How seismic anisotropy improves the reliability of exploration DHI (AVO)
Over the past two decades seismic anisotropy has increased its role in many seismic processing and inversion workflows. The inadequacy of an isotropic velocity model has been emphasized in prestack depth migration (PSDM), which is highly sensitive to the accuracy of the velocity field. Moreover the correct characterization of the anisotropic elastic properties of subsurface formations is fundamental for the identification of explorative targets. In this paper, we discuss an example of integrated workflow based on anisotropic Thomsen’s parameters estimation, velocity and AVO models. We present interesting results of modelling for special cases of exploration interest, highlighting the anisotropic effects for gas sands embedded in shales. Our approach has been applied to a real dataset, confirming the importance of models that account for the seismic anisotropy. We demonstrate that anisotropy is the physical factor that could explain the inability of elastic synthetics to match the prestack amplitudes of field data in some cases. These considerations led to more realistic reservoir models and explained some pitfalls in AVO interpretation.