Seismic imaging is a general term that geophysicists now use to describe processes that convert seismic data into a geological "representation" of the subsurface. These "representations" may vary from simple structural images that use migration algorithms, to ones that estimate rock properties with algorithms that are based on inversion theory. This paper will address the basic concepts of modelling and poststack migration to build a foundation of knowledge for the companion paper (included in this Report) on prestack migration and seismic inversion.
The migration algorithms will be described by the three classifications of Kirchhoff, FK, and downward-continuation. To assist in describing these algorithms, a number of models will be presented that start with a known geological cross-section, which are then used to create seismic data. These models are then used to describe features of the migration algorithms.
Most of the material in this paper has been taken from my course notes that are published by the SEG. These contain an extensive list of references that have not been included in this review with the intent to keep it more readable. In addition, little mathematics is used, which are replaced by basic physical principles that are used with the intention of providing a heuristic foundation of the migration principles.
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