Understanding Amplitude Variations in 3D Acquisition and Processing for Sub-salt Imaging

Summary 3D Pre-stack depth migration (PSDM) is commonly used for improving image quality adjacent to and under complex salt bodies in the Gulf of Mexico. A study has been conducted within a mini-basin of the Garden Banks area of the Gulf of Mexico to examine the benefits of combining multi-directional datasets together through depth processing to yield the optimum near-salt and sub-salt image. Two different shooting directions produced different PSDM images in the basins and under the salt. Illumination modeling was used to understand the differences in the PSDM images. The illumination maps showed higher illumination in the basin on the survey parallel to the salt front. Under the salt the illumination was highly variable but some areas had higher illumination on the survey which was perpendicular to the salt front.