Azimuthal AVO inversion of an elliptic orthorhombic medium
Bibliographic record
Abstract
Abstract Anisotropic information regarding the subsurface is important for various geophysical applications, including fracture characterization and estimation of the in situ stress field. Conventional techniques used to invert seismic amplitudes for anisotropic parameters estimate quantities such as the anisotropic gradient, which is not easily interpretable due to the amalgamation of various elastic stiffness coefficients. To gain an improved understanding of the anisotropic parameters estimated from azimuthal amplitude variation with offset (AVO) inversion, we simplify the PP reflection coefficient for a medium with arbitrary anisotropy by imposing an elliptic orthorhombic constraint. This results in a reduced form of the reflection coefficient in which the azimuthally dependent components are only a function of the horizontal P- and vertical S-wave velocities in a rotated coordinate frame. Furthermore, the anisotropic components are parameterized as direct perturbations from the isotropic solution, which requires no a priori information regarding the anisotropy and stabilizes the inversion. We demonstrate the utility of the elliptic orthorhombic approximation through an example in the Montney tight-gas play in northeast British Columbia, Canada, where we perform an azimuthal AVO inversion and estimate the crack density and differential stress ratio.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 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".