3d Digital Outcrop Models: Impact of Data Spacing and Location from Modelling Geometries of Epeiric Carbonate Sand Bodies — A Middle East Analog

Denis Palermo¹, Sergio Nardon¹, Thomas Aigner², and Wolfgang Blendinger^3
1Sedimentology, Petrography & Stratigraphy Dept., Eni Exploration & Production, San Donato Milanese, Italy
²Institute of Geosciences, University of Tuebingen, Tuebingen, Germany
³Department of Petroleum Geology, Technical University of Clausthal, Clausthal, Germany

Triassic Upper Muschelkalk carbonates in the South-German Basin were studied as an outcrop analog to the Permo-Mesozoic “layer-cake” reservoir systems in the Middle East as part of the GECO-project, a joint Eni E&P - University research collaborations on the “Geometry of Carbonate Objects”. Similar to these reservoirs, Muschelkalk carbonates were deposited in an epicontinental, very gently inclined carbonate ramp. The reservoir facies consist of skeletal and oolitic carbonate grainstones, and are organised in a pronounced hierarchy of stratigraphic cycles. Based on outcrops, cores, GR logs and thin sections, the integrated study is focussed on geological 3D-modelling with the software Petrel.

Deterministic interactive facies modelling of 56 stratigraphic sections (“virtual wells”) demonstrate that apparent layer-cake stratigraphy at regional scale shows subtle clinoform geometries at reservoir scale. The resulting high resolution model was used to develop a workflow for the deterministic numerical reproduction of the main geometric features by using the full dataset.
In order to evaluate exploration scenarios several other facies models were reproduced for the same area, using varying quantities of datapoints from different stratigraphic sections. Decimated distributions were conceived with a random location of the wells, or regularly distributed in the study area, distributed along sedimentary trends or along the major dip direction of the platform. Moreover, a few closely spaced wells have been used to simulate a field appraisal.

The scenarios show significant differences in terms of size and shape of the facies bodies, which results in strongly varying volumetrics compared to the “full dataset” model.

Many thanks are due to Eni Exploration and Production management for having promoted and supported the project and given the permission to present these outcomes.

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