Generating surface-offset common-image gathers with backward wavefield synthesis

Surface-offset common-image gathers (CIGs) are an important data format for seismic velocity analysis. However, the reverse time migration (RTM) method, which is wavefield propagation based, does not directly produce surfaceoffset CIGs because it propagates waves from all the offsets together. Here, we implement the generation of surface-offset CIGs by synthesizing the backward wavefields using the forward wavefields at locations where source and receiver locations overlap. This method produces surface-offset CIGs with high accuracy and low cost when compared with those generated by backpropagating each trace separately. We adopt nonnegative least-squares filters for sparse linear deconvolution. The computational effectiveness of the proposed method increases for higher dimensions, higherorder stencils, and more complicated wave equations. The proposed method works stably on a realistic towed-streamer acquisition system with moderate geometric positioning errors between the locations of airguns and hydrophones.

Automated summary

Surface-offset common-image gathers (CIGs) are important for seismic velocity analysis. This study proposes a method to generate CIGs by synthesizing backward wavefields based on forward wavefields, which is more accurate and cost-effective compared to backpropagation of individual traces. The proposed method utilizes nonnegative least-squares filters for sparse linear deconvolution, improving computational efficiency for higher dimensions and more complex wave equations.