Stationary-Phase Pre-Stack Time Migration in Dip-Angle Domain

Kirchhoff-type migration approach often suffers from migration noise, aliasing artifacts due to operator error, or weak noise from a truncated aperture or pre-stacked data. These noises can be attenuated by using stationary-phase migration, which only stacks the reflection energy within the Fresnel zone rather than along the whole migration aperture, and therefore obtains a higher signal-to-noise ratio (SNR) for the migration results. This paper proposes a new implementation for pre-stack time migration (PSTM) approach, which is based on stationary-phase stacking in the dip-angle domain. This implementation generates a pair of migrated dip-angle gathers in the image domain using PSTM, we can obtain the dip-angle field corresponding to the contribution of the Fresnel zones from the migrated dip-angle gathers, which allows us to remove noise outside the Fresnel zones and significantly improve the signal-to-noise ratio of the image gathers. The proposed stationary-phase PSTM could effectively handle the problem of low SNR in the migrated images, especially in the presence of steeply dipping structures. We test the method by applying stationary-phase PSTM to an overthrust model example and a 3D field data set, and both examples demonstrate that the resulting images are of good quality with the method.