We present a method of layer replacement based on the Kirchhoff integral solution to the scalar wave equation. The term 'layer replacement' refers to replacing the overburden velocity with the velocity of the substratum, thereby eliminating raypath bendings at the interface between the overburden and the substratum. It is the raypath bendings that induce distortions and disruptions on reflections beneath a complex structure. When implemented before stack, layer replacement provides an opportunity to revise velocity estimates after correcting for the nonhyperbolic moveout on CMP data caused by a complex overburden. As a result, layer replacement also yields an improved unmigrated stack section. Imaging can then be completed by time migration after stack. We demonstrate the layer-replacement technique on field data with irregular water-bottom topography.

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