3D/4C Emilio: Azimuth processing and anisotropy analysis in a fractured carbonate reservoir

Abstract

In recent years multicomponent 3D seismic data have demonstrated their usefulness for characterizing fractured reservoirs. Many theoretical and field studies have shown that variation of attributes (such as velocity, amplitude, and frequency of P-wave data acquired along different source to receiver paths), can be used as an indicator of azimuthal anisotropy. Lateral heterogeneity encountered by the different azimuth source-receiver raypaths could give rise to azimuthal variations in traveltime and/or transmission characteristics, and thus masquerade as azimuthal anisotropy. To remove this ambiguity, mode-converted split shear waves can be employed. S-wave splitting across a fractured medium is a well studied and understood phenomenon that exploits the traveltime delay between the fast and the slow S-waves, and their polarization azimuths to infer fracture properties.