A 3D seismic dataset of exceptionally high quality has been used to study the geometry and evolution of normal fault zones in the Mesozoic of the U.K. southern North Sea. Such data provides a complete three-dimensional picture of fault geometries and linkages from a few metres to hundreds of metres scale and can be used to assess fault growth and segmentation as input for fault modelling in hydrocarbon reservoirs. The resolution of this data enables the measurement of displacements down to ca. 5 m. The level of complexity of the fault zones can be related to their tectonic history, the geometry at their tips and to the proximity of other major faults. Individual fault segments that would not normally be recognized can be identified and characterized with the aid of seismic attribute maps. Displacement-distance profiles have an overall elliptical form, but with a highly irregular geometry superimposed. Displacement gradient data show fault growth has occurred by the linkage of a heirarchy of fault segments of different gradients. Short (ca. 375 m), primary fault segments with steep displacement gradients are interpreted to have propagated towards one another and linked to form longer (ca. 3 km), lower displacement gradient segments. Displacement vs. strike length measurements for these faults are scattered, which also implies that fault growth has occurred by segment linkage and propagation over a hierarchy of length scales, rather than by radial tip line propagation. This correlates with previously published data from different scales and tectonic settings.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah