A Coupled Reservoir-Geomechanics Model and Applications to Wellbore Stability and Sand Prediction
Bibliographic record
Abstract
Abstract Sand production and open hole collapse during production have been a great concern for production engineer, as the detrimental consequences are often associated to a desirable high production. Sand production usually occurs under a high-pressure gradient in poorly cemented formations. Whereas wellbore collapses could occur if a bottom hole pressure is below a certain level or production reaches a certain rate, i.e. during underbalanced drilling, under a high rate production, or when an aggressive well completion for high production is used. To determine the critical flow rate or bottom hole pressure, a coupled reservoir-geomechanics model is developed to simulate the interaction between reservoir flow and deformation. The model is developed and implemented numerically in Finite Element method by fully coupling a comprehensive geomechanics model to a three-phase reservoir behavior model. Gas component behavior is only considered below a bubble point, and it remains inside the oil phase before a critical gas saturation can be reached in our simulations. The effects of multiphase behavior on near well stresses and deformations, including high compressible gas component in the solution gas phase (foamy oil) are analyzed. Both Mohr-Coulomb and Drucker-Prager criteria are introduced to outline the plastic yielding surface and to govern the plastic flow. The effects of the stress-dependent formation moduli and permeability changes are permissible. The final stability and the onset of sand production are determined by a critical effective plastic strain and zero effective radial stress, whichever condition occurs first. Our studies indicate that, other than the well known factors such as bottomhole pressure and drawdonw, well stability and sanding risks are critically controlled by (1) the solution-gas behavior, (2) the formation stiffness, and (3) the residual cohesion. The latter can be senstitive to the wetting phase saturation. Considering production enhancement and formation damage, the reservoir porosity increase due to formation dilation is simulated, which can generate a negative skin near a well and result in a production enhancement. Our model can be used to calculate both the enhanced production and the ranges of the enhanced zone.
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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".