CONCLUSIONS

I have presented an efficient algorithm for residual depth migration in general variable-slowness models. The algorithm consists of two steps: (1) calculating the operators with a finite-difference method, (2) applying the calculated operators to the migrated image. This algorithm is generally applicable to both post-stack and pre-stack migration, and to both common shot and constant offset geometry. I have used a synthetic example of residual depth migration of a post-stack image to demonstrate the accuracy of the algorithm. Further experiments are necessary to determine how efficient the residual migration is in comparison to full migration.

 

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Figure 1 Synthetic slowness model. High intensities denote high velocities or low slowness. The solid curves indicate the boundaries of layers.

 

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Figure 2 Synthetic zero-offset section generated from the slowness model in Figure 1.

 

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Figure 3 Image migrated with a constant slowness. The dashed curves shows the true positions of the reflectors

 

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Figure 4 Image after residual depth migration. The dashed curves shows the true positions of the reflectors.