Analysis of Fracture Initiation Pressure of Horizontal Well at Anisotropic Formation Using Boundary Element Method
Bibliographic record
Abstract
With the influence of bedding plane, the mechanical properties of bedded rocks, such as shale and coal rock at vertical and parallel bedding direction show comparatively significant difference. Therefore, compared with homogeneous rocks, bedded rocks exhibit obvious anisotropic mechanical properties. Currently, most fracture initiation pressure prediction models simplify rock to homogeneous dielectric elastomer, which is inapplicable to calculate wellbore fracture initiation pressure at bedded stratums. Given that the mechanical properties of bedded rocks at bedding plane direction are the same, this paper established a calculation model of horizontal well fracture initiation pressure in the anisotropic formation and set up a numerical solution method of circumferential stress around the borehole by means of using boundary element method. In addition, a calculation method for fracture initiation pressure based on tensile strength criterion and simplex algorithm was also proposed. The research results indicate that: In the case of high elasticity modulus anisotropy ratio, the wellbore fracture initiation pressure is low; when the elasticity modulus at vertical bedding direction is greater than that at parallel bedding direction, fracture initiation pressure decreases with the increase of bedding dip angle; the shape of wellbore has imposed an significant influence on fracture initiation pressure. For non-circular wellbore, fracture initiation pressure increases with the increase of length-width ratio in the case of smaller ovality. When wellbore shape transforms from equiaxial circle to long and narrow ellipse, fracture initiation pressure decreases with the increase of stress concentration level. Thus, this paper performed calculation and comparison with classical solutions for particular cases similar to isotropic body of stratum using the model established which verified the validity of the proposed theory. According to the research results, a new method for precise calculation of fracture initiation pressure of horizontal well at bedded stratum was provided.
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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 | 0.001 |
| 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".