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Production from Muschelkalk carbonates (Triassic, NE Netherlands): unique play or overlooked opportunity?

2005; Zoological Society of London; Volume: 6; Issue: 1 Linguagem: Inglês

10.1144/0060299

2047-9921

Michael Pöppelreiter, Ravi Borkhataria, Thomas Aigner, K. Pipping,

Paleontology and Stratigraphy of Fossils

The Triassic Muschelkalk carbonates are a unique play in NW Europe, producing hydrocarbons onshore The Netherlands. This paper aims at a comprehensive description of these relatively unknown reservoirs and speculates on additional play potential outside of the current production areas. The Muschelkalk Formation consists of partially porous Lower and Upper Muschelkalk carbonates separated by tight Middle Muschelkalk evaporites. The 100 m thick Lower Muschelkalk holds 1.9 BCM gas in the De Wijk Field. The reservoir is a limestone–dolomite–marl succession producing from several decimetres thick calcisilitic dolo-mudstones encased in tight lime-mudstones. The reservoir shows a stratified architecture composed of 16 cycles with thin but laterally continuous porous units. Good reservoir quality facies are concentrated in the upper third of these cycles. Porosities vary from 6 to 27%, (average 12%) and permeabilities range from 0.01 to 32 mD (average 0.06 mD). The reservoir rocks represent inner ramp sediments of a storm-dominated epeiric ramp. The 50 m thick Upper Muschelkalk contains 0.8 BCM gas in the Coevorden Muschelkalk Field. The reservoir consists of several decimetres thick peloidal-oolitic dolo-grain to packstones of good permeability interbedded with lower permeability dolo-mudstones to wackestones. Porosity varies from 5 to 29% (average 15%) and permeability ranges from 0.01 to 57 mD (average 1 mD). The permeable dolo-grainstones occur chiefly around peak transgression and early regression of the Upper Muschelkalk. The producing Upper Muschelkalk deposits represent the inner ramp section of a storm-dominated homoclinal ramp. Numerous gas shows in the Lower and Upper Muschelkalk, scattered over the onshore territory of The Netherlands, suggest possible missed pay and upside potential. The highest reservoir potential occurs in grainy dolomitic inner ramp deposits. These are likely to be located close to the existing fields in the NE Netherlands. Additionally, currently unrecognized potential could be present in southern Germany and eastern Poland.