New azimuthal binning for improved delineation of faults and fractures

Abstract

We suggest and test a new way to define azimuth binning in Kirchhoff prestack migration. With this new definition, we sort seismic data by the azimuth of the average travel path traversed from the source to the subsurface image point and back to the receiver, rather than the azimuth between source and receiver on the surface of the earth. This approach avoids mixing the typically weaker side-scattered energy with the stronger in-plane reflections, thereby providing greater leverage in identifying image contributions from out-of-the-plane steeply dipping reflectors, fractures and faults. We examine the impact of this new imaging approach combined with analysis of seismic attributes that have proved useful for fracture detection, on data from the Fort Worth Basin, Texas, United States. We find that the image of features such as reflectors and discontinuities focus into azimuths perpendicular to the strike of each feature. The discrimination achieved in the azimuthal domain allows for an increased resolution in analysis of geologic features according to their strike direction. It should also result in improved residual azimuthal velocity analysis.