Generation and origin of natural gas in Lower Palaeozoic shales from southern Sweden

1969 ◽  
pp. 37-40
Author(s):  
Niels Hemmingsen Schovsbo ◽  
Arne Thorshøj Nielsen
Keyword(s):  
Source Rocks ◽  
Southern Sweden ◽  
Hydrocarbon Gases ◽  
Biogenic Gas ◽  
South Central ◽  
Alum Shale ◽  
Marine Source ◽  
Lower Palaeozoic ◽  
Background Gas ◽  
Origin Of Natural Gas

The Lower Palaeozoic succession in Scandinavia includes several excellent marine source rocks notably the Alum Shale, the Dicellograptus shale and the Rastrites Shale that have been targets for shale gas exploration since 2008. We here report on samples of these source rocks from cored shallow scientific wells in southern Sweden. The samples contain both free and sorbed hydrocarbon gases with concentrations significantly above the background gas level. The gases consist of a mixture of thermogenic and bacterially derived gas. The latter likely derives from both carbonate reduction and methyl fermentation processes. The presence of both thermogenic and biogenic gas in the Lower Palaeozoic shales is in agreement with results from past and present exploration activities; thermogenic gas is a target in deeply buried, gas-mature shales in southernmost Sweden, Denmark and northern Poland, whereas biogenic gas is a target in shallow, immature-marginally mature shales in south central Sweden. We here document that biogenic gas signatures are present also in gas-mature shallow buried shales in Skåne in southernmost Sweden.

South-Central Barents Sea Composite Tectono-Sedimentary Element, offshore Norway and Russia

2021 ◽  
pp. M57-2017-42
Author(s):  
A. G. Doré ◽  
T. Dahlgren ◽  
M. J. Flowerdew ◽  
T. Forthun ◽  
J. O. Hansen ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Barents Sea ◽  
Source Rocks ◽  
Novaya Zemlya ◽  
South Central ◽  
Marine Source ◽  
Basement High ◽  
Shallow Marine Sediments ◽  
Clastic Reservoirs ◽  
Near Future

AbstractThe south-central Barents Sea today comprises a shallow continental shelf with water depths mainly in the 200-400m range, straddling the Norway-Russia marine boundary. Geologically it consists of a stable platform (the Bjarmeland Platform), dissected by rifts of probable Late Carboniferous age, with a significant and geologically persistent basement high (the Fedynsky High) in its south-eastern part. The rifts are the ENE-WSW trending Nordkapp Basin, the similarly-trending but less clearly demarcated Ottar Basin, and the NW-SE Tiddlybanken Basin. The varying rift trends appear to reflect the orogenic grain patchwork of the basement (Caledonide and Timanide), and these basins were infilled with a variable facies assemblage including substantial Carboniferous-Permian halites.Massive sedimentary influx of fluvio-deltaic to shallow marine sediments took place in the Triassic, from the E and SE (Urals, Novaya Zemlya and western Siberia) and south (Baltic Shield), resulting in doming and diapirism in the areas of thickest salt, particularly in the rifts. The succeeding Jurassic, Cretaceous and Cenozoic successions are generally thin, locally thickening in rim synclines and in the NE of the area towards the deep basins flanking Novaya Zemlya. Reactivation of the halokinetic structures took place in the early Cenozoic, probably associated with the development of the NE Atlantic-Arctic Ocean linkage.Marine source rocks of Triassic and Late Jurassic age are present in the area, along with Carboniferous and Permian source rocks of uncertain effectiveness. Petroleum has been found in Jurassic and Triassic clastic reservoirs, including recent shallow Jurassic oil and gas discoveries. Although none are currently in production, near-future oil development is likely in Wisting discovery, on the western margin of the area. New exploration, including drilling, is currently taking place in the east of the area as a result of recent Norwegian and Russian licensing.

