3D source-rock modelling in frontier basins: a case study from the Zambezi Delta Depression
Bibliographic record
Abstract
Regional modelling is vital for the preliminary analysis of a basin's hydrocarbon potential, especially when working on incomplete datasets. The Zambezi Delta Depression is a frontier basin that was selected to demonstrate how limited, publically available depth data can be used to evaluate source-rock maturity and hydrocarbon expulsion using 3D basin modelling. A geological framework was built with multiple datasets correlated using a global sequence-stratigraphic model. The identification of key events in the geological history of the region and the basin geometries allowed interpretation of intervals of organic enrichment within the basin during the Bajocian, Kimmeridgian and early Aptian. The results from the pressure and temperature modelling show that these potential source-rock horizons are currently overmature to gas mature in the Zambezi Delta Depression. Using the most likely heat-flow scenario, the timing of maturity and expulsion of the potential source rocks are strongly controlled by the geometry of the basin, with ages decreasing towards the SW. Expulsion modelling suggests that the Late Cretaceous plays are most likely to be charged by the early Aptian source rock, with older potential plays charged by the Jurassic source rocks. As the heat-flow model was poorly constrained, warmer and cooler temperature scenarios were also applied to qualitatively compare the impact on maturity, expulsion and accumulation of hydrocarbons in the basin. The modelling results, when compared with sparse published data, favour the most likely and warmer scenario. Supplementary material: Details of the model input data, source-rock definitions and software used in this project are available at https://doi.org/10.6084/m9.figshare.c.3970863
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".