Stratigraphic and Structural Interpretation with 3-D Seismic Coherence

Mike Bahorich, John Lopez, Norm Haskell, Susan Nissen, and Alan Poole

3-D seismic discontinuity is useful for identifying faults, stratigraphic features and the relationship between them (Patent pend. Bahorich and Farmer, 1994). This paper covers the application of coherence technology to three basins; the Gulf of Mexico, the North Sea, and the Ardmore Basin of Oklahoma.

In the Gulf of Mexico, 3-D coherence data may be used to simultaneously view faults and stratigraphic features and therefore see the relationship between them. Coherence data reveal channels that avoid a structural high generated by a salt dome, channels that change direction as they cross faults, radial faults adjacent to a salt dome, and complex and en-echelon faults. Since the coherence process is applied to non-interpreted seismic data, these features are available for viewing without the time or bias of interpretation.

Coherence time slices from the Ardmore Basin of Oklahoma were compared with a horizon-dip map and a discrepancy in the fault patterns was noted. Further analysis revealed that subtle errors in the autopicking had created a false bend in a fault trace seen on the horizon-dip map. After correction, the horizon-dip map and coherence time slice indicated similar fault patterns. Since the coherence method is run on the raw seismic data, it provides a view of the faults that is not biased by the interpreter or horizon autopicker.

In the North Sea, faults may exhibit meandering patterns that are easy to interpret on traditional time-slices where they cut perpendicular to stratigraphic bedding but are difficult to recognize where they cut parallel to bedding. The coherence technique images faults in any orientation equally well.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California