Common-reflection-point stacking in laterally inhomogeneous media

An important seismic reflection-imaging process which is widely applied in practice in an approximate form is the simulation of a zero-offset (ZO) section from a set of common-offset (CO) sections. Rather than using the familiar common-midpoint (CMP) stack (which suffers from reflection-point dispersal when the reflectors are dipping), the aim now increasingly is to perform an accurate common-reflection-point (CRP) stack. In the latter case, all primary CO reflections used for the simulation of a particular ZO reflection are expected to have a common reflection point. A CRP stack can be performed with a macro-velocity model or with the near-surface velocity only. The fundamental CRP reflection and stacking trajectories involved in both of these CRP stacking techniques are inherently related. The aims of this paper are (a) to give some simple analytic formulae for these trajectories for the constant-velocity case and (b) to describe two CRP stacking methods for 2D laterally inhomogeneous media that make use of the formulae.