Reverse Time Migration Method for Joint Imaging of Multiples and Primaries in Vertical Seismic Profiling

Vertical seismic profiling (VSP) has garnered widespread attention because of its ability to provide high-quality seismic data. Owing to the unique characteristics of VSP observation systems, conventional multiple-wave imaging methods designed for surface seismic data are often not suitable for VSP data. Additionally, the existing research lacks methods capable of simultaneously imaging surface and interbed multiples in asymmetric observation systems. Here, the reverse time migration (RTM) imaging problem of multiple VSP waves is addressed, and a joint RTM imaging method is proposed for primary and multiple waves. Without the need to predict or separate multiple waves, this method utilizes seismic signals containing primary and multiple waves to replace wavelet excitation at the source location. Primary waves, surface multiples, and interbed multiples are simultaneously imaged, addressing the limitations of traditional VSP imaging methods that can only image areas near observation wells. Numerical tests demonstrate that the proposed method provides a broader effective imaging range and higher image quality than traditional VSP RTM methods.