P-wave Azimuthal Anisotropy Analysis

Infer reservoir fracture properties directly from P-wave seismic data

Azimuthal anisotropy may have significant effects on a wide-azimuth seismic survey - either for towed streamer or ocean-bottom cable (OBC) configurations. If the geometry is suitable, these effects can be detected on conventional P-wave seismic data by analyzing the azimuthal variation of reflection amplitude, interval velocities, or AVO attributes. The amplitude and velocity effects may be observed directly from careful processing and analysis of appropriate azimuth sectors.

For azimuthal AVO, the gradient and intercept are analyzed in such sectors to determine the offset variation of the reflectivity with azimuth. This step is carried out independently on each sector and the attributes compiled to identify any azimuthal variations.

A more rigorous approach is to create substacks of the offset and azimuths, which are used as inputs to determine a series of multiindependent solutions of the azimuthal variations - after Mallick (1994) and Ruger (1997).

WesternGeco provides both standard and higher-order solutions for anisotropic AVO gradient terms.

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