| Title | Molecular and stable carbon isotope geochemistry of mud-gas-derived hydrocarbons and its application for the assessment of low-permeability reservoirs from the Montney Formation, Western Canada |
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| Author | Cesar, J ; Mayer,
B; Becker, V; Nightingale, M; Ardakani, O H |
| Source | Organic Geochemistry vol. 163, 104328, 2021 p. 1-7, https://doi.org/10.1016/j.orggeochem.2021.104328  Open Access |
| Links | Online - En ligne
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| Image |  |
| Year | 2021 |
| Alt Series | Natural Resources Canada, Contribution Series 20210399 |
| Publisher | Elsevier |
| Publisher | GeoConvention Partnership |
| Document | serial |
| Lang. | English |
| Media | digital; on-line |
| File format | pdf; html |
| Province | British Columbia |
| NTS | 93I; 93O; 93P; 94A; 94B; 94G; 94H; 94I; 94J |
| Area | Fort St. John; Canada |
| Lat/Long WENS | -123.0000 -120.0000 58.2500 54.5000 |
| Subjects | fossil fuels; stratigraphy; geochemistry; sedimentology; Science and Technology; Nature and Environment; petroleum resources; hydrocarbons; hydrocarbon migration; stable isotope studies; carbon
isotopes; petrographic analyses; stratigraphic analyses; core samples; pyrolysis; chromatography; mass spectrometer analysis; Montney Formation |
| Illustrations | cross-plots |
| Program | Geoscience for New Energy Supply (GNES) Shale Reservoir Characterization |
| Released | 2021 10 08 |
| Abstract | Mud-gas isotope logging (MGIL) of hydrocarbons (methane, ethane, propane) has become a widely used approach to fingerprint gas-bearing formations during the drilling of vertical and horizontal oil and
gas wells often with the goal to assess potential cross-formational gas migration. In this study, we have used mud-gas molecular and isotope data to assess the usefulness of MGIL for the geochemical assessment of a single low-permeability reservoir
formation, the Montney Formation in Western Canada. An example from a well completed in British Columbia shows that hydrocarbon samples collected in IsoJars® tend towards more positive carbon isotope ratios compared to data for samples obtained using
IsoTubes®, potentially attributed to 13C enriched residual gas retained in the cuttings. Additionally, in publically available mud-gas data from 45 other wells, it was found that the carbon isotope ratios of mud-gas from the Montney Formation are
overall consistent with the thermal maturity of this stratigraphic unit, but the data display a relatively scattered trend on a thermal maturity plot based on D13CC1-C2 and D13CC1-C3. Molecular parameters such as [C1/(C2 + C3)] can be modified via
processes such as desorption and diffusion after sampling gases in IsoJars®, while the i-C4/n-C4 ratio was found to be the most consistent molecular parameter between sampling techniques. We conclude that mud-gas molecular and isotope data derived
from samples collected in IsoTubes® are suitable for geochemical assessment (e.g. thermal maturity, fluid-fluid correlations) of low permeability hydrocarbon reservoirs such as the Montney Formation. |
| Summary | (Plain Language Summary, not published)
In this study, we have used mud-gas molecular and isotope data to exemplify the limitations of mud-gas isotope logging (MGIL) for geochemical assessment
of the Montney Formation low-permeability reservoirs. The caveats derive from isotopic fractionation, and more drastically, chemical fractionation that can be attribute to different sampling techniques. Although MGIL may have localized monitoring
applications during drilling, we do not recommend their usage to establish robust geochemical interpretations unless other geochemical variables are well stablished. |
| GEOSCAN ID | 329225 |
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