Macroscopic Recovery Mechanisms of In-Situ Combustion Process in Heavy Oil Fractured Systems: Effect of Fractures Geometrical Properties and Operational Parameters
Bibliographic record
Abstract
Abstract The In-Situ Combustion (ISC) as a thermal EOR process has been studied deeply in heavy oil reservoirs and is a promising method for certain non-fractured sandstones. However, its feasibility in fractured carbonates remained questionable. The aim of the present work was to understand the recovery mechanisms of ISC in fractured models and to evaluate the effect of fractures geometrical properties such as orientation, density, location and networking on the ISC recovery performance. Combustion parameters of a fractured low permeable carbonate heavy oil reservoir in Middle East called KEM; applied to simulation study. Simulator has been validated with KEM combustion tube experimental data and validated model modified to 3D semi-scaled combustion cells. It was found that in fractured models oxygen first flows into the fractures and then diffuses from all sides into the matrix. Combustion of the oil in the fractures produces water ahead of fracture combustion front which prohibits oxygen from early breakthrough through fractures into producer. Water imbibes into matrix and causes further oil drainage. Part of this oil imbibes into downstream matrices and the other part produces into producer through fractures. The oxygen diffusion/water imbibition based recovery mechanism is slower in production rates compare to conventional model recovery mechanism, and also results in lower quality of produced oil. It was found that ISC recovery was higher in the presence of networked fractures (presence of both longitudinal and traversal fissures) compare to the case of presence of either longitudinal or traversal fracture systems. Results show that ISC is more feasible in the case of densely fractured reservoirs such as those in the Middle East. Further, sensitivity analysis on air injection rate, formation thickness, injection well depth of perforation and also feasibility of water alternating gas (air), WAG, process for fracture model have been studied.
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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 | 0.000 | 0.000 |
| 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) | 0.000 | 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".