A comparison of common-midpoint, single-shot, and plane-wave depth migration

Abstract

A comparison of common-midpoint (CMP), single-shot, and plane-wave migration was made for simple two-dimensional structures such as a syncline and a horizontal reflector with a laterally variable reflection coefficient by using synthetic seismograms. The seismograms were calculated employing the finite-difference technique. CMP sections were simulated by 18-fold stacking and plane-wave sections by slant stacking. By applying a finite-difference scheme, the synthetic wave field was continued downward. The usual imaging condition of CMP migration was extended in order to carry out migration of single-shot and plane-wave sections. The reflection coefficient was reconstructed by comparing the migrated wave field with the incident wave field at the reflector. The results are: (1) all three migration techniques succeeded in reconstructing the reflector position; (2) as a consequence of the finite aperture of the geophone spread, only segments of the reflector could be reconstructed by single-shot and planewave migration; (3) for single-shot and plane-wave migration the reflection coefficient could be obtained; and (4) CMP migration may lead to incorrect conclusions regarding the reflection coefficient.