Reverse time migration of phase-encoded all-order multiples

Abstract

Multiples follow long paths and carry more information on the subsurface than primary reflections, making them particularly useful for imaging. However, seismic migration using multiples can generate crosstalk artifacts in the resulting images because multiples of different orders interfere with each other and crosstalk artifacts greatly degrade the quality of an image. We form a supergather by applying phase-encoding functions to image multiples and stacking several encoded controlled-order multiples. The multiples are separated into different orders using multiple decomposition strategies. The method is referred to as the phase-encoded migration of all-order multiples (PEM). The new migration can be performed by applying only two finite-difference solutions to the wave equation. The solutions include backward extrapolating the blended virtual receiver data and forward propagating the summed virtual source data. Our approach can significantly attenuate crosstalk artifacts and also significantly reduce computational costs. Numerical examples demonstrate that PEM can remove relatively strong crosstalk artifacts generated by multiples and is a promising approach for imaging subsurface targets.