Comparative study between Kuster-Toksoz and differential effective medium method for determining pore type in carbonate reservoir

Characterizing or understanding carbonate rocks is always challenging. This is because carbonate rocks have a complex pore system due to their diagenesis process which is very intense. The diagenesis process causes changes in the mineralogy and the texture of the original frame which make a variety in pore types within carbonate rocks. Carbonate's pore system affects propagation wave velocity, so that seismic responses in carbonate rocks are poorly understood. Pore types of carbonate rocks could be determined by rock physics methods such as Kuster-Toksoz and Differential Effective Medium (DEM). Both methods generate some physical parameters models of the bulk and shear moduli of rocks. The input parameters are bulk and shear moduli of matrix and inclusion, geometry factor and fraction of inclusion. After performing both methods, effective bulk and shear moduli are extracted and the rock's pore type could also be determined by each method. Even though both methods have a similar function, they have a different way to generate the effective bulk and the shear moduli. The Kuster-Toksoz method focuses on the final condition of the rocks while the DEM method pays attention to not only the final condition, but also the process of how the rocks are (reached their final conditioned) formed. Then, the results of both methods are compared and controlled by well data. Based on that comparison, the DEM method is the one that has a higher coefficient correlation of pressure and shear wave velocity than the Kuster-Toksoz method. As a result, the DEM method is considered as a more suitable method for carbonate rock in determining the pore type of carbonate rocks and predicting their shear wave velocity.