The Importance of Paleozoic Petroleum Source-Rocks in the Norwegian Barents Sea: Insights from Basin Modeling Using Monte Carlo Simulation Techniques

M. C. Daszinnies¹, M. Inthorn¹, U. Ritter¹, H. M. Weiss¹, J. K. Nielsen¹, and A. Tømmerås^2
1SINTEF Petroleum Research, NO-7465 Trondheim, Norway
²Migris AS, PO Box 1273, Pirsenteret, NO-7462 Trondheim, Norway

The Norwegian Barents Sea has been regarded as mainly gas-prone since the earliest drilling campaigns in the 1980s. More recently, the oil discoveries of the Goliat and Nucula structures shed new light on these traditional considerations. They strongly highlight the oil potential of the Norwegian Barents Sea region and indicate the need for revised exploration models.

Traditionally, mainly Mesozoic source rocks of Triassic and Jurassic ages have been taken into consideration to explain the petroleum entrapments found in the Mesozoic carrier units. However, biomarker and isotope signatures of oil samples from the Barents Sea often suggest mixed oil sources. The latter are not always consistent with Mesozoic source rocks alone and rather point towards older, Palaeozoic source contributions (Ohm et al. 2008). This and the limitation of thermally mature Jurassic sources to the western Barents Sea ask for the incorporation of Palaeozoic sources into revised exploration models.

In this study, we focused on the southern part of the open Barents Sea area. We aimed to investigate the significance of hydrocarbon contributions from a Palaeozoic source onto petroleum migration routes and entrapment in a Mesozoic carrier system within regional basin model. A complex 3D basin model has been constructed including the subsidence and uplift history, source-rock formation, thermal evolution, maturation of kerogen, expulsion from source rocks and migration of expelled petroleum. Secondary migration processes were simulated using SINTEF’s in-house basin modelling tool SEMI (Sylta 2004). Monte Carlo simulation techniques were employed by us in order to account for uncertainties intrinsic to the incorporated processes. Exemplary, we will present quantitative uncertainty estimates on present-day trap fillings in the Jurassic Stø Formation due to hydrocarbon charges via fault leakage from the Late Permian Ørret Formation source rock.

References

Ohm SE, Karlsen DA, Austin TJF (2008) Geochemically driven exploration in uplifted areas:Examples from the Norwegian Barents Sea. AAPG Bulletin 92: 1191-1223.

Sylta Ø (2004) Hydrocarbon migration modelling and exploration risk. Doctoral Theses at NTNU 2004:145. Norwegian University of Science and Technology, Trondheim, Norway.

AAPG Search and Discovery Article #90091©2009 AAPG Hedberg Research Conference, May 3-7, 2009 - Napa, California, U.S.A.