Source wavefield reconstruction using the Remez exchange algorithm for reverse time migration

Abstract

Summary Reverse time migration (RTM) requires source and receiver wavefields available at the same time step. However, the source and receiver wavefields are propagated in the forward and reverse time order, respectively. To reduce storage overhead, we develop a memory-efficient source wavefield reconstruction method, which reconstructs the source wavefields in the inner area using a linear combination of the boundary wavefields. We optimize the reconstruction coefficients based on the minimax approximation with the Remez exchange algorithm. Dispersion analyses and numerical results reveal that the proposed method exhibits greater accuracy than the existing method, which estimates the reconstruction coefficients based on least-squares (LS). 3D RTM example shows that the proposed method can obtain acceptable images, which are close to those of the conventional method storing M layers of boundary wavefields. The memory usage of the proposed method is just 1/M of the conventional M-layer method.