Reconstructing
the Growth History of a
Kane, Karla E.1, Eirik Larsen2, Christopher A.L. Jackson3,
Anna Sofia Gregersson4 (1) Imperial College, London, United Kingdom
(2) Statoil ASA, Stavanger,
Norway (3) Imperial College, (4) Statoil ASA,
In the Sleipner
area of the South Viking Graben, salt tectonics and
the growth of normal faults combined to form a series of interconnected
sub-basins into which deep-water sediments were deposited in late syn-rift times. Reconstructing the tectono-stratigraphic
history of this structurally complex area is critical in assessing the
potential for deposition of deep-water, sand-prone reservoir intervals within
the largely unexplored Upper Jurassic syn-rift
succession.
Mapping of key seismic horizons allows
the syn-rift succession to be sub-divided into two
major seismic-stratigraphic units that document
tectonically-controlled changes in depocentre location
and size. Within and between individual sub-basins the lowermost syn-rift interval thins towards salt-cored highs, revealing
a period of syn-depositional diapirism.
The uppermost syn-rift interval displays significant
spatial variations in thickness which are related to
both ongoing diapirism and newly active normal
faults.
Biostratigraphic and wireline
data on structural highs that flank the sub-basins suggest that periods of
erosion on these highs correspond to expanded, possibly sand-prone, intervals
within the basin-fill succession. Although no well data is available within the
basin-fill itself, the identification of an unconformity within the uppermost syn-rift interval may reflect gravity-flow-related
submarine erosion associated with “fill-and–spill” of sediment between
component sub-basins. Seismic attribute analysis provides supporting evidence
for the existence of such a system.
Preliminary results predict
structurally-confined sandbodies within the Sleipner sub-basins, sourced from the basin-margin and
deposited in an axial turbidite lobe system. There is
also potential for a series of smaller slope apron systems, sourced from the
uplifted footwalls of active normal faults.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California