Stratigraphy and Depositional Model of Palaeogene Dongying Braided-River Delta Sandstones, L Field, Bohai Bay Basin, Offshore Eastern China
Bibliographic record
Abstract
Fluid production of L field, Bohai Bay Basin, offshore eastern China is mainly from the Palaeogene Dongying D interval. The stratigraphy framework and depositional model of the braided-river delta system within the D interval are investigated using seismic, well log, core data and production response. The D interval is interpreted as having been deposited in a lowstand system tract. And two progradational successions are recognized, including in ascending order the D2 and D1. The younger sandstone in the D1 interval is of greater thickness and larger distribution area than the elder sandstone in the D2 interval. Six core facies and five log patterns are recognized and interpreted to be underwater distributary channels, levees, overbank splays, mouth bars, sheet sand and shalier interchannel deposits. Channel deposits occur along the trend of thickest D2 and D1 sandstones. The sandstones that flank each side of the channel deposits are interpreted to be levee and overbank splay deposits. The sandstones that develop at terminal distributary channel mouth are interpreted to be mouth bar and sheet sand deposits. Channel-flank deposits can form good-quality reservoir sandstones, but they contain interbedded siltstones and thus have lower porosity and permeability than do channel deposits. The facies distributions predicted for the D interval match trends of the daily total fluid production. Knowledge gained from study of the L field has application to the development of other fields with similar depositional and diagenetic histories.
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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) | 0.001 | 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".