Sedimentology, depositional environment, and reservoir properties of the Silurian Interlake Formation, southern Saskatchewan
Notice bibliographique
Résumé
The Interlake Formation, located in southern Saskatchewan, dates to the Early Silurian period and was deposited on the northern shelf of the Williston Basin. The formation is characterized by dolostone lithology and spans southwestern Manitoba, eastern Alberta, and neighbouring U.S. states. Late Ordovician – early Silurian glacio-eustatic sea level drop resulted in a stratigraphic temporal gap between the Upper Ordovician Stonewall Formation and the Lower Silurian Interlake Formation. Cores, wireline logs, and petrographic information were gathered from 30 wells and analyzed from the research area. The results indicate that the formation can be categorized into three informal members: lower, middle, and upper. The lower member comprises bioturbated dolostone lithofacies and minor reddish argillaceous dolomudstone. The latter serve as marker beds that facilitate correlation within the study area. The middle member consists of thickly laminated, bioclastic dolomudstone characterized by marine fauna. The upper member is distinguished by diverse intraclastic and sparse/nonfossiliferous dolostone facies, subordinate anhydrite layers and nodules. Seams of argillaceous dolomudstone at the millimetre scale are also visible. The core and petrographic analyses of the formation allow the identification of six lithofacies: Lf1-Lf6. The lithofacies properties, sedimentary structures and textures, fossil content, and lithofacies associations suggest that the formation was deposited in a shallow marine environment, ranging from intraclastic and bioclastic dolopackstone/grainstone subtidal shoals to landward lagoonal (restricted) environment to peloidal and bioclastic dolomudstone/wackestone intertidal and supratidal mudflat settings. The diverse lithofacies are organized in meter-scale cycles of shallowing-upward successions, believed to be influenced by Milankovitch Sea level fluctuations. The lithofacies configuration of the analyzed stratigraphic interval exhibits distinct vertically stacked rhythmic units of basal subtidal lithofacies (Lf5, Lf3) transitioning to restricted lagoonal/intertidal (Lf4) to supratidal mud-flat deposits (Lf2, Lf1, and Lf6). The examination of cyclicity plots for these rhythmic units indicates elevated 4th to 5th-order Milankovitch cycles, which can be categorized as a stack of 3rd-order depositional cycles. The 4th-order cycles exhibit a strong correlation with the Silurian cyclothems, resulting from slow basin subsidence and eustatic sea level fluctuations. The identified diagenetic products and paragenetic sequence from core logs, petrographic, and SEM analysis include micritization and micrite envelope, various instances of calcite cementation, dolomitization, anhydrite cementation, dewatering and dissolution, compaction fracturing, stylolite formation and pyrite filling. The principal diagenetic processes influencing the porosity evolution of the Interlake Formation include cementation, compaction, dolomitization, and dissolution. The primary and secondary porosity of the various lithofacies of the Interlake Formation encompasses intercrystalline, fracture, vuggy, intracrystalline, and fenestrae porosities. Variations in porosity and permeability among the lithofacies of the Interlake Formation arise from differing degrees of porosity-destruction and porosityenhancement characteristics. The Lower Interlake demonstrates good porosity (average 12%) and permeability (average 15.9 millidarcies), and the Middle Interlake displays moderate porosity (average 5%) and permeability (average 5.2 millidarcies). In contrast, the Upper Interlake reveals comparatively low porosity (average 3%) and higher permeability (average 28 millidarcies). Thus, the lower member shows the best reservoir potential (conventional reservoir where f>5%), the middle member is at the boundary between conventional and unconventional reservoirs, and the upper member is an unconventional reservoir (f<5%). The Interlake Formation is a candidate for potential CO2 sequestration.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,003 |
| Études des sciences et des technologies | 0,001 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».