Evaluation of Natural Gas-Hydrate Systems Using Borehole Logs
Bibliographic record
Abstract
Introduction Background Natural gas hydrate, a clathrate in which water molecules form a cage around a single molecule of natural gas, is found in two settings in the subsurface: in permafrost regions on land and along continental margins offshore. Gas hydrate is restricted to shallow depths in both environments, with permafrost hydrate found in an interval up to ∼1000 m below the surface, and marine hydrate occurring up to several hundred meters below the seafloor mbsf). Compared with typical hydrocarbon reservoirs, the hydrate bearing host formations are relatively uncompacted and unconsoli-dated, and temperatures and pore water salinities are low. Natural gas hydrate is also unstable at surface temperature and pressure, making it difficult to study under laboratory conditions. Therefore, in situ measurements are a vital source of information about its properties. Borehole geophysical logs provide direct, depth-continuous measurements of gas-hydrate properties with a minimum of disturbance to the natural system. Commonly used log indicators of in situ gas hydrate are elevated electrical resistivity, high acoustic velocity, and anomalously low magnetic resonance porosity Mathews, 1986; Collett, 1993; Goldberg, 1997; Collett and Ladd, 2000; Guerin and Goldberg, 2002; Kleinberg et al., 2005; Murray et al., 2006). Borehole logs provide robust information about complex mixed natural systems containing pore and fracture filling hydrate, sediment grains, water, and free gas. Natural systems do not typically produce massive crystalline hydrate deposits.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".