Robust incident-angle field estimation: a one-way wave propagator approach

Abstract

The incident angle is a very important piece of information in many processing steps for seismic data, but it cannot be easily and directly estimated in many typical and familiar migration processes, such as shot-profile wave equation migration and reverse time migration. In this paper, we first revisit and analyse some popular schemes of estimating the incident-angle field. Then we present a robust method to estimate the incident-angle field in a 2D/3D heterogeneous isotropic media based on a one-way wave propagator. Unlike the band-limited wavefield, the incident-angle field is estimated by the division of two impulse responses of the monochromatic wavefield in order to reduce computation. The impulse responses are the derivative of the angle-weighted image extracted by multiplying an extra imaging weight in the conventional migration process and conventional image. The tilted coordinate system is adopted in our method to avoid the steep-angle limitation of one-way wave propagators. By comparison with other methods, our method can estimate the incident-angle field more accurately with higher efficiency and less memory cost. Computed incident-angle fields of a 2D layered model and 3D field data example demonstrate the generality and flexibility of the method.