Reconstructing the primaries of PP and PS waves by elastic Marchenko method

Multiples always introduce artifacts in reverse time migration (RTM). Especially for elastic RTM, the PP and PS images may contaminated by transmitted P-S (or S-P) wave. In this study, we propose an approach to reconstruct the primaries of PP and PS waves. The primaries means the wave (P-P or P-S) reflected only once at the interface in the subsurface. The approach mainly contains three steps, including wavemode decomposition, Marchenko redatuming, and convolutional interferometry. First, the P and S waves in the surface measurements are decomposed using decoupled propagation method. Second, two components of upgoing Green's functions of PP and PS waves are retrieved using iterative Marchenko approach. At last, the first events picked from the upgoing Green's functions are convolved with estimated direct P wave to reconstruct the primaries. The reconstructed primaries used in elastic RTM can avoid the artifacts generated by internal multiples and transmitted P-S (or S-P) wave. A numerical test proves the validity of this approach. The approach is supposed to be applied in more complex media.
© 2019 SEG