A Review of Tracers in Monitoring CO 2Breakthrough
Bibliographic record
Abstract
Abstract Tracers can be added to the injected CO 2stream in geosequestration projects to demonstrate safety and containment to stakeholders by verifying the presence of injected CO 2(other CO 2may exist), monitoring the possible leakage of CO 2(fingerprinting tool), and measuring the behavior of CO 2under injection (e.g., saturation, fluid mixing, calibrating models, etc.). Monitoring may be required in a variety of settings (e.g., reservoir fluids, shallow groundwater, deep soil, surface emissions, and formation gases). Thus, an appropriate tracer or suite of tracers is required for clear identification if the CO 2migrates out of the injection zone. Although the injected CO 2in some study areas has been isotopically distinct from the existing CO 2present in the aquifer or reservoir (e.g., the Encana Enhanced Oil Recovery Program at Weyburn, Saskatchewan, Canada), this is not always the case. Tracers are required to be chemically inert, environmentally safe, nontoxic, persistent, and stable for purposes of the desired monitoring time scale. Low-volume usage (for cost, availability, and ease of handling) and sensitivity to detection by analytical methods are also of key importance. Application methods (e.g., pulsed or continuous addition) may also affect costs. More commonly than not, the analytical costs are seen to be the most prohibitive cost overall (specialist tracers, very precise measurements by specialized methods or equipment, etc.). Based on the general requirements for carbon storage, several possible tracer compounds have been identified by various authors and summarized here. Their behavior, availability, ease of analysis, and indicative costs are evaluated. This list is by no means exhaustive for all likely tracers. The Cooperative Research Centre for Greenhouse Gas Technologies (CO 2CRC) is conducting a CO 2storage pilot program in Victoria, Australia. The Otway Project site is a depleted natural gas reservoir with roughly 20% residual methane saturation and a remaining methane-rich gas cap. In addition, the natural source of CO 2for injection is mixed with about 20% methane content. Thus, tracers are required that may give information on the fate of the injected CO 2-methane combination. Some preliminary work on CD 4(fully deuterated methane) is presented, and further work on the evaluation of this potential tracer is discussed.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".