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Zero-offset migration

Jon Claerbout

In chapter [*] we discussed methods of imaging horizontal reflectors and of estimating velocity $v(z)$ from the offset dependence of seismic recordings. In this chapter, we turn our attention to imaging methods for dipping reflectors. These imaging methods are usually referred to as ``migration'' techniques.

Offset is a geometrical nuisance when reflectors have dip. For this reason, we develop migration methods here and in the next chapter for forming images from hypothetical zero-offset seismic experiments. Although there is usually ample data recorded near zero-offset, we never record purely zero-offset seismic data. However, when we consider offset and dip together in chapter [*] we will encounter a widely-used technique (dip-moveout) that often converts finite-offset data into a useful estimate of the equivalent zero-offset data. For this reason, zero-offset migration methods are widely used today in industrial practice. Furthermore the concepts of zero-offset migration are the simplest starting point for approaching the complications of finite-offset migration.