A robust method of extracting angle-domain common-image gathers from shot-profile wave equation migration

Zhang, J., 2012. A robust method of extracting angle-domain common-image gathers from shot-profile wave equation migration. Journal of Seismic Exploration, 21: 267-280. Shot-profile pre-stack depth migration is quite attractive for sparse-shot wide-azimuth geometries. Meanwhile, angle-domain common-image gathers (ADCIGs) have become an essential tool in seismic processing. After revisiting the popular schemes of extracting ADCIGs, we present a robust method to estimate the incident-angle field and extract ADCIGs from shot-profile wave equation migration. The cosines of the incident-angle can be estimated from the ratios between the square roots of the angle-weighted image gathers’ Laplacian operators and the amplitude values from the conventional common-image gathers. The angle-weighted image gathers can be extracted by multiplying an extra imaging weight including local propagation velocity and angular frequency in conventional shot-profile wave-equation migration process, while the conventional common-image gathers are obtained using the cross-correlation imaging condition. A stable division at selected wave crests with large amplitude ensures the stability and avoids noise interference. Finally, we separate the shot-domain common-image gathers (SDCIGs) into different angle bins using incident-angle field to extract ADCIGs. Numerical examples demonstrate that the method is stable and memory-efficient and independent of structural dips.
- Bleistein, N., Cohen J.K. and Stockwell, J.W., 2001. Mathematics of multidimensional seismic
- inversion. Springer Verlag, New York.
- Biondi, B., 2006, 3D Seismic Imaging. SEG, Tulsa, OK.
- Claerbout, J.F., 1985. Imaging the Earth’s Interior. Blackwell Scientific Publications, Inc., New
- York.
- De Bruin, G.G.M., Wapenaar, C.P.A, and Berkout, A.J, 1990. Angle dependent reflectivity by
- means of prestack migration. Geophysics, 55: 1223-1234.
- Lecomte, I., 2008. Resolution and illumination analyses in PSDM: A ray-base approach. The
- Leading Edge, 27: 650-663.
- Levin, F.K, 1971. Apparent velocity from dipping interface reflection. Geophysics, 36: 510-516.
- Rickett, J. and Sava, P.C., 2002. Offset and angle-domain common imaging-point gathers for
- shot-profile migration. Geophysics, 67: 883-889.
- Sava, P.C. and Fomel, S., 2002. Offset and angle-domain common-image gathers by wavefield
- continuation methods. Geophysics, 68: 1065-1074.
- Sava, P.C. and Fomel. S., 2005a. Coordinate-independence angle-gathers for wave equation
- migration. Expanded Abstr., 75th Ann. Internat. SEG Mtg., Denver: 2052-2057.
- Sava, P.C. and Fomel, S., 2005b. Wave equation common-angle gathers for converted waves.
- Expanded Abstr., 75th Ann. Internat. SEG Mtg., Denver: 947-950.
- Shragge, J., 2012. Angle-domain common-image gathers in generalized coordinates. Geophysics,
- 74: S47-S56.
- Slotnick, M.M., 1959. Lessons in Seismic Computing. Geyer, R.A. (Ed.). SEG, Tulsa, OK.
- Xie, X.B. and Wu, R.S., 2002. Extracting angle domain information from migrated wavefield.
- Expanded Abstr., 72nd Ann. Internat. SEG Mtg., Salt Lake City: 1360-1363.
- Yoon, K., Guo, M., Cai, J. and Wang, B., 2011. 3D RTM angle gathers from source wave
- propagation direction and dip of reflector. Expanded Abstr., 81st Ann. Internat. SEG Mtg.,
- San Antonio: 3136-3140.
- Zhang, Q. and McMechan, G.A., 2011. Angle domain common image gathers extracted from
- reverse time migrated images in isotropic acoustic and elastic media. Expanded Abstr., 81st
- Ann. Internat. SEG Mtg., San Antonio: 3130-3135.
- Zhang, Y., Xu, S., Zhang, G. and Bleistein, N., 2005. Angle domain true amplitude wave equation
- migration. Extended Abstr., 67th EAGE Conf., Madrid: F045.
- Zhang, Y., Xu, S., Bleistein, N. and Zhang, G., 2007. True-amplitude, angle-domain,
- common-image gathers from one-way wave-equation migrations. Geophysics, 72: $49-S58.