Application of Fully Integrated Quantitative Basin Analysis Model: Oseberg Area, Norwegian North Sea
Birger Dahl, Egil Nysaether, C. Gordon Speers, M. Arif Yukler
A new deterministic dynamic basin model was developed to quantify basin evolution in terms of geologic, hydrodynamic, geothermal, and geochemical histories. Quantification of the processes occurring in sedimentary sequences was based on series of equations defining fluid flow, grain velocity, conductive and convective heat flow, maturation of organic matter, isomerization of steranes and hopanes, hydrocarbon generation, and potential migration directions.
One-dimensional studies on 12 wells were used to optimize (1) the conceptual model in terms of tectonic history, basin formation, stratigraphy, lithology, paleoclimate, and paleodepositional environments and (2) the parameters of the equations used. Two-dimensional studies were undertaken on three seismic profiles from the region. The model results were checked against all the available data on geology, hydrodynamics, geothermics, seismics, and geochemistry.
The modeling results showed that the crust was not thinned much, contrary to the amounts cited in literature. The maximum amount of heat flow was 1.20 heat-flow units (HFU) during Late Jurassic. The heat flow steadily decreased, reaching a value of 1.0 HFU at the beginning of the Cretaceous. A slight increase in heat flow during middle to late Eocene was computed. Petroleum generation started 66 Ma and continued at different rates until the present. Petroleum then migrated eastward and southward into the Oseberg structures. The modeling results indicated two major petroleum types in the area. All the modeling results have been confirmed by geochemical data in terms of pyrolysis, biomarkers, and isotopes.
AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.