Thermal Maturity and Source-Rock Potential in Northwestern Melville Island, Arctic Canada
Title:
Thermal Maturity and Source-Rock Potential in Northwestern Melville Island, Arctic Canada
Author:
Gentzis, Thomas Goodarzi, Fariborz
Appeared in:
Energy sources. Part A, Recovery utilization and environmental effects
Paging:
Volume 14 (1992) nr. 4 pages 423-442
Year:
1992-10-01
Contents:
Approximately 130 core and drillhole cuttings samples taken from the Palaeozoic and Mesozoic of northwestern Melville Island were examined using reflected-light microscopy and Rock-Eval pyrolysis. The Triassic Schei Point marine silty shales, known to be good-quality source rocks in certain parts of the Sverdrup Basin, are dominated by kerogen Types I and II, have hydrogen index (HI) values as high as 625 mg hydrocarbon (HC)/g organic carbon, a total organic carbon (TOC) content as high as 8.07o, but are marginally mature at best. Source potential decreases drastically in the Jurassic and Cretaceous parts of the succession The Palaeozoic section is dominated by bitumen, and often numerous bitumen populations are identified based on morphology, texture, and optical properties. Bitumen reflectance increases with depth, following a trend almost parallel to vitrinite, an indication that it is primary and has been subjected to similar thermal stress. The upper Palaeozoic sediments are within the hydrocarbon generation zone but have limited potential, except for an algal-rich interval in the Permian Trold Fiord Formation. To the contrary, the lower Palaeozoic sediments are in the overmature zone of hydrocarbon generation, and only gas should be expected. Using bitumen reflectance it is estimated that approximately 7.0 km of section may have been eroded at the boundary between the lbbett Bay and Canyon Fiord Formations due to the Ellesmer-ian Orogeny. This has been verified by stratigraphic and structural evidence. Overall, the study is important because it attempts to identify the source rocks in an area of Melville Island where no previous work has been reported on the hydrocarbon-generating potential of the sedimentary succession. In addition, the use of bitumen reflectance in lower Palaeozoic strata devoid of vitrinite is evaluated and the amount of eroded section is calculated based on the thermal maturiry pattern of bitumen.
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