Field Evidence for Rock Bridges Constricting the Opening of Fluid-Driven Cracks
Bibliographic record
Abstract
A field experiment in the Western Canadian Sedimentary Basin, Alberta, Canada entails creation of a horizontal subsurface lens (fluid-driven fracture) through fluid injection from a vertical well. The initial lens creation is followed by cycling of smaller injection and flowback stages. After completion of these smaller injection/flowback cycles, the lens is (presumably) expanded through a larger scale injection followed by another series of smaller injection/flowback cycles. Tiltmeter data indicates subhorizontal lens orientation and nearly circular shape. Combining the lens radius inferred from tiltmeter inversion with measurements of downhole pressure and downhole caliper width (opening) measurements indicate the compliance is far below the linear elastic fracture prediction based on assumption that the parting between the fracture surfaces is complete and no intact rock bridges constrain opening of the lens. Additionally, the compliance is shown to increase with increasing maximum width attained by the lens. This history-dependence suggests intact rock bridges are progressively broken as larger injected volumes are used to attain larger widths. In this view, as the bridges break, the lens compliance increases. By considering a model wherein bridges are accounted for by springs with a prescribed ultimate breaking length, the observed crack compliance and dependence of the compliance on the width history are matched. Hence, the detailed field data combined with a suitable bridge constriction model comprises compelling evidence for rock bridges constricting fluid-driven crack apertures at field scale. Acknowledgements. AB, AD and EP acknowledge support from the Australian Research Council through project DP190103260.
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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 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| 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".