Efficient Elastic Reverse Time Migration Using Decoupled Propagator for Multicomponent Seismic Data

Summary Elastic reverse-time migration (RTM) has shown significant advantages in obtaining depth-domain multi-wave imaging results, but also remains a considerable challenge in its practical application partly owing to the complexities of multi-mode elastic wavefields in the heterogeneous medium. We present a decoupled P- and S-waves propagator to form an efficient elastic RTM framework, without the assumption of homogeneous Lame´ parameters. Also, there is no mode conversion occurs using the proposed propagator even in the case of shear modulus discontinuities, avoiding the imaging artifacts caused by the unphysical wave-mode conversion. In the proposed elastic RTM framework, the source-side forward wavefield is simulated using a P-wave propagator. The receiver-side wavefield is back extrapolated using the proposed propagator, with the recorded multicomponent seismic data as input. Compared to the elastic RTM framework, the proposed framework reduces the computational complexities effectively but nearly preserves the imaging accuracy. We demonstrate its accuracy and efficiency using two synthetic examples, from which the proposed method shows comparative results but superior efficiency.