Wellbore Integrity and Drilling Risk Evaluation During Depressurization in Gas Hydrate-Bearing Reservoir (GHBR)
Bibliographic record
Abstract
Abstract Wellbore integrity in gas hydrate-bearing formations is an important issue during drilling and production. Excessive pore pressure increase and formation strength reduction may occur during a wellbore a depressurization, the most popular and economic approach for hydrate production. Dynamic thermally induced hydraulic-mechanical (HM) effects may be triggered due to the solid hydrate decompositional process once the supercritical pressure is exceeded, despite an isothermal operation condition is maintained. A comprehensive model is developed to incorporate the phase change, porosity increase, and formation-weakening due to the hydrate decomposition process triggered once a critical equilibrium pressure or temperature is surpassed during a wellbore depressurization or heating. A thermal-hydraulic-mechanical-decompositional hydrate (THMD) model is proposed and a poro-elastoplastic model is imposed, in which a linear Mohr-Coulomb (M-C) criterion is introduced to characterize plastic deformation. The onset of wellbore integrity loss is assumed to occur if an equivalent plastic strain (EPS) exceeds a critical strain measured from experiments. The peak unconfined compression strengths (UCS), depending on the solid hydrate saturation and collected from several GHBR fields in the world, is assumed to dictate the critical EPS. The onset of wellbore collapse are calculated theoretically and validated by experimental hollow cylinder tests subject to isothermal condition. The critical wellbore pressure and temperature are calculated, the solid hydration saturation effects on formation cohesion, the onset and applications of wellbore integrity risk during wellbore depressurization are highlighted.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".