Simulation of Tectonic Deformation and Large-Area Casing Shear Mechanisms—Part A: Operations
Bibliographic record
Abstract
Abstract We present an analysis of casing deformation mechanisms in one area of extensive casing shear in the Daqing Oilfield, China. Instead of qualitatively stating the cause of large areas of casing shear, as in most previous work, we developed a mathematical model to quantitatively compute the coupled effect between the tectonic stress field and the induced stresses from high-pressure water injection. Numerical simulation carried out in the area indicated that variation of injection pressure induced a substantial perturbation on the local stress field. Furthermore, the induced stress fields associated with each injection well overlap with each other. Once the maximum compressive stress parallels or nearly parallels the differential pressure, the stability of strata with respect to shear is compromised, and when the thrust stress imposed exceeds the shearing resistance, the strata will slip in a direction coaxial with the vector from high to low-pressure areas. Simulation results of various schemes show that as long as the injection pressure and pressure differential between blocks are controlled to be less than 12.7 MPa and 0.86 MPa respectively, formation shear slip along a horizontal surface will no longer occur. The study in this article is somewhat different from previous studies in that a full coupling of the in situ and the induced stress fields was performed quantitatively and based on field experiments, and also in that the results were used to explicitly determine pressure limits on individual wells and differential pressures for the entire region of casing shear. The method and the results can serve as reference for other similar oilfield circumstances.
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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) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| 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".