A Systematic, Multi-Scale Workflow for Carbonate Reservoir Characterisation: Example from Lower Cretaceous Carbonates of the Middle East

Bartenbach, Martin ¹; Wolpert, Philipp ¹; Aigner, Thomas ¹; Suess, M. Peter ²
(1)Department of Geosciences, Sedimentary Geology, University of Tuebingen, Tuebingen, Germany. (2) ETG/T, Wintershall GmbH, Kassel, Germany.

In contrast to established reservoir modelling for siliciclastic reservoirs, statistically oriented modelling workflows are often unsuitable for carbonate reservoirs, because of their complex heterogeneities on different scales, which are due to a combination of physical, biogenic and diagenetic processes.

A novel strictly hierarchical multi-scale reservoir modelling workflow was developed and tested with Lower Cretaceous Sulaiy carbonates of the Middle East. It involves the following steps:

1) Pore scale: analysis of pore networks by means of micro-CT-scans and thin sections supplemented by porosity and permeability measurements of core-derived mini-plugs. This generated a series of petrophysical rock types.

2) Facies scale: rock types group into rock type associations, which correspond roughly to lithofacies types. Permeability maps were generated for decimeter-scale core slabs of each lithofacies type by means of high-resolution minipermeametry. Decimeter-scale numerical micro-blocks were modelled for each lithofacies type.

3) Geobody scale: one or several facies types often form specific geobody types. The geometry, dimensions and lateral extent of major geobodies were measured in outcrop analogs to provide quantitative data on the dimensions of flow units.

4) Cycle and cycle set scale: geobodies and facies associations group in regular successions forming cycles and cycle sets. These were studied in outcrop analogues with the aim to distill trends in their vertical and lateral development. Cycle boundaries represent chronostratigraphic surfaces and provide the basis for layering schemes in 3-D geocellular models.

5) Regional scale: The hierarchy of cyclicity defines the overall sequence stratigraphic framework. General trends in reservoir architecture, distribution and quality were taken from the outcrop analogue and incorporated into the subsurface 3-D reservoir model.

One of the ultimate aims of this project are dynamic simulations that are based on the upscaling of the systematic multiple levels of reservoir heterogeneities.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.