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Basin Modelling of the Hammerfest Basin, Norwegian Barents Sea: The Effects of Erosion and Pressure Development on the Distribution of Oil and Gas Accumulations

Jesper K. Nielsen1, Arnt Grøver1, Ane E. Lothe1, Asdrubal Bernal2, Matthias C. Daszinnies1, and Hans M. Helset1
1Basin Modelling Department, SINTEF Petroleum Research, Trondheim, Norway.
2Statoil ASA, Harstad, Norway.

Moderately mature areas of the Norwegian Barents Sea hold several hydrocarbon sites. Successful exploration within additional areas, however, requires a better understanding of the dynamics of petroleum systems. Numerical basin modelling is a useful and efficient tool for investigating the generation, migration, entrapment and leakage of hydrocarbons. The aim of this study was to investigate the effects of different burial histories, with corresponding overpressure development, on the distribution of oil and gas accumulations in the Snøhvit field area of the Hammerfest Basin.

For the burial histories, we used selected depth maps (Late Permian-Present) as input to the palaeobathymetric reconstruction and the associated palaeo-surfaces modelled in SEMI Palaeowater. This was combined with six different sets of erosion estimate maps, which were derived from apatite fission track and vitrinite reflectance analyses. These erosion cases represent different estimated magnitudes of the erosion events at 40-34 and 10-2 Ma. Three of the erosion cases were selected for pressure modelling with the overpressure simulator SEMI Pressim, in which fault traces were used to define pressure compartments of the Stø Formation (Lower-Middle Jurassic). The kinetic model of Ritter et al. (1996, Petroleum Geoscience 2: 133-144) was used to calibrate the source rocks Hekkingen Formation (Late Jurassic) and Kobbe Formation (Middle Triassic) by employing the transformation ratio of kerogen against vitrinite reflectance. The lower burial depth of the Hekkingen Formation makes its thermal maturity more sensitive to the magnitude of erosion.

To explore the effects of overpressure, we tested the different burial histories with and without the pressure modelling integrated, but keeping all other parameters identical. It appears that the development of greater pressure in the deeper buried areas west and north-west of the work area interferes with the flow to the shallower oil and gas accumulations. Integration of pressure modelling can therefore have a major impact in determination of the modelled hydrocarbon column heights. On the other hand, the column heights and the trap geometries may vary in the burial histories by employing different magnitudes of erosion.

This work is a contribution to the project Top seal integrity and leakage, with relevance for exploration risk in the Barents Sea (SIP 186919) funded by The Research Council of Norway.


AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.