Palaeozoic Core Workshop: Shallow Stratigraphic Cores from the Norwegian Sea Off Helgeland
Force Sedimentology Stratigraphy Group Seminar – Geological evolution of Eastern Greenland: Implications for Hydrocarbon Prospectivity on the Norwegian Continental Shelf.
14 - 15 March 2006 at NPD, Stavanger, Norway
Palaeozoic Core Workshop:
Shallow stratigraphic cores from the Norwegian Sea off Helgeland
- Upper Permian and Lower Triassic reservoir rocks
- Upper Permian hydrocarbon source rocks
- Upper Permian evaporites
Hermann M. Weiss1, Jan Einar Ringås2, Atle Mørk3
1 SINTEF Petroleumsforskning AS, 7465 Trondheim, Norway ()
2 Statoil Forskningssenter, 7005 Trondheim, Norway (); formerly IKU/SINTEF Petroleumsforskning AS
3 SINTEF Petroleumsforskning AS, 7465 Trondheim and NTNU, 7491 Trondheim, Norway ()
Abstract
Stratigraphic drilling in the Norwegian Sea off the Helgeland coast penetrated a 750 m thick, fully marine succession of Upper Permian to Lower Triassic sedimentary rocks which can be compared with rocks exposed onshore in East Greenland. The succession consists of sandstones, turbidites, shales and reworked sabkha sediments. Observations made on these cores contributed to a new, Palaeozoic play model for the mid-Norwegian continental shelf.
Twelve 1-m sections typical of the individual units will be presented and discussed during the workshop. Information on the characteristics of potential source-rocks (a Ravnefjeld Fm. equivalent) and oil staining found in these cores will also be given.
The nearly seven kilometres of core material collected by IKU/SINTEF in 1982 – 1993 are since 2000 in care of the Museum of Natural History and Archaeology (Vitenskapsmuseet) at the Norwegian University of Science and Technology (NTNU) in Trondheim. The NTNU use the material in education and own research, and make it accessible to external academic researchers. SINTEF Petroleum Research continue using the material in their own research and consultant work, and keep cores and results accessible to the oil industry.
Paleo-landscapes of East Greenland: Pathways and barriers for sediment transport.
Ebbe H. Hartz, PGP, Oslo
Niels Hovius, Cambridge University
Sediment transport is guided by the topography of the Earth’s surface. Understanding the paleo-landscape therefore is the key to unraveling how, where and when sediment was supplied to depositional basins. We have studied the paleo-landscape of East Greenland which has supplied sediment to one of the deepest local depositional basins (the Jameson Land basin) during the Devonian to Cretaceous, and as well as the North Atlantic continental shelf. In this study, we have reached beyond the areas with thick sedimentary cover that have been the subject of many previous investigations, and traced paleo-surfaces into adjacent areas with thin or discontinuous cover. There we have found that present and past landscapes share common surfaces. The nature of these surfaces appears to be controlled strongly by the properties of the substrate. For example, in heterogeneous, folded gneisses, resistant rock units constitute topographic highs. In Milne Land, we have found that highs in gneisses first formed at sea level, due to wave cutting of a Jurassic skerry coast. Paleo-islands have been preserved, complete with distinct fossil faunas and sedimentary deposits on the wave and lee side. Where sediments or granites were transgressed, wave beveling was more planar, but locally erosional channels formed. The field data are complemented with regional geologic and topographic data, including new LIDAR data, and satellite imagery. Using these resources, paleo-surfaces were traced up to a hundred km away from the sedimentary successions in which they were first recognized. Some paleo-surfaces are not offset by the faults that are supposed to control the Jameson Land basin. This brings into question the supposed rift origin of the basin. Generally, the Devono-Carboniferous paleo-surfaces are mountainous, whereas the Late Permian and Mesozoic surfaces appear regionally planar and parallel with the exception of channels and faultscarps. The ca. 55 Ma pre-basalt surfaces generally follow the Mesozoic surfaces, but they have more relief. The most distinct surface is a mid Cenozoic sub-horizontal plane, which clearly cuts the older folded surfaces. There is no sedimentary cover on this surface, but it is well documented in cooling ages. Thermochronological data from rocks below older, presently uncovered paleosurfaces indicate that they were once deeply buried, and that thick sedimentary deposits extended far beyond their current limits.
