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7th Middle East Geosciences Conference and Exhibition
Manama, Bahrain
March 27-29, 2006
Modeling
of a Khuff Reservoir Analog: Insights into
"Layer-Cake" Stratigraphy
1 Institute of Geosciences, University of Tuebingen, Sigwartstr. 10, Tuebingen, D -72074, Germany, phone:
+49 (0)7071-2975923, [email protected]
2 Sedimentology Petrography and Stratigraphy Dept. Carbonate Group, ENI E&P, via Emilia 1, San Donato Milanese, 20097, Italy
3 Department of Petroleum Geology, Technical University of Clausthal, Leibnizstr. 10,
Clausthal -Zellerfeld, D-38678, Germany
4 Institute of Geosciences, University of Tuebingen, Sigwartstr.10, Tuebingen, D -72074, Germany
In the framework of a joint ENI E&P – University research consortium, Triassic Muschelkalk carbonates in the South-
German Basin were studied as an analog to the “layer-cake” type Khuff reservoir system in the Middle East. Similar to the
Khuff, Muschelkalk carbonates were deposited in an epicontinental, very gently inclined carbonate ramp; reservoir facies
consist of skeletal and oolitic carbonate grainstones, and are organised in a pronounced hierarchy of cycles. A pilot study
focussed on a paleogeographically and stratigraphically selected portion of the Muschelkalk. Previous outcrop
sedimentology and correlation suggested simple layer-cake stratal patterns. However, high resolution 3-D modelling of
sedimentary body geometries and spatial distribution using Petrel imposed new correlation strategies between vertical
outcrop sections (pseudo-wells) and provided new insights: the apparent layer-cake stratigraphy turned out be a “pseudolayer-
cake”. While the boundaries of sedimentary cycles remain continuous over many tens of kilometres, the carbonate
grainstone reservoir bodies within the cycles show various stratal architectures. In particular, considerable differences
between the geometries of the sedimentary bodies during progradation and retrogradation could be demonstrated. This
“pseudo-layer-cake model” might be crucial in defining typical subseismic reservoir heterogeneities of epeiric carbonate
systems: continuous seismic
reflectors represent major cycles (time lines), while e.g. subtle offlapping geometries of
smaller-scale cycles are likely “hidden” between the reflectors, but fundamental for the assessment of the fluid flow
continuity inside the reservoir itself.