Evaluation of Gassmann and Patchy Saturation Models in Carbonates from an Oil Field in the Middle East

The applicability of rock physics models in carbonates is not well understood yet. The aim of this study is to carry out an evaluation of different rock physics models in carbonate rocks from an oil field in the Middle East. We evaluate three rock physics models including Gassmann, Patchy saturation and the Voigt approximation of Patchy model. We use well log data as well as lab measurements on dry samples to perform the evaluation. Our results reveal that while all tested models underestimate bulk modulus in general, Voigt approximation of Patchy model makes the best predictions. Moreover, we observe that the relative difference between the predicted and measured bulk modulus decreases as the rock heterogeneity decreases. We found that predictions of bulk modulus in homogenous rocks show good match with measured modulus.