Stable Isotope and Geochemical Investigations into the Hydrogeology and Biogeochemistry of Oil Sands Reservoir Systems in Northeastern Alberta, Canada
Bibliographic record
Abstract
The objective of this thesis was to provide insight into the hydrogeology and biogeochemistry of the heavily biodegraded bitumen reservoirs of the Athabasca oil sands region of Alberta, Canada, using applications of aqueous and stable isotope geochemistry. Published data were used to generate a regional map of total dissolved solids concentrations in McMurray Formation waters. To explain the regional salinity data, a revised hydrogeological model was developed that incorporates localized upward flow of formation waters from saline Devonian aquifers into the bitumen-bearing McMurray Formation via karst-derived conduits. Where McMurray Formation waters are uninfluenced by connectivity with Devonian aquifers, topographic recharge from meteoric water is the dominant hydrogeological process. A new method was developed to determine the stable isotope composition and salinity of McMurray Formation waters from porewater samples extracted from drilling fluid-contaminated core. Mixing relationships of δ2H and δ18O values in drilling fluid and formation water were used to calculate the original formation water stable isotope composition and salinity from porewater extracted directly from oil sands drill core. Both vertical and lateral heterogeneity were observed on a reservoir-scale, and topographically-derived groundwater recharge was determined to be the dominant hydrogeological process in Suncor-Firebag lease area. Biogeochemical aspects of oil sands systems were investigated in two studies. The first study examined the impact of variable aqueous geochemistry on oil sands biogeochemistry, specifically methanogenesis and bacterial sulfate reduction, in laboratory-scale microcosms. Changes in aqueous geochemistry induced changes in the total amount of methane generated, and in the stable isotope ratios of carbon and hydrogen of generated methane. The second experiment measured natural abundance radiocarbon in dissolved inorganic carbon in a coal-bed methane reservoir in the Powder River Basin, Montana, USA. All samples of dissolved inorganic carbon and methane contained no detectable radiocarbon, and thus the carbon flux from biodegradation of coal was much greater than the carbon flux from recent groundwater recharge into the coal-bed aquifer system. Improved understanding of hydrogeological processes, and better understanding of reservoir biogeochemistry will lead to better decision making by industry and regulators during the development of oil sands resources, while our society transitions away from fossil energy over the coming century.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".