--> Abstract: Permian-Triassic Paleogeography and Stratigraphy of the West Netherlands Basin, by A. Speksnijder; #90990 (1993).

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SPEKSNIJDER, ARIE, Nederlandse Aardolie Maatschappij, Assen, Netherlands

ABSTRACT: Permian-Triassic Paleogeography and Stratigraphy of the West Netherlands Basin

During the Permian, the present West Netherlands basin (WNB) was situated at the southernmost margin of the southern

Permian basin (SPB). The thickness of Rotliegende sandstones therefore is very much reduced in the WNB. The relatively thin deposits of the Fringe Zechstein in the WNB, however, also contrast strongly in sedimentary facies with thick evaporite/carbonate alternations in the main SPB to the north, although the classic cyclicity of Zechstein deposition still can be recognized.

The Fringe Zechstein sediments are mainly siliciclastic and interfinger with both carbonates and anhydrites toward the evaporite basin. End members are thin clay layers that constitute potential seals to underlying Rotliegende reservoirs, and relatively thick sandstones (over 100 m net sand) in the western part of the WNB. Nevertheless, favorable reservoir/seal configurations in the Fringe Zechstein seem to be sparse, because only minor hydrocarbon occurrences have been proven in the area to date.

The situation is dramatically different for the Triassic in the WNB. The "Bunter" gas play comprises thick Fringe Buntsandstein sandstones (up to over 250 m), vertically sealed by carbonates and anhydritic clays of the Muschelkalk and Keuper formations. The Bunter sandstones are largely of the same age as the classic Volpriehausen, Detfurth, and Hardegsen alluvial sand/shale alternations recognized elsewhere, but the upper onlapping transgressive sands and silts correlate with evaporitic clays of the Rot basin to the north.

A total volume of 65 x l09cu m of gas has so far been found in the Triassic Bunter sandstones of the WNB.

AAPG Search and Discovery Article #90990©1993 AAPG International Conference and Exhibition, The Hague, Netherlands, October 17-20, 1993.