Migration of the survey

I now proceed to the final imaging steps of migrating every shot record and summing them. Figures a and b show the final migration result for both primaries and multiples. The two final images are quite similar although the migration of the primaries with the impulsive source is crispier and less noisy than with multiples. Nevertheless the migration of multiples yields an accurate image of the earth. After closer inspection, it seems that the flanks of the canyon in the middle above the salt dome is better defined with the multiples.

The illumination maps displayed in Figures c and d are almost identical after summation of all shot contributions. This comes from the acquisition geometry at the two ends of the survey. This first result is rather encouraging and shows that multiples can be used to image the earth.

 

compmig
Figure 7 Final migration results and illumination maps. (a) Migration of the primaries. (b) Migration of the multiples. (c) An illumination map for all the impulsive sources. (d) An illumination map for all the areal sources.