CRAM and Kirchhoff images of a west Africa salt structure

Abstract

The main objective of this project was to optimize the seismic image underneath the salt overhangs for better interpretation of the reservoir beds as they approach the salt body. Target depths from 680 to 5970 m were imaged, with input and output bins of 12.5 × 12.5 m and a depth step of 5 m. The velocity model was set up using Kirchhoff migration with some minor modification after WEM imaging. Total area imaged was 23 km2. Input was from a square about 160 km2. CRAM (common reflection-angle migration) imaging resulted in better imaging of the steep salt flanks, steeply dipping beds, and improved lateral spatial resolution. In addition, the CRAM image indicates that the salt model would benefit from further adjustment, although this would probably not materially affect the shallower section.