- Copyright © 2001 Society of Exploration Geophysicists
Despite the success of 3-D seismology, the geophysical community recognizes that these surveys contain more information than simply the structure or identification of isolated bodies in the subsurface. This conviction has led to new techniques to exploit the additional information. Amoco's development of coherence cube technology in the 1990s is an example. At about the same time, based on work by Roy Lindseth originally done in the 1970s, a plethora of 3-D poststack inversion algorithms arrived that delivered high-resolution information about the subsurface from seismic data.
This paper describes the integration of coherence cube imaging and seismic inversion and the advantages that accrue from this combination.
Coherence cube imaging essentially generates a cube of coherence coefficients by calculating localized waveform similarity in both in-line and cross-line directions. The underlying assumption is that seismic traces cut by a fault generally have different seismic character than neighboring traces. As a result, there is a sharp discontinuity in local trace-to-trace “coherence.” Similarly, stratigraphic features are associated with definite seismic waveform expressions. A time slice from a coherence cube would depict lineaments of low coherence along faults and other features like channels, reefs, salt edges, and unconformities.
Traditional seismic time slices are usually used for interpreting faults that run perpendicular to strike. However, in complex fault zones, faults running parallel to strike become more difficult to see as fault lineaments become superimposed on bedding lineaments. Because three-dimensionality is an essential ingredient of the coherence cube, faults or fractures in any orientation are revealed equally well. Radial and en-echelon faulting also are seen clearly. Furthermore, because features such as beaches and deltas are clearly defined by coherence cube, a better idea of progression and retreat is possible while trying to reconstruct the sequence stratigraphy of the area. Similarly, the remarkable detail of mud flows, submarine …