Research on diffraction wave reverse time migration imaging methods

Diffraction points in the seismic profile reflect the location information of discontinuities such as underground faults, pinching-outs, and karst caves. Therefore, the diffracted wave is of great significance for the realization of precise imaging of small-scale structures. The diffracted wave imaging schemes based on reverse time migration include the multiplication imaging condition-based method and the picking-up method in the dip-angle domain. The multiplication imaging condition-based method locates diffraction points by multiplying positive- and negative-dip angle structural profiles. And the basis of the picking-up method are characteristics of the diffracted wave in the dip angle domain. Among them, we achieve the wavefield directional decomposition with the help of the Hilbert transform and the extrapolation of the accompanying wavefield, thus realizing the imaging of structures in an inclined direction and improving the quality of the dip gathers. We also derive the imaging conditions for positive- or negative-dip angle structures which don't need directional decomposition. As a full-wave imaging approach, reverse time migration provides an imaging profile including diffraction points, which inspires us to extract the diffraction points' locations from the seismic profile through image processing. Compared with the previous two methods, this method has the characteristics of low cost, robust scalability, and localized profile processing.