Gravity-Gradient Data Integrated in Pre-Stack Depth Migration in the Southern North Sea

IG-3 GRAVITY-GRADIENT DATA INTEGRATED IN PRE-STACK DEPTH MIGRATION IN THE SOUTHERN NORTH SEA Summary 1 Shell U.K. Exploration and Production have acquired gravity-gradient data in the Southern North Sea to aid velocity/depth model building for pre-stack depth migration (PreSDM). Gravitygradient data has higher resolution than conventional gravity data (typically 600 m versus 3 km). Rather than validating the model after a full-blown volume migration the data have been incorporated into the loop of iterative PreSDM using linear relationships between layer velocities and densities derived at well positions. The difference between the gravity-gradient field measurements and the model response has been