Azimuthai simultaneous elastic inversion for fracture detection

Abstract

Azimuthai AVO has proved to be useful to predict fractures. However, there are a number of limitations with the technique including the fact that only band limited fractional elastic parameters are estimated. Further, the method is derived for the case of an isotropic over HTI anisotropic half‐space. It is not theoretically valid for the case of two anisotropic half‐spaces. In order to overcome these limitations this paper develops and demonstrates a new (patent pending) azimuthal simultaneous elastic inversion. Azimuth‐ and angle‐limited seismic traces are modeled using the anisotropic Zoeppritz equation to generate equivalent reflectivity volumes which are then convolved with appropriate user defined wavelets, generating 3D volumes of the fracture parameters. HTI anisotropy, the lowest symmetry which describes fractures, is used in this implementation. Alternative parameterizations using rock physics models are examined to reduce and constrain the parameterization. The algorithm is demonstrated on both synthetic and real seismic data with good results.