| Title | A reappraisal of the regional hydrocarbon potential of the Scotian Shelf |
| Download | Downloads |
| Author | Nantais, P T |
| Source | Geological Survey of Canada, Open File 1175, 1985, 179 pages, https://doi.org/10.4095/130007 |
| Year | 1985 |
| Publisher | Geological Survey of Canada |
| Document | open file |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Eastern offshore region; Nova Scotia |
| NTS | 10I/13; 10I/14; 10J/13; 10J/14; 10J/15; 10J/16; 10K/13; 10K/14; 10K/15; 10K/16; 10L/15; 10L/16; 10M/01; 10M/08; 10M/09; 10M/16; 10M/02; 10M/07; 10M/10; 10M/15; 10N; 10O; 10P/04; 10P/05; 10P/12; 10P/13;
10P/03; 10P/06; 10P/11; 10P/14; 11A/04; 11A/05; 11A/12; 11A/13; 11A/03; 11A/06; 11A/11; 11A/14; 11B; 11C; 11D/01; 11D/08; 11D/09; 11D/16; 11D/02; 11D/07; 11D/10; 11D/15; 11E/01; 11E/02; 11F/01; 11F/02; 11F/03; 11F/04; 11G/01; 11G/02; 11G/03; 11G/04;
11H/04; 11H/03 |
| Area | Scotian Shelf |
| Lat/Long WENS | -63.0000 -57.0000 46.0000 42.7500 |
| Subjects | geochemistry; fossil fuels; petroleum resources; hydrocarbons; models; organic maturity; gas; oil; salt domes; diapirs; geothermal gradient; organic carbon; Scotian Shelf; Verrill Canyon Formation;
terrestrial deposit; Phanerozoic; Mesozoic; Cretaceous; Jurassic; Triassic |
| Illustrations | location maps; cross-sections; geochronological charts; graphs; sketch maps; pie charts; tables; stratigraphic charts; profiles; charts; models; plots; schematic representations; schematic
cross-sections; logs |
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| Natural Resources Canada Library - Ottawa (Earth Sciences) |
| Natural Resources Canada library - Vancouver (Earth Sciences) |
| Natural Resources Canada library - Calgary (Earth Sciences) |
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| Released | 1985 09 01; 2017 03 07 |
| Abstract | The hydrocarbon potential of the Scotian Shelf has been re-evaluated in light of recent data provided by increased exploration activity and new oil and gas generation models for terrestrial organic
matter. Geothermal gradient data, based on corrected downhole temperatures, has been updated and revised. Regionally, patterns on geothermal gradient maps reflect basement topography and the presence or absence of salt at depth. Locally, the primary
control is sand/shale ratio and the presence of carbonates. Subsurface fluids have resulted in a geothermal high coincident with the carbonate front at the western end of the Sable Subbasin. Higher primary heat flux from the basement hinge zone may
also be a factor. Patterns of organic matter types and total organic carbon have been investigated and found to be related to age and paleoenvironment. The gas-condensate nature of the hydrocarbons on the shelf is attributed to the terrestrial nature
of the organic material. Only late Middle-early Late Jurassic sediments possess enough amorphous material to source liquid hydrocarbons. A variety of maturation indicators including %R0 , TTI, TAI, cuttings gas analyses and temperature have been
calibrated. Absolute values vary with basinal position due to the age of the sediments and subsidence rate. Only the lowermost Cretaceous and older section can be termed fully mature. At high rates of heating, TAI responds more quickly than
vitrinite, which may explain the apparent discrepancies between maturation indicators over the Primrose salt diapir. Oil generation in the Abenaki Subbasin, LaHave Platform, Orpheus Graben and Scotian slope is unlikely. The organic matter is of
insufficient quantity and quality to source oil. The LaHave Platform is immature to basement. Some dry gas may be sourced from shales and coal beds within the Missisauga and/or MicMac Formations of the Abenaki Aubbasin. Due to rapid subsidence and
short cooking times, shales on the slope are unlikely to source oil. There is also some question as to the existance of reservoir facies or migration pathways to shallower reservoirs in this area. In the Sable Island area, potential source rocks have
good communication with reservoir facies, however, to the south, the fully mature zone occurs within a thick shale section and migration pathways are restricted. Oil on the shelf is the consequence of maturation of organic matter which was
preferentially preserved under unique environmental conditions. A mechanism must exist whereby the deep, mature shales can be drained. The lack of oil found in seaward wells with communication to potential source beds reflects insufficient maturation
and/or deterioration of source rock potential. A hydrocarbon generating model has been constructed for the Scotian Shelf based on total organic carbon, gas to condensate or oi l ratios, observed maturation and known hydrocarbon discoveries. The model
applies only to the Scotian Shelf and to terrestrial organic matter. |
| GEOSCAN ID | 130007 |
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