Improving Subsalt Imaging by Image Conditioning and Enhancement with RTM Vector Image Partitions - A GoM Case Study

Abstract

SUMMARYSubsalt imaging remains challenging despite a growing need for more accurate subsalt characterization. Long offsets, wide-azimuth (WAZ), and full-azimuth (FAZ) acquisition technologies have provided stepchange improvements in illumination, multiple attenuation and signal-to-noise ratio. Recently developed more advanced anisotropic velocity model building techniques, have also greatly enhanced our ability to build accurate salt models and reduce velocity error. Reverse-time Migration (RTM) has become the preferred imaging algorithm due to its superior tolerance for complex salt geometry compared with traditional ray-based Kirchhoff migration. However, even with these developments, subsalt imaging still remains a significant challenge. Recently, Vector Image Partitions (VIPs) from RTM have proven valuable for enhancing the image of challenging subsalt structures. In this paper, we present a new method for optimizing the final migrated image through enhancement of the consistent signal and suppression of noise among VIPs. We demonstrate the effectiveness of this method with a case study from the Gulf of Mexico. The result shows great improvements in the subsalt image quality in terms of signal to noise ratio, reflector continuity, and wavelet consistency along reflectors.