Carboniferous–Permian evolution of the northern North Atlantic and analogies between East Greenland and Norwegian basins
Lars Stemmerik, GEUS
The southern Norwegian Barents Sea – Svalbard –North Greenland area forms the central portion of the east–west oriented northern Pangaean shelf during Carboniferous–Permian time. Integration of onshore geological data and offshore mainly geophysical data has greatly improved our understanding of the evolution of this part of the shelf during Late Palaeozoic time. The depositional evolution of the entire province to a large extent reflects shifts in climate due to the shelf’s northwards drift from approximately 20 N to approximately 45 N palaeolatitude during the Carboniferous and Permian. As a consequence, the region moved from the humid tropical zone in the early Carboniferous through the northern arid zone in the mid-Carboniferous to early Permian, before entering more temperate conditions in the mid-Permian. This long-term latitudinal shift in position and climate clearly affected depositional conditions and resulted in division of the Carboniferous–Permian succession into four clear second order depositional sequences. These sequences reflect long, 15–30 Myr periods of relatively stable depositional conditions separated, at the sequence boundaries by abrupt changes, which can be linked to ongoing rifting of the area, changing oceanographic conditions and the northward drift of the region.
Outcrops in eastern North Greenland form well-exposed analogies to the Barents Sea succession, and the well-exposed Carboniferous–Permian succession in East Greenland provides important information about Upper Palaeozoic facies development offshore mid-Norway.
A review of the Post-Valanginian basin evolution of East Greenland
Whitham, A.G., Kelly S.R.A. and Strogen D.P.
East Greenland north of 70°N preserves a record of Cretaceous sedimentation from the Valanginian to the Campanian. Subsequent to a major reorganisation of fault blocks during rifting in the Volgian-Valanginian a sea floor topography dominated by fault blocks was created and was maintained by faulting until the Mid-Albian. This topography was in filled after the Mid-Albian and a shelf break margin was created and maintained until at least the Campanian. It is possible that there were periods of extension in the Late Cretaceous, but the timing of these movements is poorly constrained. However, it is notable that there was no eastwards progradation of facies belts from the Cenomanian-Campanian.
Post-Valanginian sedimentation was dominated by the accumulation of fine sediments. However, significant thicknesses of coarse clasticsare recorded at several stratigraphic levels. Sandstone deposition is recoded in fluvio-deltaic, tidally influenced shallow marine and deep marine depositional environments. Coarse material was transferred to basinal settings during periods of lowstand, which occurred during the Barremian, Late Aptian, Coniacian, Turonian and Campanian. The primary control on the input of coarse sediment are steps in the basin-bounding fault. This control was maintained after the change in basin floor topography in the Mid-Albian. The cross-rift transfer of sediment is most likely to have occurred after the establishment of a shelf break margin from the Cenomanian onwards.
Petroleum Source Rocks in East Greenland – a Review
Jørgen A. Bojesen-Koefoed, Lars Stemmerik and Flemming G. Christiansen
Geological Survey of Denmark and Greenland (GEUS)
Øster Voldgade 10
DK-1350K Copenhagen
The Upper Palaeozoic – Mesozoic succession in central East Greenland is the most important outcrop analog to understand the stratigraphy and hydrocarbon potential of the offshore basins on the North-East Greenland shelf and other areas in the North Atlantic, including the Norwegian and Barents shelves, and areas near the Faroe Islands.
Onshore East and Northeast Greenland, organic-rich sediments with petroleum source potential have been identified in several stratigraphic levels ranging in age from the Middle Devonian to the Jurassic (Cretaceous). In East and Northeast Greenland, post-Caledonian sediments are exposed from Jameson Land to the south to Store Koldewey to the north. The exposed Devonian–Cretaceous sedimentary succession has a composite thickness of more than 10 kilometres, and seismic data indicate thicknesses in excess of 15 kilometres in the Jameson Land basin. The thermal maturity of the sediments is highly variable, both due to different burial history but also because of regional variations in Tertiary volcanic activity
This presentation summarises the present knowledge on stratigraphy, distribution, quality and geochemical characteristics of eight stratigraphic intervals having petroleum source potential in East andNortheast Greenland.
