Wide-azimuth angle gathers for wave-equation migration |

**Paul Sava (Center for Wave Phenomena, Colorado School of Mines)**
*Ioan Vlad (currently Fusion Petroleum Technologies, formerly Statoil)
*

Extended common-image-point-gathers (CIP) contain all the necessary
information for decomposition of reflectivity as a function of the
reflection and azimuth angles at selected locations in the
subsurface. This decomposition operates after the imaging condition
applied to wavefields reconstructed by any type of wide-azimuth
migration method, e.g. using downward continuation or time reversal.
The reflection and azimuth angles are derived from the extended
images using analytic relations between the space-lag and time-lag
extensions. The transformation amounts to a linear Radon transform
applied to the CIPs obtained after the application of the extended
imaging condition. If information about the reflector dip is
available at the CIP locations, then only two components of the
space-lag vectors are required, thus reducing computational cost and
increasing the affordability of the method.
Applications of this method include the study of subsurface
illumination in areas of complex geology where ray-based methods are
not usable, and the study of amplitude variation with reflection and
azimuth angles if the subsurface subsurface illumination is
sufficiently dense. Migration velocity analysis could also be
implemented in the angle domain, although an equivalent
implementation in the extended domain is cheaper and more effective.

- Introduction
- Imaging conditions
- Moveout function
- Angle decomposition
- Examples
- Discussion
- Conclusions
- Acknowledgments
- Bibliography
- Appendix A
- About this document ...

Wide-azimuth angle gathers for wave-equation migration |

2013-08-29