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Double plane-wave reverse-time migrationNormal access

Authors: Z. Zhao, M.K. Sen and P.L. Stoffa
Journal name: Geophysical Prospecting
Issue: Vol 65, No 6, November 2017 pp. 1541 - 1558
DOI: 10.1111/1365-2478.12507
Organisations: Wiley
Language: English
Info: Article, PDF ( 10.33Mb )

Summary:
We develop a new time-domain reverse-time migration method called double planewave reverse-time migration that uses plane-wave transformed gathers. Original shot gathers with appropriate data acquisition geometry are double slant stacked into the double plane-wave domain with minimal slant stacking artefacts. The range of planewave components needed for migration can be determined by estimating the maximum time dips present in shot gathers. This reduces the total number of input traces for migration and increases migration efficiency. Unlike the pre-stack shot-profile reverse-time migration where the number of forward propagations is proportional to the number of shots, the number of forward propagations needed for the proposed method remains constant and is relatively small even for large seismic datasets. Therefore, the proposed method can improve the efficiency of the migration and be suitable for migrating large datasets. Double plane-wave reverse-time migration can be performed for selected plane-wave components to obtain subsurface interfaces with different dips, which makes the migration method target oriented. This feature also makes the method a useful tool for migration velocity analysis. For example, we are able to promptly obtain trial images with nearly horizontal interfaces and adjust velocity models according to common image gathers. Seismic signal coming from steeply dipping interfaces can be included into the migration to build images with more detailed structures and higher spatial resolution as better velocity models become available. Illumination compensation imaging conditions for the proposed method are also introduced to obtain images with balanced amplitudes.

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