Risk Analysis on Geological and Geomechanical Uncertainties - Learnings from CO2 Sequestration Modelling of a Saline Aquifer in Central Alberta, Canada
Bibliographic record
Abstract
Abstract The Government of Alberta has entered into evaluation agreements with 25 hubs to investigate permanent CO2 sequestration options, including deep saline aquifers. There is a rush of optimistic claims from numerous organizations on how much CO2 they are planning to dispose, yet it remains unclear how this will be achieved. In this study, practical models were constructed for the Basal Cambrian Sandstone (BCS) to evaluate its CO2 storage capacity from regulatory, geological and geomechanical perspectives. Field data was collected from the Quest carbon capture and sequestration (CCS) facility, operated since 2015. A geomechanics module, integrated with a dual-permeability fluid model, was utilized to investigate the input variables of the storage formation and associated caprock, such as permeability, Young's modulus, Poisson's ratio, and Biot coefficient, etc. Barton-Brandis model was adopted to investigate CO2 leakage paths through natural fractures in the caprock. An extensive history match was performed and forecast cases were conducted to assess CO2 plume migration, trapping mechanisms, and pressure distribution throughout the life span of the project and over one hundred years after shut-in of CO2 injection. The results have shown that the amount of CO2 disposal could be over four times the original designed capacity if the injection wells can be operated at maximized injection rate while still maintaining injection pressure below the regulated pressure limit. In addition, the CO2 storage potential can be significantly impacted by geological and geomechanical uncertainties, including ambiguities in structural and petrophysical interpretations, characterization of natural fractures, etc. For example, injection pressure that is higher than the minimal effective stress could lead to failure in the caprock. The changes of natural fracture permeabilities are modelled with the effective stress of surrounding rock matrix and the extent of CO2 leakage into the caprock is studied. The results showed that when reactivated, the natural fractures, especially those near the injectors, substantially increased the amount of CO2 leakage into the caprock. When this happens, it could potentially impose a risk to both storage capacity and safe containment of the sequestered CO2. Finally, proxy functions were developed for correlating the calculated CO2 storage capacity and risk factors. This provides a simplified analytical approach for further risk mitigation. This study performed a comprehensive quantification of regulatory, geological, and geomechanical risks in a CCS project with real-world data. It provides an exemplary workflow of risk assessment, both numerically and analytically, to guide exploration, planning, operations, and monitoring of future CCS projects.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".