3D MAZ Anisotropic Depth Imaging on Goliat Field

The objective of the Multi Azimuth Anisotropic Pre Stack Depth Migration (APSDM) project on the Goliat field was to generate a seismic data set that allowed a more reliable interpretation of the reservoirs, the exploration targets, the structural trends and fault pattern in a complex area where the illumination represents the main issue. To achieve such goals the adopted strategy was to produce a unique velocity volume honouring the 3 azimuths simultaneously by means of a multi-azimuth-anisotropic-grid tomography applied with a layer based strategy. The workflow was applied by integrating all the available geological and geophysical information: dense residual moveout auto-picking, dip attribute, interpreted seismic horizons, sonic logs. The final APSDM volume significantly improved the seismic image quality as compared to the time migrated volume: better continuity of the reflectors and fault planes resolution are the most important results achieved, with a more consistent picture of the sub-surface and the recovery of the distortions due to fault shadows. Thanks to the accurate velocity analysis that exploits all the information coming from the MAZ survey it is possible to state that the APSDM volume clarified a lot the structural assets of the target area.