Basin development of the Danmarkshavn Basin and analogy to the onshore East Greenland basins
Niels. E. Hamann & Lars Stemmerik
DONG, Copenhagen and GEUS, Copenhagen
The East Greenland shelf can be subdivided into a series of tectonic elements, several of which can be linked to plate tectonics features along the North Atlantic margin, thus confirming the pattern known from the Norwegian shelf. Tectonic activity became concentrated towards the centre of the North Atlantic rift system in successive phases, and basin subsidence began to take a NE orientation along the developing continental margin.
A major Upper Palaeozoic salt basin, the Danmarkshavn Basin, located in the north-eastern part of the shelf, was initially controlled by a pre-existing tectonic framework following a N–S trend in East Greenland and along a WNW alignment in North Greenland. Mesozoic rifting reached maximum intensity in the latest Jurassic and continued into the Cretaceous. Following the opening of the Atlantic Ocean in the Early Eocene deposition took place on a subsiding continental margin in a period of post-rift thermal subsidence. Passive margin subsidence was interrupted by at several distinct phases of regional basin margin uplift and inversion, resulting from several different controlling mechanisms.
No wells have yet been drilled on the East Greenland shelf, so no direct stratigraphic correlation of the seismic has been possible; therefore the well-exposed and well-known succession onshore East and eastern North Greenland has been used to calibrate the seismic units.
Evolution of the Late Palaeozoic–Mesozoic rift basin of East Greenland with special emphasis on the Jurassic and Lower Cretaceous syn-rift deposits and their relevance as petroleum system analogues
Finn Surlyk
Geological Institute, Geocenter Copenhagen
University of Copenhagen
Øster Voldgade 10
DK-1350 Copenhagen K
Denmark
East Greenland offers one of the World’s finest field laboratories for the study of siliciclastic rift and thermal contraction basins, their stratigraphy, development, sequence stratigraphy, facies and reservoir properties. The rift basin was initiated in the Late Palaeozoic and the main Mesozoic rift events took place in Early Triassic, Mid Jurassic – earliest Cretaceous ( with a Late Jurassic climax) and in Mid Cretaceous times.
During Late Triassic – Early Jurassic times a thermal contraction basin was formed following earlier phases of rifting. The main reservoir analogues in this basin are:
The Rhaetian–Sinemurian Kap Stewart Group; lacustrine and fluvial – correlative to the Åre and Statfjord.
The Pliensbachian–Lower Bajocian Neill Klinter Group; shallow marine tidally and storm influence – correlative to the Tilje etc., excellent analogue for Heidrunn
In the Mid – Late Jurassic rift basin the main reservoir analogues are:
The Upper Bajocian – Callovian Pelion Formation; shallow sandy backstepping shelf –correlative to Garn, Brent etc.
The Lower – Middle Oxfordian Olympen Formation; the first Jurassic deep-water depositional system with coarse-grained density flow deposits;shelf-slope-basin.
The Upper Oxfordian – VolgianHareelv Formation; probably the World’s finest example of a sedimentary injectite complex – excellent for injectite-dominated fields in the Paleogene of the North Sea and for injectites in general.
The VolgianRaukelv Formation; shows similarities to Troll –coarse-grained shelf margin wedges, extensive high-angle clinoform bedded sheets.
The Volgian–Valanginian Wollaston Forland Group; excellent analogue for the Brae province – proximal marine syn-rift halfgraben fill deposited in thehalfgraben.
A range of coarse clastic deep-water sediments were deposited during a succession of Mid-Cretaceousfaulting and rifting events:
The Mid AlbianRoldBjerge Formation; a chaotic breccia – base of slope and basin
The Upper Turonian – Lower Coniacian Månedal Formation; resedimented conglomerates and sandstones – base of slope and basin
The Lower–Middle Coniacian (?)Vega Sund Formation; sand-rich turbidite basin floor fan.
The three units together serve as excellent analogues for deep-water depositional systems and stratigraphic evolution of the outer Vøring Basin.
The East Greenland rift basin offers the possibility for a wide range of activities of relevance to the oil industry, including:
Study of sand body geometries and dimensions, lateral lithological changes in grain size, sand-shale ratios, connectivity in heteroliths and injectites, sequence stratigraphy and predictability, source rock quality, thickness, lateral extent and stratigraphic occurrence.
The region has a great potential for general field courses and excursion, focused field trips and field studies, training in facies analysis and sequence stratigraphy, comparison of core workshop and log measurements in the field
Geological Setting – East Greenland and Norway.
