Comparison of Rock Physics Models to Predict Rock Properties in Carbonate Reservoirs

Abstract

Summary In this core study, we show the similarities and difference of the two rock physics models. Our motivation is to determine which of the two models is (a) more robust to predict Vs velocities and (b) preferred to understand the rock’s pore structure. We revisit how a differential effective medium model and an thin section image analysis procedure is used to determine the rock’s pore structure (Baechle et al. 2008). Using a differential effective medium (DEM) model with a dual porosity approach, we predict velocity using macro- and microporosity as derived from thin section analysis. A conceptual aspect ratio of 0.1 for micropores and a measured aspect ratio of 0.5 for macropores results in the satisfying prediction of elastic properties of carbonate rocks. We compare the Dry Rock Approximation (DRA) (Keys and Xu, 2002) and the Extended Biot Theory (EBT) (Sun et al., 2000). Both methods are successful utilized to approximate the DEM velocity trend lines of two endmember aspect ratios for macropores and micropores. Low permeability rocks are uniquely identified by a high compressional coefficient (in EBT and DRA models) in our dataset, hereby emphasizing the potential of improved reservoir characterization using locally calibrated rock physics models