<p>Flowchart of the procedure applied for developing simple and hybrid ML models to predict FV in DF from two easily measured input variables, FD and MFV.</p> Full article ">Figure 2
<p>Applying the GO algorithm to determine optimal hyperparameter values for the RBFNN predictor.</p> Full article ">Figure 3
<p>Flowchart illustrating the implementation of the MELM-GO hybrid ML model designed for predicting the FV properties of DFs.</p> Full article ">Figure 4
<p>Heatmap correlation matrix displaying the relationships between independent and dependent parameters for the compiled dataset.</p> Full article ">Figure 5
<p>RMSE results for the FV dataset evaluated with the RBFNN model with three training/testing subset separation ratios.</p> Full article ">Figure 6
<p>Identification of outliers in the FV training dataset using GPR–Mahalanobis distance (MD) modeling.</p> Full article ">Figure 7
<p>The iterative reduction of RMSE within various iterations of the GO algorithm is employed to ascertain the optimal structure of the MELM algorithm in the prediction of the FV.</p> Full article ">Figure 8
<p>Comparative cross-plots evaluating accuracy of measured and predicted FV values utilizing (<b>a</b>) MELM, (<b>b</b>) MELM-GO, (<b>c</b>) RBFNN, and (<b>d</b>) RBFNN-GO models on training data.</p> Full article ">Figure 8 Cont.
<p>Comparative cross-plots evaluating accuracy of measured and predicted FV values utilizing (<b>a</b>) MELM, (<b>b</b>) MELM-GO, (<b>c</b>) RBFNN, and (<b>d</b>) RBFNN-GO models on training data.</p> Full article ">Figure 9
<p>Assessment of the error convergence of GO algorithm iteration sequences for the two HML models configured to predict the FV.</p> Full article ">Figure 10
<p>Comparative cross-plot accuracy evaluations of measured and predicted FV values achieved by the trained (<b>a</b>) MELM, (<b>b</b>) MELM-GO, (<b>c</b>) RBFNN, and (<b>d</b>) RBFNN-GO models applied to the testing data subset.</p> Full article ">Figure 11
<p>Radar chart contrasting prediction scores achieved by standalone ML and HML models.</p> Full article ">Figure 12
<p>Relationships between the percentage of added noise to the input variable distributions and R<sup>2</sup> values for FV predictions for the ML and HML models.</p> Full article ">Figure 13
<p>Visualizing the effect of the two input features on the FV predictions with SHAP values for the RBFNN-GO model applied to the training subset: (<b>a</b>) SHAP detailed feature impact plot and (<b>b</b>) SHAP summary plot of the feature importance.</p> Full article ">Figure 14
<p>The (<b>a</b>) 3D and (<b>b</b>) 2D heat map partial dependence plots showcasing the interplay between pairs of input features in the predictions of the FV as generated by the RBFNN-GO model applied to the training subset.</p> Full article ">Figure 15
<p>Comparison of the measured FV values with those predicted by the RBFNN-GO model for the unseen data.</p> Full article ">Figure 16
<p>Workflow diagram demonstrating how the configured HML models can be applied in the DF well-site laboratory to assist the drilling crew with FV semi-real-time monitoring and decision making.</p> Full article ">