Source-Receiver Migration

After the data reduction afforded by the datuming and appropriate padding in offsets, we input to the source-receiver migration an even smaller dataset that had only 32 CMPs in the inline direction, 144 CMPs in the crossline direction, 120 offsets in the inline direction, 24 offsets in the crossline direction and 200 frequencies, just about 20 Gb of data. The data was migrated with 600 depth steps at 10 m (starting at the depth of the water-bottom at zero crossline CMP or about 1000 m).

Figure  shows the inline dimensions of one SODCIG. The data aperture was very limited and so there are some migration artifacts. Again, note that the multiples migrate to the negative subsurface offsets and are well separated from the primaries.

 

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Figure 12 Inline SODCIG obtained by source-receiver migration.

By contrast with the inline direction, the sampling of the crossline offsets and CMPs is very coarse and the results of the migration are not nearly as good as illustrated in Figure  which shows a cube of crossline CMPs as a function of crossline offset. Although the primaries, and the multiple, have been relatively focused toward zero subsurface offset, there is still a lot of energy smearing to both positive and negative crossline subsurface offsets.

 

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Figure 13 Crossline SODCIG obtained by source-receiver migration.

Figure  shows a zero subsurface-offset cube of migrated data. The image is good in the inline direction and somewhat noisy in the crossline direction. A comparison with the result of the common-azimuth migration Figure  shows the improvement in the crossline image.

 

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Figure 14 Zero subsurface-offset cube migrated with source-receiver migration.