Anisotropy processing of multi-component seismic data – Part 1: Theory and Implementation

Abstract

Summary An oil-gas reservoir can be treated as an orthorhombic medium which can be considered as a combination of VTI and HTI media. It means, for a given azimuthal direction, that an orthorhombic medium can be treated as a VTI medium. To process the seismic reflection data acquired from such a medium (the reservoir), the common practice is to separate the processing into two stages: anisotropy processing for a VTI medium and anisotropy processing for a HTI medium. In the first stage, we can ignore the HTI features and apply VTI anisotropy processing to this data, from which we can estimate the velocity and anisotropy parameters and obtain seismic images. Actually, the results are the average results for the whole dataset. Then we use the estimated velocities and anisotropy parameters as an initial model for HTI processing. In HTI processing, we need to separate the seismic data according to the azimuthal direction of the offset. Then we can carry on VTI processing for each set of azimuthal data. The results will be dependent on the azimuthal direction. The azimuthal dependence of velocity and anisotropy parameters can be used to estimate the fracture direction and strength of anisotropy of the reservoir.