ИСТИНА

2-D/3-D seismic attribute mapping is a widely-used tool to extract geo-morphological, structural, stratigraphical and reservoir properties information from seismic data. These geometric, kinematic, dynamic and statistical measures allow revealing a better qualitative (sometimes quantitative) interpretation. One of the advantages of this approach is to illustrate subtle features, which shows no evidence on conventional seismic images. However, it is difficult to choose ‘the right attributes' in specifically carbonate depositional environment, from a pool of seismic attributes stemmed from different mathematic algorithms. Here we present some case studies, which show that by using seismic attribute mapping, the evolution of lateral extension of carbonate buildup complexes in 3-D can be reconstructed. What's more, some subtle features are illustrated when the ‘right attributes' are chosen, such as the organization of karsification and of subtle shoal build up. Based on these cases studies, a seismic attributes ranking for the carbonate depositional environment is proposed in order to establish a list of a prior attributes to be computed at the exploration stage. Concerning to our observations, different attributes are easily associated to some specific geological objects. For example, kartification is more visible on coherency maps. Clinofrom and progradations are visible for time slices or horizon slices. Subtle shoal buildups can be highlighted by a neural classification method and reflector convergence (3-D process of dip integration attribute applied on each seismic trace in order to highlight stratigraphical limits). Low frequency component in spectral decomposition can provide some coherent noise out of the zone of interest while the main frequency does not. Basically the reliability of the seismic attribute is also based on the quality of seismic data. When dealing with noisy data and hunting for a laterally subtle facies change, a reconditioning processing (for example anti-noise and/or dip-driven filter) should be done for the dataset firstly to have meaningful attribute maps. In conclusion, by investigating the texture of the seismic data from selected volumetric, surface and interval seismic attributes, the geomorphology, stratigraphic information and reservoir properties can be revealed and illustrated in carbonate depositional environment, taking into account of course the limitations of seismic resolution and data quality.