Velocity Analysis for the Faroese GlyVeST Data–Merits of Multiple Attenuation – 3D Visualization and CRS Processing

Velocity analysis is one of the most important and critical aspects of seismic processing. It involves picking of optimal velocity functions on a predefined analysis grid, which is a time-consuming and laborious task. Whilst velocity picking is quite simple in principle, implementation proves to be a great deal more complicated, for numerous reasons, such as: the presence of multiples, poor signal-to-noise ratios, limited offset ranges, etc. Due to these difficulties, velocity analysis remains the phase in which the most human intervention occurs. A great deal of effort has been devoted toward reducing the time spent and increasing the accuracy of this crucial stage, either by better conditioning of the data for velocity analysis or through the development of highly interactive graphics software to aid in velocity picking. In this paper, we highlight the merits of multiple attenuation and 3D visualization, as well as common-reflection-surface processing, to the velocity analysis of the GlyVeST seismic data. A good multiple-attenuation scheme conditions the data for velocity analysis, while 3D visualization helps to provide better facilities for velocity picking and speed up this laborious task. Finally, common-reflection-surface processing overcomes the problems of limited offset range and poor signal-to-noise ratio, characteristic of the GlyVeST data.