High resolution 3D seismic undershooting acquisition over platforms and seismic processing challenges in a gas producing field

Abstract

： One of the many challenges of seismic acquisition associated with existing fields is existence of surface platforms. The block where the seismic operation was conducted is located in offshore Sarawak and there are 3 discovered gas fields and a number of near-field exploration targets. The legacy 3D seismic survey covering the block was conducted in 1992 with limited acquisition specifications, such as short cable length and low volume airguns, in comparison to the technology of today. Hence new 3D seismic acquisition with broadband processing was commissioned which included the undershooting operation across 2 production facilities to improve the seismic imaging of the deeper exploration targets and to optimize well engineering. Overall, the new 3D data were acquired with a successful undershooting operation followed by survey merging and matching in the processing stage. The new 3D data show better seismic reflection continuity, a higher signal to noise （ S/ N ） ratio, clearer images, and a more accurate velocity model in the deep section, allowing for a better interpretation of the deep exploration targets.