Perspective- Greenland in the context of exploration and production in Norway.
Harald Brekke, Christian Magnus, Tore Høy, Robert W. Williams
Norwegian Petroleum Directorate
Exploration in the deep water areas in the Norwegian Sea offshore Norway has, since its beginning in 1995, been focussed on the Cretaceous and Palaeocene sequences of the Vøring and Møre basins. Information from the recent years of deep-water exploration drilling and seismic campaigns in the Norwegian Sea continental margin is used to update models for the geological development and the prospectivity of the Norwegian deep-water areas. This includes a better resolution of the tectonic history of the Cretaceous and Tertiary periods, a better understanding of the Early Cretaceous configuration of the Vøring and Møre Basins, and seismic evidence of a Neogene tectonic phase also affecting the early oceanic crust.Towards the end of the Cretaceous the tectonic activity increased and culminated in Mid-Palaeocene accompanied by basin uplift and widespread erosion of basin highs. The Vøring- and Møre Basinswere established by the main rifting episode in the Late Jurassic to earliest Cretaceous and the subsequent Early Cretaceous thermal subsidence. Starting in latest Turonian to earliest Coniacian times, the Vøring Basin was subject to Late Cretaceous block faulting, flank uplift and increased subsidence.TheMøreBasin, situated to the south of the Jan Mayen Lineament, show little evidence of this tectonic activity. Minor discoveries were made in reservoir sands of the Lower and Upper Cretaceous in the eastern flanks of the basins before the deep-water drilling campaign started. In the basins themselves, no well have so far penetrated rocks below the Turonian. However, sandy intervals have been confirmed in the Conaician, Santonian, Campanian and Maastrichtian, as well as in the Lower Palaeocene.
A remarkable turbidite fan system, the Modgunn Fan, is mapped on a 3D survey along the southwestern flank of the Modgunn Arch. The fan is interpreted as belonging to the Tang Formation in Middle Palaeocene. Seismic amplitude interpretation of the Modgunn Fan shows a system with two main feeder channels. Smaller channels are visible inside the main channels. Excellent examples of smaller splays and overbank sediments expelled from the main system can be demonstrated. The thickness of the central part of the channel system is in the range of 120 m. Seismic mapping indicates that two separate channels are amalgamated vertically in the main course of the channel system. The fan pinches out to the east originally as downlap, but is today uplifted on the Modgunn Arch. The sediment transport of the fan system is from South West to North East.
Interpretation of a few 2D lines westwards from the Modgunn Fan shows that the turbidite fan and channels are fed from a delta on the Møre Marginal High only 15 km from the main submarine fan. The delta is developed with nice clinoforms and topsets and shows the delta front and the pinching out of the delta into the marin basin. There is also indication of erosion and slidingat the uppermost and youngest part of the delta front. The Clinoforms indicate a transport direction from West / Southwest Provenance studies show that a major part of the Cretaceous western and central basin fill is derived from East Greenland, whereas minor contributions from the Norwegian mainland are seen in deposits along the eastern basin flanks. The distribution in time and space of these sand deposits is complex and further exploration calls for improved sedimentological models. Bio-stratigraphic studies of the late Cretaceous and lower palaeocene re-sedimentation history of the Vøring and Møre Basins reveals a period of un-roofing of the Cretaceous to Permian sequences in the hinterland. The conspicuous absence of any Jurassic spores in the re-sedimentation record and the enormous volumes of Cretaceous sediments present put clear constraints on models for the hinterland palaeography and the Cretaceous plate tectonically related uplift history of the surrounding areas, including Greenland, the Barents Sea Shelf and Fennoscandia, and hence the distribution of possible reservoir sands. To date several gas discoveries and one oil discovery are made within the deep basin areas. The hydrocarbons are probably generated from both Jurassic (gas) and Cretaceous (oil) source rocks. Well data indicate possible source rock intervals in the both Lower and Upper Cretaceous of the basins and their eastern flanks but a good quality source rock of Cretaceous age is still to be confirmed. In-house analyses of the state of oxidation of Cretaceous shales indicate local favourable environment for the development of Cretaceous source rock within the basin setting. The NPD play models of the Cretaceous and Lower Palaeocene of the Vøring and Møre Basinsare updated according to the latest well information of the area.