Instantaneous attributes: the what and the how

Since their introduction by Nigel Anstey and Tury Taner in the 1970s, attributes have become an integral tool in the interpreter's arsenal. At present, as emphasised by Taner, no direct relationships have been established between all attributes and physical and geological characteristics of the subsurface. Their discriminatory properties, however, allow very useful classifications to be performed. This paper deals with various attribute-related issues. First, we consider the theoretical and physical aspects concerning instantaneous attributes, particularly instantaneous phase. This attribute is of central importance since it describes the location of events in the seismic trace and leads to the computation of other instantaneous quantities. Second, we deal with the issue of information content. It has often been implied that attributes convey no more information than that present in the original seismic trace from which they are derived. This, however, is akin to claiming that David contains no more information than the raw marble from which Michelangelo freed him. A seismic attribute section provides that much more information. The attribute in time attempts to enhance resolution, whereas the attribute property in the spatial dimension emphasises continuity. These important and interesting issues will be dealt with theoretically and by example. Finally, we present and illustrate by synthetic and real data examples, a novel, hybrid attribute which has been constructed to provide high resolution information. We must point out that, as is always the case, our attribute is dependent on the phase of the source wavelet.