Multi-Azimuth Imaging for Deep-Water Pre-Salt Reservoirs in Santos Basin, Brasil

This paper presents a collaborative PETROBRAS-CGGVeritas project for optimizing the seismic image of Santos Basin pre-salt structures. For this study, 200 km2 of the Lula field (ex Tupi) was chosen as the pilot area. The target reservoir lies below 2000 m of water, then 1000 m of sediments and 2000 m of salt. Because the Top Of Salt presents a highly variable topology, we investigate how it’s geometry influences the illumination at the Base Of Salt level and the consequences on the pre-salt reservoir seismic image. The modeling of three narrow azimuth acquisitions showed highly spatially variable illumination at the base of salt level. By combining two existing datasets in a single processing sequence, we take advantage of having different azimuths of acquisition. Key processing methodologies were identified, such as cold water statics correction for compensating variations in the water column, high-definition tomography for building TTI velocity model optimized for both datasets and post-imaging data conditioning for improving the signal-to-noise ratio of the final stack image. This “bi-azimuth” project provides a comprehensive assessment of the potential benefits of multi-azimuth data that will improve pre-salt carbonate reservoir imaging.