Fault shadow distortions on 3D seismic data and their removal by depth processing.

Summary

We noticed during depth processing on real seismic data with fault shadows that:

- Appearance of fault shadows and the convergence speed of the tomographic inversion depend on the acquisition direction;

- Tomographic depth-velocity modelling usually produces models that closely follow geology; but sometimes the models contain odd looking nongeological anomalies; in both cases the depth migration delivers distortion free seismic images;

- Anisotropy in faulted areas creates additional image distortions.

To examine these effects and optimize our depthprocessing workflow, we created several synthetic seismic datasets for different types of velocity anomalies associated with faults in isotropic and anisotropic media and different acquisition directions.

Key words::

• depth imaging
• fault
• velocity modelling