On the inverse propagation of surface receiver wavefields in 1.5-dimensional joint migration inversion

Joint migration inversion (JMI) technology has great potential in exploiting multiples in seismic data for both velocity model building and seismic migration, but it faces the previously published amplitude-versus-offset (AVO) challenge: the angle-independent wavefield modeling used in the current JMI cannot simulate the correct AVO effect in data, but this modeling engine is still required in order to avoid over-parameterizing a solution space. By using a velocity model and a density model to parameterize the solution space, the AVO challenge can be adequately addressed by one-way operators for 1.5-dimensional (1.5D) media. In this paper, we propose a new concept, which is named 'inverse propagation' of receiver wavefields, for JMI in 1.5D media, and we derive the complete theory behind this new concept. We will demonstrate that our inverse propagation is a physically inverse process to reconstruct wavefields in the subsurface with the effects from transmission, reflection and multiples correctly accounted for, while the old backward propagation scheme for receiver wavefields in the previous JMI technology is a not satisfying approximation. This work paves a solid way to further develop the 1.5D JMI theory.