Laboratory Measurements and Numerical Simulation of Cyclic Solvent Stimulation with a Thermally Aided Solvent Retrieval Phase in the Presence of Wormholes after Cold Heavy Oil Production with Sand
Bibliographic record
Abstract
In this study, an experimental setup consisting of a sand pack with different configurations of complexity of wormhole patterns was designed. These different configurations have the same wormhole coverage index (WCI) determined by our earlier field-scale history match studies. After saturation of the model with heavy oil, three different solvents (CO 2, heptane, and diluents) were introduced into the wormhole structure inside the sand pack (injection phase) and then left for a period of time (soaking phase). Next, the resulted mixture (solvent and oil) was allowed to be produced (production phase). The experiment was aimed to mimic cyclic solvent stimulation at reservoir conditions, and several cycles were run for each experiment. At each cycle, the amount of collected oil and solvent was determined, and the resulting mixture was analyzed through gas chromatography and refractometry. It was observed that some of the injected solvent was trapped inside the sand pack. Therefore, in the final step, a solvent retrieval attempt was made by injecting different low-temperature hot water based on the solvent type. The aim was to observe how much additional solvent could be retrieved from the sand pack at reservoir conditions. Next, the sand-pack experiments were numerically simulated, and effective diffusion coefficients were obtained through history matching. To generate accurate predictions in field-scale simulation, an upscaling procedure from laboratory results of the cyclic solvent injection process was suggested. In this study, we observed that the use of light solvents (CO 2 ) could maintain the sand-pack pressure for a longer period (attributed to foamy oil phenomenon) compared to liquid solvent during the production phase. However, the oil recovery from sole application of light solvent was not as considerable as with the heavier solvents of heptane and diluents. These observations suggest that an improved heavy oil recovery could be achieved using a hybrid application of solvents and hot water in cold heavy oil production with sand (CHOPS) reservoirs. A post-flush hot water was found to play a positive role in solvent retrieval; however, the scale dependency of solvent retrieval behavior needs to be investigated. The findings of this paper can be used in a later study to optimize the field-scale solvent injection schemes considering the economics of the process tested.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 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) | 0.001 | 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".