Abnormal pressure genesis and its relationship with continental shale oil accumulation in Paleogene, Jiyang Depression, Bohai Bay Basin
Bibliographic record
Abstract
In order to explore the effect of abnormal pressure on shale oil accumulation in the Jiyang Depression, Bohai Bay Basin, the formation pressure distribution, muddy shale lithofacies, hydrocarbon generation evolution of organic matters, clay mineral conversion, hydrocarbon retention, and the distribution of secondary pores and microfractures in each of four exploration wells specially for Paleogene shale oil were studied by total rock X-ray diffraction analysis, conventional pyrolysis analysis on hydrocarbon generation potential, systematic analysis on organic geochemistry, and other methods. In the study area, the lithofacies association in middle and lower submembers of the third member (Es3middle and Eslower)3, and upper submember of the fourth member (Es4upper) of Paleogene Shahejie Formation adjacent to subsag center is mainly carbonate rocks, while near sag margin, there are primarily mixed sediments of clastic rocks/chemical rocks. Based on the data from sonic, density and drilling loggings, pressure distribution and abnormal pressure characteristics in single well could be identified effectively; in addition, the factors that affect formation pore pressure in organic shale containing major association of carbonate and clay minerals could be uncovered. Comprehensive application of geochemical evidences confirmed that Paleogene overpressure in the Jiyang Depression was mainly originated from hydrocarbon generation pressurization in mature muddy shale. Self-source overpressure intervals in muddy shale are in correspondence with the zones of secondary pore development and peak hydrocarbon retention.
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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 | 0.001 | 0.001 |
| 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) | 0.000 | 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 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".