Integration of Petrophysical Methods in Carbonates from the Potiguar Basin: Technical Complementarity and Multivariate Analysis

Abstract

This study presents an integrated analysis of three petrophysical techniques: gas porosimetry, water immersion saturation, and nuclear magnetic resonance (NMR), applied to 89 carbonate rock samples from the Potiguar Basin, within the Grainstone, Dolowackstone, and Bioturbated lithofacies. Descriptive statistics, Pearson correlations, analysis of variance (ANOVA) with Tukey’s test, and principal component analysis (PCA) were performed to evaluate complementarity and variability among methods. The Technical Complementarity Index (TCI) was 0.948, indicating high overall agreement, with the greatest similarity observed between NMR and gas porosimetry (0.963). Saturation systematically underestimated porosity, particularly in microporous rocks. ANOVA revealed significant differences (p < 0.001) among lithofacies, with Grainstone showing the highest average porosity. PCA demonstrated that the first principal component (PC1) explains 96.5% of the total variance, with factor loadings above 0.98 for all methods, confirming that they essentially measure the same fundamental physical attribute, albeit with different sensitivities. The results highlight that statistical and multivariate integration reduces uncertainties and improves petrophysical characterization of heterogeneous carbonates, with direct implications for fluid volume estimation.