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Looking for Seismic Facies Expression of Fault and Related Deformation Zones in 3-D Seismic Volumes


Mapping and understanding distributed deformation is a major challenge for the structural interpretation of seismic data. Conventional workflows for seismic interpretation commonly represent faults as discrete planar discontinuities across which stratal reflections are offset (Brown, 2001). Although this approach can greatly facilitate the creation of maps of stratal surfaces and hence the formulation of seismic stratigraphic models, this simplification can hamper understanding of subsurface structural geology. We show here that volumes of seismic signal disturbance with low signal/noise ratio are systematically observed within 3D seismic datasets around fault systems. These seismic disturbance zones (SDZ) are commonly characterized by complex perturbations of the signal and occur at the sub-seismic to seismic scale. They may store important information on deformation distributed around those larger scale structures that may be readily interpreted in conventional amplitude displays of seismic data scale. We introduce a method to detect fault-related disturbance zonesand to discriminate between this and other noise sources such as those associated with the seismic acquisition (footprint noise). Two case studies, from the Taranaki basin and deep-water Niger delta are presented. These resolve structures within SDZs using tensor and semblance attributes along with conventional seismic mapping. We shows that, through seismic image processing and the use of cross-plot functions, it is possible to extract SDZs, to treat them as geobodies and explore their internal seismic texture. A seismic image processing workflow to map the signal properties within the fault SDZ and reconstruct unsupervised seismic facies by using cluster analysis methods is proposed.