4D Tomography at the North Sea

P-663 4D TOMOGRAPHY AT THE NORTH SEA . A. VESNAVER 1 G. DAL MORO 1 G. MADRUSSANI 1 J. PAJCHEL 2 and G. ROSSI 1 1 OGS Borgo Grotta Gigante 42/c 34010 Trieste Italy 2 Norsk Hydro Sandsliveien 90 5020 Bergen Norway Abstract Time-lapse analysis is a proven technology for optimising oil and gas production; similarly 3D tomographic imaging is the proper tool for reconstructing complex structures in depth. Here we combine these two approaches into a consistent processing strategy building a depth model that is time-variant at the reservoir and the seawater (or weathered layer) and constant elsewhere. We