Multiple Suppression by Hyperbolic Vector Median Filtering of Deep-Water Ocean-Bottom PS Waves

The removal of multiples is crucial for the imaging of ocean-bottom seismic data. However, PS-wave-related multiple recognition and attenuation methods have rarely been studied. We propose a morphological difference-based multiple suppression method called hyperbolic vector median filtering for PS waves received from the deep ocean bottom. This method was implemented in the PS-wave common-image domain. First, we produced a PS-wave common-image gather (CIG) by using prestack time migration (PSTM), during which sources were extrapolated from sea surface to seafloor, and PS-wave moveouts were simultaneously corrected to be hyperbolic. Subsequently, we generated the root-mean-square (rms) velocity spectrum corresponding to the CIGs and picked up velocities of PS-wave primaries. The picked PS-wave velocity is an effective velocity, as it is related to both P- and S-wave rms velocities and is employed to build hyperbolic time windows. Finally, we designed a hyperbolic vector median filter to suppress multiples from PS-wave CIGs. The numerical examples demonstrate that hyperbolic vector median filtering can suppress different types of multiples and accurately separated PS-wave primaries. The application to field OBN data demonstrates the effective attenuation of first- and second-order multiples developed from shallow and deep formations. Two test results demonstrate that the proposed method effectively suppresses the imaging artifacts related to multiples on the PS-wave migration section.