Anisotropy from seismic data – a synthetic model and other considerations

Summary

Wide azimuth, long offset 3D seismic datasets are widely available on-shore USA. This data lends itself to more detailed studies of the reservoir intervals and trying to predict anisotropy at the unconventional shale interval is one such application. Especially azimuthal variations in normal moveout velocity are used to infer natural fracture networks.

In the presence of a well-defined fracture network, the wave will propagate faster along the main fracture direction and slower perpendicular to it. Obviously, this information should provide us with the dominant direction of the fracture swarm and the difference between those 2 velocities is indicative for the fracture density. This behavior can be seen on COVA (common offset varying azimuth) gathers as a sinusoid in the higher offset range. But can we truly extract these properties from seismic? This work investigated the concept on a wide azimuth, elastic, anisotropic synthetic dataset that mimics the geology in the Anadarko Basin.

• seismic anisotropy