Fault Propagation Folds and Relay Zones and Their Influence on the Distribution of Syn-Rift Sandbodies: Examples from the West Flank of the Oseberg Field, Norwegian North Sea and the Hammam Faraun Fault Block, Sinai, Egypt

By

Stephen Martin Corfield¹, Tom Dreyer², Rob Gawthorpe¹

(1) University of Manchester, Manchester, United Kingdom (2) Norsk Hydro Research Centre, Bergen, Norway

 Fault propagation folds and relay zones and their influence on the distribution of syn-rift sandbodies. Examples from the west flank of the Oseberg Field, Norwegian North Sea and the Hammam Faraun fault block, Sinai, Egypt.

Stephen Corfield¹, Tom Dreyer² and Rob Gawthorpe^{1 1} University of Manchester UK, ² Norsk Hydro Research Centre, Norway.

Recent research in the subsurface of the Norwegian sector of the North Sea has revealed that relay zones and related hangingwall deformation in the form of fault propagation folds have had a major impact on the distribution of synrift sandbodies. These results complement over ten years of fieldwork by the University of Manchester in Sinai. In both areas, the growth and linkage of extensional faults bounding tilted fault blocks during the evolution of the rift basin has resulted in a focussed sand supply to the hangingwall depocentres. The main sediment supply route has been via relay zones. Lateral and vertical growth of faults has also resulted in the development of fault propagation folds and emergent fault block crests.Sands are considered unlikely to be laterally extensive in such a complex setting and the outcrop examples indicate rapid lateral thickness variations in relation to the hangingwall folds. These conclusions are supported by 3D seismic data on the west flank of the Oseberg field in the Norwegian North Sea where Upper Jurassic syn-rfit sand bodies occur in canyons eroded through relay zones. Extensive use of 3D visualisation techniques (formation sculpting, voxel rendering, virtual reality) coupled with seismic modelling has been used to map the geometry and distribution of the syn-rift sandbodies.

The combination of these technologies coupled with the integration of structural and stratigraphic examples from outcrop has lead to an increased understanding of the interaction between fault growth and linkage with the eventual aim of delineating subtle syn-rift plays.