Investigation of Post-Abandonment Surface Deformation in SAGD Operations
Bibliographic record
Abstract
Abstract Steam-Assisted-Gravity-Drainage (SAGD) has been extensively applied in thermal recovery from oilsands reservoirs in the Athabasca region of Northern Alberta. As the steam chambers associated with SAGD well pairs become mature, a form of abandonment is often applied for pressure maintenance in the depleted zone. Quantification of potential surface subsidence associated with SAGD abandonment becomes critical especially when the mature wells are in proximity of future developments. In addition, induced shear stresses should also be estimated to fulfill well integrity requirements. In this case study, a coupled reservoir – geomechanical simulation model is developed, calibrated and utilized to estimate the magnitude of post-abandonment subsidence and the induced shear stresses in Surmont SAGD Pilot Project. In the context of this study, first, the development of a simplified 2D static geomechanical model using an original geomodel realization as well as geomechanical properties and stress profiles is discussed, which forms the basis for the coupled simulation model. The calibration workflow of the coupled reservoir-geomechanical simulation model to historical heave data is then reviewed and the impacts of different parameters on calibration quality is investigated. Finally, the estimation of subsidence and the induced shear stresses in the nearby wells is discussed, and the magnitude of residual heave is quantified. The results of this study show that only a fraction (up to 40%) of surface heave is reversible (in form of subsidence) during the abandonment phase. Therefore, the magnitude of the surface subsidence and the associated shear stresses are quite small. The modeling study has also shown that a small magnitude of subsidence may be recorded even 10 years after abandonment. However, more than 50% of the surface subsidence is observed in the first two years post-abandonment. Other important findings of this study includes (1) documenting the effects of thief zone interaction as it relates to irreversibility of surface heave; (2) documenting the impacts of various geomechanical parameters on the quality of calibration against the historical heave data; (3) observation of the relative impacts of the pressure and temperature fields on the magnitude of heave; and (4) quantification of incremental, yet small, shear stresses along the nearby horizontal wells.
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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".