The Effect of Improved
Palaeobathymetry Estimation in Hydrocarbon Migration
Modelling
By
Tomas Kjennerud1, Oyvind Sylta1, Martin Hamborg1, Stein Tore Wien1
(1) SINTEF Petroleum Research, Trondheim, Norway
Palaeobathymetry is a crucial input in the modelling of hydrocarbon
migration
through geological time, as even small changes in the basin morphology
may affect the amount of trapped hydrocarbons. Commonly, palaeo-water depth in
basin models is either ignored or treated as a flat surface with fixed water
depth. Considerations of 2D or 3D bathymetry though geological time are rare.
Palaeobathymetry is in the present work estimated in 3D by combining relevant
information from depositional geometries, sedimentological indicators of shallow
or zero water depth and micropalaeontological interpretation from cores and
cuttings. In addition, decompaction and flexural isostasy are accounted for.
Several tests on data from the Norwegian continental shelf have been carried out
in order to quantify the significance of palaeobathymetry in modelling. In each
test a separate scenario was carried out, whereby palaeobathymetry was ignored.
It has been shown that constrained palaeobathymetry may change the hydrocarbon
migration
direction through geological time, indicating that both the
hydrocarbon fill history and phase trapping history will be different. There are
no easy way of determining which hydrocarbon traps in a basin that are sensitive
to palaeobathymetric input and which are not, except for modelling the whole
system.