A SYNTHETIC DATA EXAMPLE

I used synthetic data to test the program of prestack slant stack migration. Two hundred 24-fold CMP gathers were generated according to the model in Figure 1. There are two horizontal layers, one slant event, and four point diffractors. A velocity function V(z)=(2000+2*z) meters per second was used to generate the synthetic dataset with the prestack Kirchoff modeling program. The record length is 1.6 seconds and the sampling rate is 8 milliseconds. The CMP interval is 25 meters and the far offset is 460 meters. The near offset section is shown in Figure 2.

To migrate the synthetic dataset, I followed the processing steps described in the preceding section. Figure 3 shows one of CMP gathers after slant stack transformation, with a slant parameter p from 0 to 0.48 seconds per kilometer. After the prestack slant stack migration, I obtained the gather shown in Figure 4, at the same CMP location as in Figure 3. After migration almost all the events were lined up.

Finally, I stacked all the different p sections to get the migration section shown in Figure 5. Comparing Figures 5 and 1 shows that the migration algorithm works well for the synthetic dataset.

 

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Figure 1 A model for generating synthetic data

 

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Figure 2 A near-offset section of synthetic data

 

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Figure 3 A CMP gather after slant stack transformation

 

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Figure 4 The CMP gather in Figure 3 after prestack slant stack migration

 

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Figure 5 Migrated synthetic data