Fluid evolution in deeply buried and karstified carbonate reservoirs of the central Tarim Basin, northwestern China
Bibliographic record
Abstract
Abstract The Middle–Lower Ordovician Yingshan Formation is an important reservoir unit in the Tazhong oil field (Tarim Basin, northwestern China). This oil field is deeply buried (>5500 m [>18,045 ft]) and has endured a complex diagenetic history. To understand the mechanisms of reservoir formation, we conduct a broad portfolio of geochemical analyses on the calcite cements that fill the pores and fractures in samples retrieved from wells penetrating the Yingshan Formation. Our results identify six diagenetic episodes, each associated with the emplacement of different cements, varying from marine conditions (C1), near-surface to shallow burial (C2), intermediate-to-deep burial (C3 and C4), and infiltration of the formation with mixing of the underlying basinal brines with meteoric waters and hydrothermal fluids (C5 and C6) along northeast-trending strike-slip faults. The productive wells display evidence of a strong burial diagenetic overprint linked to exotic fluids (C5 and C6) along fractures. We conclude that eogenetic meteoric waters were vital in producing early diagenetic porosity within the Tazhong reservoir, which was subsequently refined by late burial (hypogenic) diagenetic processes. We anticipate our findings hold lessons for the evolution of other geodynamically active cratonic basins.
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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 | 0.001 |
| 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 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".