The structural evolution of segmented normal faults plays an important role in controlling the stratigraphic development of rift basins. This study investigates the role of fault growth and linkage in controlling the nature of synrift sequences on the hangingwall of the Statfjord East fault, which represents a typical Late Jurassic structure of the prolific Brent Province of the northern North Sea. Well data from Norwegian Blocks 34/7 and 33/9 and detailed 3-D seismic interpretation art used to examine structural and stratigraphic patterns, both along and across fault strike.

The fault system consists of several en echelon segments, which define a series of sub-basins in the hangingwall. Distribution and facies architecture of syn-rift sequences, thickness variations, and the character of internal reflectors are spatially related to the sub-basin geometry. Variations in displacement along the fault segments exhibit characteristics that are typical of mechanically interacting en echelon faults, including local displacement minima and anomalous displacement gradients in regions of segment overlap. Structural and stratigraphic evidence indicate that the Statfjord East fault evolved by the formation and eventual linkage of segments, which are progressively younger towards the north.

Fault evolution is observed to control: 1) shifts in local depocentres that are attributed to the local enhancement of displacement rates resulting from segment interaction; 2) the shoreline migration following segment linkage; and 3) fault scarp degradation, which was most extensive adjacent to the most active section of the fault. Our results imply that knowledge of fault geometry and interaction may allow more accurate detection of subtle, syn-rift reservoirs.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas