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Abstract: Predicting Reservoir Facies Distribution Using High Resolution Forward Stratigraphic Modeling (Upper Permian Zechstein 2 Carbonate, North Germany)

Karl Leyrer, Christian Strohmenger, Konrad Rockenbauch, Thilo Bechstadt

To improve the prediction of reservoir facies within the Upper Permian Zechstein 2 Carbonate (Ca2), high resolution forward stratigraphic modeling was performed. The results show differences in the sedimentary history of various parts of the Southern Permian basin, permitting a better prediction of reservoir facies distribution.

The Zechstein 2 Carbonate contains North Germany's largest hydrocarbon accumulation. The reservoir overlies the anhydrites of the first Zechstein cycle (Werra Anhydrite, or Al) and is sealed by the anhydrites of the second Zechstein cycle (Basal Anhydrite, or A2). The Ca2 can be subdivided into platform, upper slope, middle slope, lower slope, and basinal facies with a total of 26 subfacies types. It comprises the transgressive and highstand systems tracts of the third Zechstein sequence (ZS3) and the lowstand systems tract of the fourth Zechstein sequence (ZS4). Furthermore the Ca2 can be subdivided into seven parasequences indicating higher-order sea-level fluctuations.

Although the Ca2 in both Northwest and Northeast Germany share this geological framework. many differences concerning reservoir distribution exist between the two areas. A general stratigraphic simulation program (PHILTM 1.5) was used for two-dimensional modeling of the Ca2 throughout North Germany. Using well data along with published data and modifying the sedimentation- governing factors, it was possible to simulate the current sequence stratigraphic and facies model.

Sedimentation during Ca2-time can be characterized as a highly complex system; thus, only slight variations of the input data result in vastly different facies and stratigraphic patterns. This sensitivity offers the possibility to test depositional models and to estimate the relative influences of the sediment-controlling parameters during Ca2-time in different paleotopographic settings.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France