les géosciences pour les nouvelles sources d'énergie Caractérisation des réservoirs de schiste |
| Diffusé | 2019 05 01 |
| Résumé | (disponible en anglais seulement)
The Montney Formation, western Canada's leading unconventional tight gas play, is a siltstone-dominated reservoir with a complex diagenetic history. Previous
diagenetic studies of the Montney Formation are mainly centered on the effect of diagenesis on reservoir quality and porosity evolution with minimal application of isotopic studies to address water-rock interaction and origin of diagenetic fluids in
this Formation. This study presents preliminary results of petrographic studies and bulk stable isotope data from calcite and dolomite plus bulk 87Sr/86Sr ratio analyses to investigate the nature of the diagenetic fluid(s) and geochemical processes
involved during diagenesis of the Montney Formation in western Alberta and northeastern BC.
Petrographic studies show that dolomite occurs as ferroan zoned and non-ferroan pore-filling cement, mostly nucleated on rounded detrital grains. Calcite
exists as non-ferroan to ferroan pore-filling, ferroan replacive, and non-ferroan poikilotopic cement. The delta-13C and delta-18O values of dolomite range from -6.5 to 0.4 permille (V-PDB) and -2.8 to -7.8 permille (V-PDB), respectively. Calcite
exhibits similar delta-13C values to dolomite ranging from -0.1 to -7.1 permille (V-PDB) with a narrower range of delta-18O values varying from -6.0 to -9.5 permille (V-PDB). The preliminary 87Sr/86Sr isotope composition of three measured samples
varies from 0.7105 to 0.7111.
Carbon and oxygen isotope composition of both calcite and dolomite are depleted in comparison to the reported range of delta-13C and delta-18O for the Triassic marine calcite and dolomite. This suggests that the
isotopic composition of the Montney Formation carbonates is strongly influenced by diagenetic fluids that originated from source(s) other than the Triassic seawater derived pore water. Calcite and dolomite from northeastern BC are more depleted in
18O correlating with elevated burial temperature of the Montney Formation in this region. The 18O -depleted dolomite from the area of lower burial temperature in western Alberta is likely linked to hydrothermal activity. Negative delta-13C values of
both calcite and dolomite are probably indicative of diagenetic fluids depleted in 13C derived from decomposition of organic matter during burial. Preliminary 87Sr/86Sr ratio analysis also suggests that Montney Formation carbonate phases were formed
from fluids enriched in radiogenic Sr isotope. Further work is underway to determine the strontium isotopic composition of individual phases. This may further confirm contribution of fluids other than coeval Triassic pore water to precipitation of
carbonates in the Montney Formation. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Cette étude présente les résultats préliminaires d'études pétrographiques et de données d'isotopes stables en vrac, obtenues à partir d'analyses
de calcite et de dolomite et du rapport masse 87Sr / 86Sr en vrac, afin d'étudier la nature du ou des fluides diagénétiques et les processus géochimiques impliqués lors de la diagenèse de la formation de Montney dans l'ouest de l'Alberta et AVANT
JC. |
| GEOSCAN ID | 313393 |
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