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EUR-09 Geology of the Southern Permian Basin area - Part 2
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Petroleum generation and migration in the Southern Permian Basin
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Thomas Pletsch, Bundesanstalt für Geowissenschaften und Rohstoffe (Germany)
Jörg Appel, Bundesanstalt für Geowissenschaften und Rohstoffe (Germany)
Dariusz Botor, AGH University of Science & Technology (Poland)
Chris Clayton, Geochemistry Consultant (United Kingdom)
Eckhard Faber, Bundesanstalt für Geowissenschaften und Rohstoffe (Germany)
Christoph Gaedicke, Bundesanstalt für Geowissenschaften und Rohstoffe (Germany)
Wojciech Gorecki, AGH University of Science & Technology (Poland)
Gion Kuper, TNO - Built Environment and Geosciences (Netherlands)
Jolanta Kus, Bundesanstalt für Geowissenschaften und Rohstoffe (Germany)
Rüdiger Lutz, Bundesanstalt für Geowissenschaften und Rohstoffe (Germany)
Anders Mathiesen, GEUS, Geological Survey of Denmark and Greenland (Denmark)
Christian Ostertag-Henning, Bundesanstalt für Geowissenschaften und Rohstoffe (Germany)
Bartosz Papiernik, AGH University of Science & Technology (Poland)
Frank van Bergen, TNO - Built Environment and Geosciences (Netherlands)
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The two major petroleum systems of the Southern Permian Basin (SPB) in Central Europe are sourced by the gas-prone Westphalian (upper Carboniferous) coal measures and the oil-prone Posidonia Shale (lower Jurassic). They account for the bulk of the exploited petroleum. Other petroleum systems are less productive and restricted to a few play regions, but they still provide a significant economic benefit. Sweet, low-asphaltene oils of lower Palaeozoic plays in the western Baltic Basin were generated from Cambrian, Ordovician, and potentially Silurian, source rocks with hydrogen-rich kerogen. Deep burial near the Törnquist-Teisseyre suture induced thermocatalytic gas generation along the SE Baltic coast.
Lower Carboniferous source rocks contributed to a number of fields whose dominant charge stems from the coal measures. In the southern North Sea and in the Polish Trough, however, lower Carboniferous source rocks with variable admixtures of marine kerogen play an important role on their own.
Their enormous thickness, wide distribution, and favourable burial history have made the Westphalian coal measures the most important source rocks of the SPB. Superposition of this huge hydrocarbon source by a variety of reservoir facies and top seals resulted in a great number of economically viable plays. Local enrichments in condensate, nitrogen, and sulphur were contributed from ancillary biogenic as well as from abiogenic sources.
The Zechstein petroleum system is sourced from algal kerogen that formed in hypersaline lagoons on the marginal platforms of an inland sea. Localised sapropelic shales and carbonates within the porous Main Dolomite generated mid-viscosity oils with appreciable sulphur contents. Producing plays are characterised by very short migration into stratigraphic traps within the same formation. The Posidonia petroleum system is sourced from oil-prone marine shales deposited in a restricted marginal sea at high sea level. In the western SPB, the Posidonia has reached the oil/gas window and is an excellent source rock. Eastward transition to terrestrial facies has deprived the lower Jurassic equivalents in the Polish Trough from becoming source rocks.
Localised lacustrine shales of the Wealden Formation have sourced light sweet oils in the Emsland and adjacent sub-basins. Their characteristic mixture of hydrogen-rich lacustrine and carbon-rich humic kerogen and the juxtaposition of sources and traps both relate to small-scale lateral changes within the depositional environment. Besides the widely explored petroleum systems, there is an unfathomed potential from shallow gas. Occurrences are common in the North Sea, but their volumetric extent has so far not been assessed systematically. Because shallow gas consists, to variable degrees, of thermogenic components generated from deeply buried source rocks, and of methane from biogenic processes acting at much shallower depth, compositional predictions are a major challenge in shallow gas exploration.
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