Hydrothermal activity in the Upper Permian Ravnefjeld Formation of central East Greenland – a study of sulphide morphotypes

1998 ◽  
pp. 81-87
Author(s):  
Jesper Kresten Nielsen ◽  
Mikael Pedersen
Keyword(s):  
Base Metal ◽  
Early Period ◽  
Sedimentary Basins ◽  
Hydrothermal Activity ◽  
Source Rocks ◽  
Upper Permian ◽  
Thermal Activity ◽  
East Greenland ◽  
The North ◽  
Alum Shale

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Kresten Nielsen, J., & Pedersen, M. (1998). Hydrothermal activity in the Upper Permian Ravnefjeld Formation of central East Greenland – a study of sulphide morphotypes. Geology of Greenland Survey Bulletin, 180, 81-87. https://doi.org/10.34194/ggub.v180.5090 _______________ Bituminous shales of the Ravnefjeld Formation were deposited in the subsiding East Greenland basin during the Upper Permian. The shales are exposed from Jameson Land in the south (71°N; Fig. 1) to Clavering Ø in the north (74°20′N) and have attracted considerable attention due to their high potential as hydrocarbon source rocks (Piasecki & Stemmerik 1991; Scholle et al. 1991; Christiansen et al. 1992, 1993a, b). Furthermore, enrichment of lead, zinc and copper has been known in the Ravnefjeld Formation on Wegener Halvø since 1968 (Lehnert-Thiel 1968; Fig. 1). This mineralisation was assumed to be of primary or early diagenetic origin due to similarities with the central European Kupferschiefer (Harpøth et al. 1986). Later studies, however, suggested base metal mineralisation in the immediately underlying carbonate reefs to be Tertiary in age (Stemmerik 1991). Due to geographical coincidence between the two types of mineralisation, a common history is a likely assumption, but a timing paradox exists. A part of the TUPOLAR project on the ‘Resources of the sedimentary basins of North and East Greenland’ has been dedicated to re-investigation of the mineralisation in the Ravnefjeld Formation in order to determine the genesis of the mineralisation and whether or not primary or early diagenetic base metal enrichment has taken place on Wegener Halvø, possibly in relation to an early period of hydrothermal activity. One approach to this is to study the various sulphides in the Ravnefjeld Formation; this is carried out in close co-operation with a current Ph.D. project at the University of Copenhagen, Denmark. Diagenetically formed pyrite is a common constituent of marine shales and the study of pyrite morphotypes has previously been successful from thermalli immature parts of elucidating depositional environment and thermal effects in the Alum Shale Formation of Scandinavia (Nielsen 1996; Nielsen et al. 1998). The present paper describes the preliminary results of a similar study on pyrite from thermally immature parts of the Ravnefjeld Formation which, combined with the study of textures of base metal sulphides in the Wegener Halvø area (Fig. 1), may provide an important step in the evaluation of the presence or absence of early thermal activity on (or below) the Upper Permian sea floor.

scholarly journals Palaeozoic tectonic and sedimentary evolution and hyrdrocarbon prospectivity in the Bornholm area

1994 ◽  
Vol 34 ◽  
pp. 1-23
Author(s):  
Ole Valdemar Vejbæk ◽  
Svend Stouge ◽  
Kurt Damtoft Poulsen
Keyword(s):  
Late Cretaceous ◽  
Foreland Basin ◽  
Fault System ◽  
Structural Development ◽  
The South ◽  
Alum Shale ◽  
Present Distribution ◽  
Lower Palaeozoic ◽  
Wrench Fault ◽  
Uplift And Erosion

