Elastic Wave Vector Decomposition for Common-Shot Multicomponent Data Using Pure Wave Equation in Transversely Isotropic Media

Abstract

Anisotropic elastic wave vector decomposition for common-shot multicomponent data is a critical step in multicomponent seismic exploration. It is more difficult than the separation for elastic wavefield snapshots because the spatial derivatives along vertical direction cannot be calculated directly. In this letter, we propose an effective workflow to implement elastic wave vector decomposition for common-shot multicomponent data based on the pure-wave equation in transversely isotropic (TI) media. First, we extrapolate the multicomponent data backward in time to a reference surface using an anisotropic elastic wave equation, implement wave-mode separation by the projection of the extrapolated anisotropic elastic wavefields onto the polarization vectors of P- and S-wave-modes, and record the separated pure-wave data at the reference depth. Second, we extrapolate the separated anisotropic pure-wave data forward in time using the anisotropic pure-wave equations, perform the vector decomposition by the projection of the extrapolated pure-wave wavefields onto the polarization vectors of P- and S-modes, and record the vector anisotropic pure-wave data at the recording surface. This method can produce vector pure-mode data from the anisotropic medium with relatively high accuracy. Synthetic examples show the feasibility of this method.