Sequence Stratigraphy Integrated with Petrophysical Rock Typing: A Case Study from Carbonate Reservoir Analogs (Muschelkalk, Triassic, German Basin)

Sascha Braun, RWE Dea AG, Wietze Laboratory, Industriestr. 2, 29323 Wietze, Germany, phone: 0049-5146-89283, fax: 0049-5146-89275, sascha.braun@rwedea.com and Thomas Aigner, Institute of Geosciences, University of Tuebingen, Sigwartstrasse 10, D-72074 Tuebingen, Germany.

Outcrop analog studies provide quantitative data on reservoir bodies as input for static reservoir modelling. This study reports on shelly versus oolitic carbonate shoal bodies. These were deposited on a carbonate ramp of the intracratonic Muschelkalk basin in Central Europe, which in several ways provides analogs to hydrocarbon reservoirs in the Middle East. In the Muschelkalk analogs, shoal reservoirs occur in the top parts of meter-scale shallowing-up cycles. These stack vertically to larger-scale transgressive and regressive trends, building multiple reservoir storeys. Within the larger-scale regression shoal bodies systematically increase in abundance, size and thickness. Individual reservoir bodies are up to 18 x 8 km in extend and up to 2 m thick. The shoal bodies during the larger-scale regression tend to be rich in oolites, while those during larger-scale transgression are dominated by molluscan shells. Lithofacies types do not show consistent poroperm patterns but scatter widely. However, focussing on pore types and using the petrophysical rock type approach leads to better defined fields in poroperm crossplots. The oolitic shoals are dominated by separate-vug pores providing little permeability (k < 5 mD). In contrast, the shelly shoals show primary interparticle porosity in addition to separate-vug, leading to better permeabilities (k(h) = 45-82 mD). Thus the best reservoir quality occurs during large-scale transgression due to the predominance of highly permeable shelly shoals. Regional high resolution sequence stratigraphy determined the reservoir distribution, i.e. the architecture and geometry of the shoal bodies. However, only integration with petrophysical rock typing provided information on reservoir quality.

Evolving Stratigraphic Techniques and Interpretation II
2005 AAPG International Conference and Exhibition (September 11-14, 2005) Technical Program