The present distribution of Palaeozoic sediments in the Bornholm area is a consequence of several different tectonic regimes during the Phanerozoic eon. This development may be divided into three main evolutionary phases: A Caledonian to Variscian phase encompassing the Lower Palaeozoic sediments. The sediments are assumed originally to have showed a gradual thickness increase towards the Caledonian Deformation Front located to the south. This pre-rift development may be further subdivided into three sub-phases: A period of slow sedimentation on a relatively stable platform as recorded by the uniformly low thicknesses of the Cambrian to Lower Silurian sediments. A period of foreland-type rapid sedimentation commencing in the Llandoverian to Wenlockian, continuing in the Ludlovian and possibly into the Devonian. The period is characterized by /olding and uplift of the Caledonides to the south causing tectonic loading of the foreland and resultant rapid sedimentation in the foreland basin. A period of gravitational collapse causing minor erosion during the Devonian. The transition to the second major phase in the Phanerozaic structural development, during which the Sorgenfrei-Tornquist zone came into existence, is recorded by regional deposition of Carboniferous sediments. These sediments are, however, mostly removed by tater erosion. A syn-rift phase characterized by sedimentation in graben areas and expanding basins commencing in the Rotliegendes and continuing through the Triassic, Jurassic and Lower Cretaceous. This phase was probably initiated by a Late Carboniferous- Early Permian tensional dominated right-lateral wrench fault system within the Sorgenfrei-Tornquist zone. A Post-rift development phase dominated by Late Cretaceous carbonate sedimentation. During Late Cretaceous and Early Tertiary times the Bornholm area was strongly affected by inversion tectonism caused by compressional strike-slip movements. This resulted in reverse faulting and uplift and erosion of former basinal areas. Understanding the two latter phases is important for understanding the present distribution of the Palaeozoic. A key to understanding the hydrocarbon potential of the area is the maturation of the organic matter in the main potential source, the Ordovician Upper Alum Shale. Maturity was mainly achieved during the Silurian to Late Palaeozoic time, and little further maturation took place later. The Upper Alum Shale is accordingly expected to be overmature in the main part of the study area and mature in the Hano Bay Basin. This reflects the assumed primary uniform thickness of the Lower Palaeozoic, with a general thinning towards the northeast. A Caledonian to Variscian phase encompassing the Lower Palaeozoic sediments. The sediments are assumed originally to have showed a gradual thickness increase towards the Caledonian Deformation Front located to the south. This pre-rift development may be further subdivided into three sub-phases: A period of slow sedimentation on a relatively stable platform as recorded by the uniformly low thicknesses of the Cambrian to Lower Silurian sediments. A period of foreland-type rapid sedimentation commencing in the Llandoverian to Wenlockian, continuing in the Ludlovian and possibly into the Devonian. The period is characterized by /olding and uplift of the Caledonides to the south causing tectonic loading of the foreland and resultant rapid sedimentation in the foreland basin. A period of gravitational collapse causing minor erosion during the Devonian. The transition to the second major phase in the Phanerozaic structural development, during which the Sorgenfrei - Tornquist zane came into existence, is recorded by regional deposition of Carboniferous sediments. These sediments are, however, mostly removed by tater erosion. A syn-rift phase characterized by sedimentation in graben areas and expanding basins commencing in the Rotliegendes and continuing through the Triassic, Jurassic and Lower Cretaceous. This phase was probably initiated by a Late Carboniferous- Early Permian tensional dominated right-lateral wrench fault system within the Sorgenfrei-Tornquist zone. A Post-rift development phase dominated by Late Cretaceous carbonate sedimentation. During Late Cretaceous and Early Tertiary times the Bornholm area was strongly affected by inversion tectonism caused by compressional strike-slip movements. This resulted in reverse faulting and uplift and erosion of former basinal areas. Understanding the two latter phases is important for understanding the present distribution of the Palaeozoic. A key to understanding the hydrocarbon potential of thearea is the maturation of the organic matter in the main potential source, the Ordovician Upper Alum Shale. Maturity was mainly achieved during the Silurian to Late Palaeozoic time, and little further maturation took place later. The Upper Alum Shale is accordingly expected to be overmature in the main part of the study area and mature in the Hano Bay Basin. This reflects the assumed primary uniform thickness of the Lower Palaeozoic, with a general thinning towards the northeast.

From shale oil to biogenic shale gas: retracing organic-inorganic interactions in the Alum Shale (Furongian-Lower Ordovician) in southern Sweden

AAPG Bulletin ◽  
2015 ◽  
Vol 99 (05) ◽  
pp. 927-956 ◽  
Author(s):  
Hans-Martin Schulz ◽  
Steffen Biermann ◽  
Wolfgang van Berk ◽  
Martin Krüger ◽  
Nontje Straaten ◽  
...  
Keyword(s):  
Shale Gas ◽  
Shale Oil ◽  
Southern Sweden ◽  
Alum Shale ◽  
Lower Ordovician

Hydrocarbons from non-marine source rocks

1988 ◽  
pp. 221-244
Author(s):  
MALVIN BJORØY ◽  
PETER BARRY HALL ◽  
RITA LØBERG ◽  
JOSEPHINE ANN MCDERMOTT ◽  
NIGEL MILLS
Keyword(s):  
Source Rocks ◽  
Marine Source

Stable carbon and oxygen isotope geochemistry of the upper Visingsö Group (early Neoproterozoic), southern Sweden

