Clay Volume Calculation from Acoustic and Density Curves using the Gyllenhammar Equation
Bibliographic record
Abstract
Summary This case study demonstrates the calculation of clay volume in rock using density and acoustic logging, specifically in the northern oil and gas fields of the North Sea. The methodology is based on the Gyllenhammar formula and involves selecting appropriate coefficients for each analyzed interval. First, the clay volume should be calculated using gamma gay and/or a combination of neutron and density logs. Next, a cross-plot of density and acoustic logging is created, and the coefficients in the equation are determined from this plot. Finally, both clay volumes are compared, and if necessary, the coefficients in the equation are further calibrated. We can derive acoustic impedance from seismic data, calculated as the product of rock density and velocity. In this study, we modified the Gyllenhammar equation to create a formula for estimating clay content based on velocity and rock density. This approach demonstrates the ability to accurately calculate one of the essential parameters, such as clay volume, in the inter-well space using seismic data.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".