A support vector machine algorithm to classify lithofacies and model permeability in heterogeneous reservoirs
Bibliographic record
Abstract
Porosity, permeability, and fluid saturation distributions are critical for reservoir characterization, reserves estimation, and production forecasting. Classification of well-log responses into separate electrofacies that can be used to generate local permeability models gives means to predict the spatial distribution of permeability in heterogeneous reservoirs. Recently, support vector machines (SVMs) based on the statistical learning theory have been proposed as a new intelligence technique for both regression and classification tasks. The formulation of support vector machines embodies the structural risk minimization (SRM) principle which has been shown to be superior to the traditional empirical risk minimization (ERM) principle employed by neural networks. SRM minimizes an upper bound on expected risk as opposed to ERM that minimizes the error on the training data. It is this difference which equips SVM with a greater ability to generalize to new wells. Here, a nonlinear SVM technique is applied in a highly heterogeneous sandstone reservoir to classify electrofacies and predict permeability distributions. The SVM classifier is compared to discriminant analysis and probabilistic neural networks. SVM predictions of the permeability are compared to that of a back-propagation and general regression neural networks. Statistical error analysis shows that the SVM method yields comparable or superior classification of the lithology and estimates of the permeability than the neural network methods. A comparison of log-based and core-based clustering reveals that permeability prediction based on core-based clustering were slightly better than that of the log-based clustering.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".