HR: 08:45h
AN: S51A-03    [PDF]
TI: Prestack cascaded Stolt migration
AU: Agnihotri, Y
EM: agnihotri@student.utdallas.edu
AF: University of Texas at Dallas, FO 3.104C, Founders Annex 2601, N.Floyd Road, Dallas, TX 75083 United States
AU: * Sen, S
EM: ssen@geosc.psu.edu
AF: Pennsylvania State University, 427 Deike building University Park, State College, PA 16802 United States
AB: Residual migration has proved to be an important tool in seismic imaging and in velocity analysis in complex media. Recently Sava (2003) showed how residual migration can be formulated in the prestack domain as a function of a nondimensional parameter, $\gamma$, which is the ratio of the reference velocity used in migration and the correct medium velocity. We extend Sava's work and show how cascaded migration can also be formulated in the prestack domain as a function of $\gamma$. We show how we can apply a series of transformations to the initial incorrectly migrated image improving the focusing of the image after each transformation stage without making any assumptions about the medium velocity. In fact the sequence of transformations will ultimately yield the correct image as long as the product of the $\gamma$ values used at each stage equals the ratio of the initial migration velocity and the correct medium velocity. We also show how cascaded migration can be used to overcome the restriction of small slowness perturbation imposed by the Born approximation. We use large $\gamma$ values during each of the transformation stage (each cascade) so that the perturbation in the image does not become large and violate the Born approximation. The slowness perturbation is then inverted from the corresponding perturbation in the image for each of the individual cascades and the total slowness anomaly is obtained by summing up each of the small slowness perturbations. The process of inverting for each of the small slowness anomalies can also be done in parallel to increase the efficiency.
DE: 0900 EXPLORATION GEOPHYSICS
DE: 0902 Computational methods, seismic
DE: 0910 Data processing
DE: 0935 Seismic methods (3025)
SC: Seismology [S]
MN: 2003 Fall Meeting