VSP wavefield separation using structure tensor dip masking filter

In a Vertical Seismic Profiling (VSP) acquisition, downgoing wavefields and upgoing wavefields, interfere. Both wavefields are practical in various seismic applications, However, it is needed to separate these two reflection and transmission fields. Different techniques have been proposed for VSP wavefield separation. Median filtering as well as 2D Fourier transforms are commonly used for separating the seismic wavefields. The former suffers from the averaging effect, generating artifacts, and amplitude modification due to spectral energy leakage after the inverse transform. 2D Fourier has the problem of leakage and edge effects. We propose a new approach based on the structure tensor and local dip estimation following a masking filter for VSP wavefield separation. The dip masking filter is calculated using the local dip of each point of data that can separate upgoing and downgoing wavefields from the original data. The advantage of this approach is both in preserving seismic amplitudes and in provision of a section free of fake events; this literally implies no energy leakage. The synthetic and real data examples are demonstrated to show the performance of the proposed method.