Print this pageA Revised Hypothesis for the Structural Evolution of the
East Brae Region of the 
South
Viking Graben, North Sea
BROWN, M. A., M. P. COWARD, P. ALLEN, and S. BUCKNER
Three Dimensional visualisation and modelling of the East Brae field, South
Viking Graben, has allowed complete revision of the structural evolution of the
area. The area is one of well documented inversion at the end Cretaceous.
Initial 3D visualisation provides a much clearer picture of these structures
than seismic interpretation packages.
The footwall of the South Viking Graben
is kinked at the junction between the
original extensional fault, the Western boundary Fault (WBF) and the erosion
surface above. Fault bend folds are produced as the hanging wall moves over this
kink during inversion. The forelimb dip of these folds indicates the amount of
steepening which the WBF underwent during inversion. This fault has been rotated
to its pre-inversion orientation and contoured providing valuable information
about sources and directions of sediment input into the basin. Forward modelling
using this rotated fault surface has reproduced the inversion structures which
are clearly seen on the seismic sections. This forward modelling method allows
an accurate and rapid assessment of the fault geometry, particularly at depth
where seismic resolution is poor, and of the movement directions, displacement
values, and shear vectors, necessary in the hanging wall.
This allowed revision of the basic model within the limits imposed by the original seismic data until an accurate hanging wall was modelled; these values were then applied to restoration of the real data set. Additional factors have been included in the forward modelling to study strain within the hanging wall to aid prediction of the geometry and density of fracture sets.