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Organic petrography and geochemical characterization of the Upper Cretaceous Second White Specks and Upper Belle Fourche alloformations, west-central Alberta: Analysis of local maturity anomalies.

Authors :
Aviles, Mailyng A.
Ardakani, Omid H.
Cheadle, Burns A.
Sanei, Hamed
Source :
International Journal of Coal Geology. Feb2019, Vol. 203, p60-73. 14p.
Publication Year :
2019

Abstract

Abstract The Second White Specks is an enigmatic unconventional shale play in the Western Canada Foreland Basin (WCFB). This play has an inconsistent production performance that has impacted exploration and production risk, preventing extensive development. In this contribution, geochemical properties are studied with the purpose to identify possible geochemical factors that could contribute to the production variability of this unconventional petroleum system. The studied succession consists of the Second White Specks (SWS) and Upper Belle Fourche (UBF) alloformations, which are part of the SWS shale play. Organic petrology and Rock-Eval pyrolysis were combined to characterize the organic matter (OM), and assess OM richness, thermal maturity and hydrocarbon generation potential in the foredeep section of the basin. The results show that the OM richness and hydrocarbon generation potential in this area is good, and comparison with other studies show that they do not exhibit major lateral variations. The kerogen is marine Type II and is dominated by liptinite, vitrinite, inertinite macerals, and solid bitumen. Alginite and bituminite are the most abundant macerals. Altered bituminite provides evidence of anaerobic bacteria degradation. There is a modest contribution of inertinite that may be responsible for a dilution effect of the pyrolyzable carbon. The thermal maturity indicators in this study such as vitrinite reflectance, Tmax, and alginite UV fluorescence color indicate that the controls on thermal maturity and hydrocarbon generation are not well understood. There are lateral short scale variations or maturity anomalies that require further investigation, to reduce the exploration risk. Highlights • Exsudatinite, bituminized alginite and oil inclusions corroborate endogenous hydrocarbon generation. • The thermal maturity in most of the study area indicates onset of petroleum generation to peak oil window. • A low maturity anomaly was identified. Further research is needed to test hypotheses for lateral maturity variability. • The organic matter experienced several degrees of anaerobic degradation. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
01665162
Volume :
203
Database :
Academic Search Index
Journal :
International Journal of Coal Geology
Publication Type :
Academic Journal
Accession number :
134754079
Full Text :
https://doi.org/10.1016/j.coal.2019.01.008