Reexamination of controlled-source electromagnetic inversion at the Lona prospect, Orphan Basin, Canada
Bibliographic record
Abstract
ABSTRACT In 2010, an exploration well was drilled at the Lona prospect in the Orphan Basin, Canada, whose location was based primarily on a structural high at the base of a Cretaceous unconformity. Additionally, a 3D inversion of controlled-source electromagnetic (CSEM) data collected in 2007 and 2009 indicated elevated resistivities that roughly correlated with the structural high, indicating the possibility of hydrocarbon-saturated sediments. The well did not encounter hydrocarbons, and the results were considered a false positive. In an effort to better understand the geologic significance of the elevated resistivity anomaly, we have reexamined the original interpretation of the Lona prospect by using a seismic image-guided inversion algorithm to analyze CSEM data from a synthetic model and the field data and correlate those results with lithology predictions from seismic amplitude versus angle inversions. We conclude that the anomalously high resistivities seen are due to the high volumes of cemented sand lithology and not to the presence of hydrocarbons. We speculate that if the results shown here had been available at the time, CSEM would not have provided support to the decision to drill.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".