Anisotropy in Stratified and Equivalent Media: Kinematic and Amplitude Analysis

Abstract

We implemented an elastic-anisotropic seismic modeling algorithm via synthetic models to evaluate different geological scenarios, where intercalations of sandstones and shales, carbonates and shales and halite and high-speed salt were simulated. These lithologies were selected based on their abundance in the sedimentary record and the importance they have in the composition of petroleum systems. We analyzed the results relative to kinematic and dynamic aspects to broaden the understanding of how these elements act in the presence of anisotropy. Additionally, the elastic and anisotropic parameters of intercalations composed by the referred lithologies were analytically estimated, thus obtaining the characteristics of several equivalent media. The results confirm previous postulations that the intercalation of layers with different properties can generate extrinsic anisotropy, contributing to the perspective of different wavelength(λ)/thickness ratios favorable to such effects. The results indicate that λ/thickness ratios greater than 6 are propitious for extrinsic anisotropy generation and the use of equivalent media as substitutes for stratified layers are ratified for thicknesses lower than 10 meters. Also, it was observed that in most cases, intrinsic anisotropy has a main role over extrinsic anisotropy.