Caprock Integrity Case Study for Non-thermal Polymer Flooding Project Using 4D Reservoir Coupled Geomechanical Simulation
Bibliographic record
Abstract
Abstract Maintaining an effective caprock seal is of prime importance in any enhanced oil recovery (EOR) stimulation involving subsurface injection of fluid. Hydraulic or mechanical breaching of the caprock may entail leakage of injected fluids and/or hydrocarbons into shallower formations, or even to the surface, with the potential for adverse environmental impact. Determining a safe optimal injection pressure which minimizes the likelihood of such an occurrence is a challenging problem. For example, assessing caprock integrity with the static stress measurement alone at the virgin state of reservoir without considering dynamic stress changes is likely to be both unreliable and inadequate. In this paper, we present a case study of hydraulic and mechanical integrity of Wabiskaw caprock at multiple injection scenarios under dynamic conditions. In this study a multi-disciplinary approach was used which integrates geology, petrophysics, reservoir engineering and geomechanics followed by a finite element coupled reservoir-geomechanics simulation. A 3-D mechanical earth model (MEM) was constructed utilizing advanced azimuthal shear anisotropic sonic log and core based mechanical properties. All the available LOT mini-frac as well as MDT micro-frac tests data were assessed and used to calibrate the anisotropic stresses at initialization step in addition to assessing the lateral variability of the vertical stress. Several tight streaks expected to provide additional abutment to the primary caprock were honored in the model. The 3-D MEM was extended to the surface and embedded with the sideburden and underburden layers incorporating adjacent injectors and producers to minimize the boundary effects. This study evaluated tensile and shear failures within the reservoir and the caprock at several injection scenarios for a period of 30yrs with injection bottomhole pressures of 116 and 155bar at the rate of 150 m3/day. No shear failure or tensile failures were predicted by the coupled geomechanical simulator in the caprock for all the injection scenarios. This model also predicted the vertical displacement within the reservoir, caprock and at the surface. The amount of heave at the ground surface was negligible.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".