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SINTEF Petroleum Research
Contact:
Maik Inthorn
SINTEF Petroleum ResearchNO-7465 Trondheim
Norway
www.sintef.com
Structural map of the Norwegian Sea (after Blystad et al., 1995)
Geoseismic section through the working area(modified from Swiecicki et al.,1998)
Norwegian M
ainland
East Gre
enland
Helgeland B.
Nordland R.
Dønna T.
Halten T.
Froan B.
Helland H
ansen A
rchVigrid
Syncline
Vøring M
arginal H
igh
Utgard
H.
Norwegian M
ainland
East Gre
enland
Helgeland B.
Nordland R.
Dønna T.
Halten T.
Froan B.
Helland H
ansen A
rchVigrid
Syncline
Vøring M
arginal H
igh
Utgard
H.
average HI in calibration wells
average TOC in calibration wells
Norwegian Mainland
East Greenland
Helgeland B.Nordland R.
Dønna T.
Halten T.
Froan B.
Helland Hansen ArchVigrid Syncline
Vøring Marginal High
N
Utgard H.
Source Rock potential poor
fair
good
very good
(Peters, 1986)
Modelling results for VMH highly dependent on palaeo-water depth
On morphological highs:• Low thickness or even absence
(low sedimentation /winnowing)• Strongly varying TOC over small
lateral distances (terrigenous input)
• Low HI (little marine OM, oxic bottom water)
Increasing potential with increasing distance to coast
In the basins:• high source rock
potential• dominance of marine
organic matter• good preservation of OM
in anoxic bottom waters
Conclusions∗ Our modelling results indicate very good source rock potential of the Spekk Fm over large
parts of the Vøring Basin area (5-7 wt% TOC, HI of 250-300 mgHC/gC)
∗ Distribution and quality of the source rock are highly dependent on paleo-water depth
∗ In the basins, organic matter of marine origin dominates, but the overall volume of high quality source rock is limited as primary production and sedimentation rates are low
∗ At morphological highs already existing in the Jurassic, potential is reduced (2-4 wt% TOC, HI of 100-200 mgHC/gC) because of high content of terrigenous organic matter. Current and wave action provide good oxygenation reducing preservation of organic matter
∗ Special local patterns of sediment input (rivers) and transport close to the coast of the Norwegian mainland and the local highs resulted in rather strong variation in source rock quality over small lateral distances and can not be matched by the model
∗ In anoxic bottom water conditions comparatively low marine primary production (50 to 100 gCm-2yr-2) is sufficient to support high organic matter content and hydrocarbon potential of the sediments as preservation is rather good.
ReferencesBlystad, P., Brekke, H., Færesth, F.B., Larsen, R., Skogseid, J., Tørudbakken, B., (1995) Structural elements of the Norwegian continental shelf. In: NPD-Bulletin, 8, pp.
45. The Norwegian Petroleum Directorate, Stavanger.Brekke, H., (2000) The tectonic evolution of the Norwegian Sea continental margin with emphasis on the Vøring and Møre Basins. In: A.e.a. Nøttvedt (Ed.), Dynamics
of the Norwegian margin, 167, Geol. Soc. Spec. Publ. (Ed. by A.e.a. Nøttvedt), pp. 327-378. Geological Society, London.Peters, K.E., (1986) Guidelines for evaluating petroleum source rock using programmed pyrolysis. The American Association of Petroleum Geologists Bulletin, 70(3),
318-329.Swiecicki, T., Gibb, P.B., Farrow, G.E., Coward, M.P., (1998) A tectonostratigraphic framework for the Mid-Norway region. Marine and Petroleum Geology, 15, 245-276.Torsvik, T.H., Carlos, D., Mosar, J., Cocks, L.R.M., Malme, T., (2002) Global reconstructions and North Atlantic palaeogeography 440 Ma to Recent. In: E.A. Eide (Ed.),
BATLAS – Mid Norway plate reconstructions atlas with global and Atlantic perspectives (Ed. by E.A. Eide), pp. 18-39. Geological Survey of Norway.
Palaeogeographical situation during the Late Jurassic (150 Ma)(modified from Torsvik et al., 2002)
Norwayworking area
1SINTEF Petroleum Research, Trondheim, Norway; 2 now at Statoil ASA, Stjørdal, NorwayMaik Inthorn1, Janine Zweigel2, Ute Mann1
3D Source Rock Modellingof the Late Jurassic Vøring Basin off Mid-Norway
An underexplored petroleum provinceThe greater Vøring Basin off mid-Norway, close to the well established petroleum plays of the Dønna and Halten Terraces, has high potential for petroleum prospectivity. It remains under- explored, although several discoveries of mainly gas but also oil were made in the last few years. One important risk-factor for the area is the presence or absence of an effective source rock.
Well data collection and interpretation∗ No well ever reached Late Jurassic rocks in the deeper Vøring Basin
∗ Therefore, well data from the eastern and western margin of the Jurassic rift zone (Halten Terrace, Dønna Terrace, Trøndelag Platform, East Greenland) were analysed
∗ Data from 28 wells in the Norwegian Sea comprising 1077 Spekk Fm samples were compiled
Spekk Formation source rock∗ Equivalent to the Kimmeridge Clay and Draupne formations of the North Sea
∗ Only source rock off mid-Norway proven capable of generating significant quantities of oil
∗ Covered by 9000 to 13000 m of Cretaceous and Tertiary sediments in the central parts of the Vøring Basin (Brekke, 2000) -> overmature
∗ Higher chances for prospectivity suggested at local highs and at the western flank of the basin where the overburden is less - but there covered by Tertiary lava drapes and invisible to seismic
There is no direct information on quality and distributionof the Spekk Fm in the deeper Vøring Basin available
0
50
100
150
200
250
0-1 1-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 9-10 >10
TOC (%)
Num
ber o
f Sam
ples
020406080
100120140160180200
0-50
50-10
0
100-1
50
150-2
00
200-2
50
250-3
00
300-3
50
350-4
00
400-4
50
450-5
00
500-5
50
550-6
00>60
0
Hydrogen Index (mg HC/g TOC)
Norwegian Sea
average: 6.18 wt% TOC
Norwegian Sea
average HI: 283 mgHC/gC
High source rock potential
∗ Τhe Late Jurassic rift zone between Norway and Greenland represented a marine basin with anoxic deep waters and deposition of organic matter rich clays
∗ Input of terrigenous organic matter is significant as indicated by bulk organic, maceral and biomarker data
∗ Kerogen composition and petroleum potential of the Spekk Fm vary significantly over short lateral distances
∗ Most samples from the Spekk Fm. represent a mixture of type II and type III kerogens
∗ High content of pyrolytically “dead” organic carbon (inertinite)
∗ The results indicate that the eastern part of the Norwegian Sea represented a shallow shelf environment
Organic facies modellingWe apllied SINTEF’s process-based source rock modelling tool OF-Mod 3D to form a spatial picture of TOC and HI distribution during the Late Jurassic in the entire rift area between mid-Norway and East Greenland. Based on the data interpretation, a detailed palaeo-water depth reconstruction, structural and seismic information and general process-understanding a 3D model was developed, on which several conceptual settings were tested.
∗ Generally good fit of modelled TOC and HI with the calibration data
∗ Some strong deviations close to morphological highs because of local patterns of organic matter input and distribution with currents
AcknowledgementsThis work is part of the Vøtec project (”Tectonic development and temperature history of the Vøring area, mid Norway”). The project is supported by Statoil, Shell, and the Norwegian Research Council. We thank Christof Keuser from Shell for provision of data.
