The Change in Geomechanical Properties of Gas Saturated Methane Hydrate‐Bearing Sand Resulting From Water Saturation
Bibliographic record
Abstract
Abstract Laboratory tests were carried out on gas‐saturated hydrate‐bearing sand (HBS) specimens that were subsequently water saturated to determine the influence of water saturation on their small‐strain (stiffness) and large‐strain (strength) behavior. Hydrate formed using the “excess gas” method led to significant increases in stiffness and strength of the sand. The magnitude increase in stiffness was largest for the lowest hydrate saturation tests and was sensitive to the distribution of hydrate within the sand. In contrast, increases in strength were directly related to increases in hydrate saturation, and to a lesser extent, on the applied confining stresses. Subsequent water saturation of these gas‐saturated HBS (achieved by flushing up to three times the pore volume of water through the HBS specimen) led to ∼90% and ∼70% reduction in stiffness and strength, respectively, along with a 37% reduction in hydrate volume (initial hydrate pore saturation ∼21.5%). Specimens with higher initial hydrate saturations (∼48%) saw slightly smaller reductions in stiffness and strength associated with ∼17% reduction in hydrate saturation. Changes in behavior appear to be related to the reduction of “cementing” hydrate at particle contacts through dissociation/dissolution of the hydrate, with remaining hydrate being more “pore filling.” Processes that may induce fluid flow in a natural gas‐saturated HBS, such as during the depressurization of the HBS reservoir during hydrate production, may lead to changes in hydrate morphology and affect the geomechanical properties of the HBS even when the HBS are still under hydrate stability conditions.
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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 | 0.000 |
| 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 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".