Full Wavefield Migration: a closed-loop imaging approach including all multiple scattering.

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Published Date

2016-1

Language

English

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Abstract

Multiple scattering is usually ignored in migration algorithms, while it is a genuine part of the physical reflection response. When properly included, multiples can add to the illumination of the subsurface, while their cross-talk effects are removed. Therefore, we introduce full wavefield migration (FWM). It includes all multiples and transmission effects in deriving an image via an inversion approach. Since it tries to minimise the misfit between modelled and observed data, it may be considered as a full waveform inversion process. However, FWM involves a forward modelling process that use the estimated seismic image (i.e. the reflectivities) to generate the modelled full wavefield response, while a smooth migration velocity model can be used to describe the propagation effects. By this separation, a more linear inversion
problem is obtained. Moreover, during the forward modelling the wavefields are
computed separately in the incident and scattered directions, which allows the implementation of various imaging conditions, such as imaging reflectors from below - and avoids low-frequency image artifacts, such as typically observed during reverse-time migration. Based on various numerical data examples for the 2D and 3D case the advantages of this methodology are demonstrated.