Robin Fletcher

Suppressing Artifacts In Prestack Reverse Time Migration

Two-way migration methods require significantly greater computational resources than one-way migration methods. However, their advantage is that they can not only handle multiarrivals, but have virtually no dip limitation, enabling imaging of overturned reflections. Reverse time migration, a wave equation technique using two-way propagation, correctly handles both multiarrivals and the phase changes due to caustics, but by using two-way propagation, does not suffer from dip limitation like one-way downward continuation techniques. Although one-way wave equation techniques can be implemented and classified as true-amplitude migrations, reverse time migration makes no approximations that must be corrected to control amplitude.

Amplitude Preservation for PSDM Processing

As seismic exploration moves to more complex and challenging geologic environments, Anisotropic Prestack Depth Migration is becoming the standard imaging technology. At the same time, there is high interest to use seismic amplitudes in these complex environments for risk assessment and reservoir characterization, objectives that require accurate amplitude preserving prestack depth migration. In this paper we review recent advances made to ensure depth migration algorithms maintain the quality of relative amplitudes. We verify with simple synthetics the amplitude response of Reverse Time Migration, Adaptive Beam Migration and Kirchhoff Migration algorithms, and demonstrate how these can be used successfully, under controlled circumstances, for AVO/AVA and Absolute Acoustic Inversion in media with lateral velocity variations.