Experimental Investigation of In-Situ Combustion at Low Air Fluxes
Bibliographic record
Abstract
Summary The oil industry has inherited a mixed history of success and failure of application of air injection as an enhanced-oil-recovery method. Close scrutiny of these projects shows that in order to conduct a successful in-situ-combustion-oil-recovery project, sustained propagation of the combustion front within the reservoirs is necessary. Sufficient air must be supplied to maintain the propagating combustion front in the desired bond-scission (carbon-oxide-forming) mode, otherwise unfavourable oxygen addition [i.e., low-temperature-oxidation (LTO) reactions] will consume oxygen and immobilize oil. When this happens, the combustion process is deemed to be exhausted. Quantification of the minimum air flux required for sustaining combustion-zone propagation is needed to properly match the capacity of the air-injection facility to the volume of the reservoir that is to be swept by the thermal zone. Undersizing the air-injection capacity causes the in-situ-combustion process to become inefficient at a point when only a small portion of the reservoir has been "burned." One-dimensional combustion tubes (CTs) are conventionally used to obtain important combustion parameters required for designing an air-injection project. Because of the high heat capacity of laboratory equipment designed for elevated-temperature and -pressure operation, oxygen addition or LTO reactions are promoted by the heat transfer through the core-holder walls when the laboratory tests are performed at low air-injection rates. Therefore, when operated at elevated pressures, the CTs are unable to operate at the low air fluxes required to establish the minimum possible air-injection flux while maintaining the combustion reactions in an effective mode. To address this issue, a state-of-the-art combustion cell was conceived and used as a way of addressing the previously mentioned constraints associated with high-pressure 1D CTs. A conical combustion-cell design was built because it enables continuous air-flux reductions without having to adjust the air-injection rate. The heater control strategy was also modified in order to address the lag-lead operation often used for 1D CTs. To date, the unit has operated at air fluxes down to 3 std m3/m2•h. The experimental work described in this paper provides insight into the limitations in laboratory investigations of in-situ combustion and the expected behaviour of field applications of the in-situ-combustion process.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".