Beam Technology and Beam Tomography – The Curmudgeon’s Column

In my classification, beam migrations are a subset of smart migrations, a class of algorithms that uses information in the prestack input data to guide the migration operator, in contrast with brute force migrations (or dumb migrations) such as Kirchhoff and RTM that make the assumption that every point in the subsurface is a diffractor, do not use the stack information available, and make no a priori assumptions about the migrated image structure. Some hybrid algorithms that use the dips from the stack to constrain the aperture do not fit neatly in my classification, but the helicopter view still stands. One early and successful commercial implementation of a smart migration class algorithm is FBM developed by Sherwood at Applied Geophysical Services. The speed of FBM is achieved in two steps:
1) A factor of 5 to 10 in speedup is achieved using beam forming, or beam decomposition of the input data, where the number of input data is reduced by a factor of 5 to 10.
2) A factor of 10 to 100 in speedup is obtained by spreading each input trace or beam over a beam instead of a full aperture volume.

Read the full article on Mihai’s blog here >
Read the full article on the SEG Library here >

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