Deprimary reverse time migration angle gathers with a stabilized Poynting vector

Abstract

Deprimary reverse time migration (RTM) mitigates the problem of low-wavenumber noise and false events in conventional RTM, and the generation of high-quality angle-domain common-image gathers or angle gathers during deprimary RTM greatly extends its further applications in velocity model updating and subsurface parameter inversion. Poynting-vector-based methods are the most efficient approach to extract angle gathers from RTM or deprimary RTM. However, the instability problem of Poynting-vector-based methods seriously degrades the quality of the generated angle gathers. The instability problem arises from the oscillatory nature of the Poynting vector. To overcome this issue, we propose a novel approach by harnessing the extra simulated Hilbert transformed wavefield in deprimary RTM. Our approach consists of adding the conventional Poynting vector with an ancillary one derived from the Hilbert transformed wavefield, which allows us to eliminate the oscillatory nature of the conventional Poynting vector and obtain a stable algorithm to extract high-quality angle gathers from RTM or deprimary RTM. By using numerical examples with two synthetic data sets and a field data set from the deepwater Gulf of Mexico, we prove the effectiveness of our method in generating high-quality angle gathers.