1999 ◽  
Vol 136 (1) ◽  
pp. 63-73 ◽  
Author(s):  
JOAKIM SAMUELSSON ◽  
HARALD STRAUSS
Keyword(s):  
Organic Carbon ◽  
Oxygen Isotope ◽  
Isotope Geochemistry ◽  
Geochemical Data ◽  
Stable Carbon ◽  
Southern Sweden ◽  
South Central ◽  
Carbon And Oxygen Isotope ◽  
The Village ◽  
Early Neoproterozoic

A newly measured and sampled section in the upper part of the early Neoproterozoic Visingsö Group, south central Sweden, has been investigated for its stable carbon and oxygen isotope geochemistry. The 30 m-thick succession crops out on the southeastern shore of Lake Vättern, close to the village of Boeryd, and consists mainly of black mudstones with carbonate lenses, some of which have been dolomitized. High H/C ratios of the kerogen preserved in the investigated succession indicate that organic carbon generally is well preserved. The observed δ13Corg values are comparable to previously observed Neoproterozoic organic carbon values, with the exception of a few exceptionally 13C-depleted kerogens, with δ13Corg[ges ]−41.1 ‰. The latter are interpreted to be the result of fermentative bacterial reworking of sedimentary organic matter. The Boeryd carbonates display an unusual array of heavy δ18O values (with δ18O[les ]+3.3 ‰) that are interpreted as reflecting deposition in an arid climate. Geochemical data indicate that the carbonates have been diagenetically altered, but only to a limited extent, and a range of δ13Ccarb values from +2.4 to +4.7 ‰ appears to be representative of the primary seawater composition for the time of deposition of the upper Visingsö unit. Positive carbonate isotope values are typical for lower Neoproterozoic, pre-Varangerian successions elsewhere. The C isotope values obtained from the Boeryd section, although not conclusive by themselves, are consistent with the formerly biostratigraphically and radiometrically inferred early Neoproterozoic age for the upper Visingsö Group.

GEOLOGY AND HYDROCARBON POTENTIAL OF THE SOUTHERN GEORGINA BASIN, AUSTRALIA

2001 ◽  
Vol 41 (1) ◽  
pp. 139 ◽  
Author(s):  
G.J. Ambrose ◽  
P.D. Kruse ◽  
P.E. Putnam
Keyword(s):  
Early Carboniferous ◽  
Source Rocks ◽  
Peak Oil ◽  
Middle Cambrian ◽  
Late Cambrian ◽  
Oil Generation ◽  
World Class ◽  
Lower Palaeozoic ◽  
Southwestern Margin ◽  
Intracratonic Basin

The Georgina Basin is an intracratonic basin on the central-northern Australian craton. Its southern portion includes a highly prospective Middle Cambrian petroleum system which remains largely unexplored. A plethora of stratigraphic names plagued previous exploration but the lithostratigraphy has now been rationalised using previously unpublished electric-log correlations and seismic and core data.Neoproterozoic and Lower Palaeozoic sedimentary rocks of the southern portion of the basin cover an area of 100,000 km2 and thicken into two main depocentres, the Toko and Dulcie Synclines. In and between these depocentres, a Middle Cambrian carbonate succession comprising Thorntonia Limestone and Arthur Creek Formation provides a prospective reservoir-source/seal couplet extending over 80,000 km2. The lower Arthur Creek Formation includes world class microbial source rocks recording total organic carbon (TOC) values of up to 16% and hydrocarbon yields up to 50 kg/tonne. This blanket source/seal unconformably overlies sheetlike, platform dolostone of the Thorntonia Limestone which provides the prime target reservoir. Intra- Arthur Creek high-permeability grainstone shoals are important secondary targets.In the Toko Syncline, Middle Cambrian source rocks entered the oil window during the Ordovician, corresponding to major sediment loading at this time. The gas window was reached prior to structuring associated with the Middle Devonian-Early Carboniferous Alice Springs Orogeny, and source rocks today lie in the dry gas window. In contrast, high-temperature basement granites have resulted in overmaturity of the Arthur Creek Formation in the Dulcie Syncline area. On platform areas adjacent to both these depocentres source rocks reached peak oil generation shortly after the Alice Springs Orogeny; numerous structural leads have been identified in these areas. In addition, an important stratigraphic play occurs in the Late Cambrian Arrinthrunga Formation (Hagen Member) on the southwestern margin of the basin. Key elements of the play are the pinchout of porous oil-stained, vuggy dolostone onto basement where top seal is provided by massive anhydrite while underlying Arthur Creek Formation shale provides a potential source.

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