| Title | Organic petrography and thermal maturity of the Paskapoo Formation in the Fox Creek area, west-central Alberta |
| Download | Downloads |
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| Licence | Please note the adoption of the Open Government Licence - Canada
supersedes any previous licences. |
| Author | Ardakani, O H |
| Source | Geological Survey of Canada, Open File 8903, 2022, 20 pages, https://doi.org/10.4095/330296  Open Access |
| Image |  |
| Year | 2022 |
| Publisher | Natural Resources Canada |
| Document | open file |
| Lang. | English |
| Media | digital; on-line |
| File format | pdf |
| Province | Alberta |
| NTS | 83K/02; 83K/03; 83K/04; 83K/05; 83K/06; 83K/07 |
| Area | Fox Creek; Tony Creek |
| Lat/Long WENS | -118.0000 -116.5000 54.5000 54.0000 |
| Subjects | fossil fuels; geochemistry; hydrogeology; Science and Technology; Nature and Environment; Paleogene; Paleocene; petroleum resources; hydrocarbons; hydrocarbon potential; coal seams; source rocks;
groundwater resources; aquifers; groundwater pollution; petrography; thermal maturation; observation wells; organic geochemistry; pyrolysis; environmental impacts; biogenic gas; methane; vitrinite reflectance; bedrock geology; lithology; sedimentary
rocks; sandstones; shales; siltstones; sediments; tills; Paskapoo Formation; Phanerozoic; Cenozoic; Tertiary |
| Illustrations | stratigraphic charts; tables; sketch maps; profiles; plots; photomicrographs; charts |
| Program | Environmental Geoscience Potential impacts of oil and gas development on non-saline aquifers, Fox Creek |
| Released | 2022 07 05 |
| Abstract | The Paskapoo Formation, which ranges in age from middle to upper Paleocene, is the major shallow aquifer in Alberta. This study is part of a larger GSC-led study on the potential environmental impact of
hydrocarbon development in the Fox Creek area (west-central Alberta) on shallow aquifers. Fox Creek is located near the northern limit of the Paskapoo Formation. In addition to the underlying organic-rich source rocks in the study area, including the
Duvernay Formation that is currently exploited for hydrocarbon resources, the Paskapoo Formation contains organic-rich intervals and coal seams. In order to investigate any potential internal hydrocarbon sources within the Paskapoo Formation,
ninety-seven (97) cutting samples from the formation obtained from eight shallow monitoring wells (50-90 m) in the study area were studied for total organic carbon (TOC) content, organic matter composition and thermal maturity of coal seams using
programmed pyrolysis analysis and organic petrography.
The TOC content of all samples ranges from 0.2 to 8.8 wt. %, with a mean value of 0.95 ± 1.6 wt. % (n=97). The Tmax values of studied samples range from 347 to 463 °C, with a mean value of 434
± 20 °C that suggest a range of thermal maturity from immature to peak oil window. The random reflectance (Rr) measurement and fluorescence microscopy on eighteen (18) selected samples with TOC content > ~1 wt. % shows a mean Rr value of 0.27% and
0.42% for the overlying till deposits and the underlying shallow depth sandstone, siltstone, shale and coal seams respectively, indicating a low rank coal ranging from lignite to sub-bituminous coal. Blue to green and yellow fluorescing liptinite
macerals further confirmed the low maturity of studied samples. The low S2 yield of a large part of the samples (65%) resulted in unreliable Tmax values that overestimated the thermal maturity.
Although the organic matter in the studied intervals
are immature, exsudatinite, as secondary liptinite maceral, was observed in samples from the lower parts of the studied monitoring wells. Exsudatinite generally derives from the transformation of sporinite, alginite, resinite and varieties of
vitrinite, which is a resinous or asphalt like material. Considering the thickness and distribution of coal seams in the studied samples, it is unlikely the exsudatinite will be a major source for aquifer hydrocarbon contamination in the study area.
Additional stratigraphic studies and molecular geochemical analysis could provide an estimate of the total volume of possible organic compounds contribution to the aquifer in the study area. Due to the presence of coal seams in the studied intervals
of the Paskapoo Formation, it is important to investigate the possibility of biogenic methane formation in Paskapoo shallow aquifers. |
| Summary | (Plain Language Summary, not published)
This study is part of a larger study on the potential environmental impact of unconventional hydrocarbon development in the Fox Creek area in Alberta on
shallow aquifers. In addition to underlying organic-rich source rocks in the study area, the Paskapoo Formation contains organic-rich intervals and coal seams. In order to investigate any potential internal hydrocarbon source within the Paskapoo
Formation, nighty seven cutting samples from the formation obtained from eight shallow boreholes in the study area are studied to measure total organic carbon (TOC) content, organic matter composition, and thermal maturity of coal seams within the
Paskapoo Formation using programmed pyrolysis analysis and organic petrography. |
| GEOSCAN ID | 330296 |
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