Sedimentary Facies, Correlation, and Architecture of Rotliegend Reservoirs at the Southern Permian Basin Margin: The P01-Fa Case Study and the Challenged Myth of Layer-Cake Stratigraphy
Published:January 01, 2011
Andrea Moscariello, 2011. "Sedimentary Facies, Correlation, and Architecture of Rotliegend Reservoirs at the Southern Permian Basin Margin: The P01-Fa Case Study and the Challenged Myth of Layer-Cake Stratigraphy", The Permian Rotliegend of the Netherlands, Jürgen Grötsch, Reinhard Gaupp
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Sedimentology, log analysis, and high-resolution seismic data of the P01-FA structure, located in the western part of the Netherlands sector of the North Sea, were used to assess the correlatability and connectivity of the sand bodies, to unravel the complex internal reservoir architecture, and to demonstrate the impact that different conceptual geological models driven by different correlation methods can have on the correct understanding of the subsurface.
Heterogeneity of reservoir architecture and internal reservoir facies was first assessed based on a well-to-well log-based correlation, and the results were compared with a correlation based on detailed examination of an inverted seismic cube.
The overall resulting reservoir architecture based on detailed seismic-supported geological and stratigraphical analysis is significantly different from the one based only on well-to-well correlation, which may, at first glance, suggest a simple layer-cake architecture. The new model highlights how both, the internal structural and stratigraphical framework and the distribution of reservoir facies are most likely the result of a complex interplay of erosion, sedimentation, and tectonics. Tectonics was especially active during the lower and middle part of the Upper Rotliegend Group accumulation, thus influencing the lateral continuity of individual stratigraphic units.
This study also demonstrates how unravelling the internal composition of mixed aeolian–fluvial reservoirs, by detailed seismic examination, is critical to describe the reservoir heterogeneity in order to assess and predict connectivity. This is especially important in sandy reservoir containing minor reservoir elements which can create large permeability contrasts (e.g., baffles and barriers) and ultimately influence hydrocarbon flow.
This study demonstrates that an integrated evaluation using detailed sedimentary facies analysis and examination of seismic inversion data can allow a better understanding of reservoir geology by reducing the subsurface uncertainties and thus the risk associated with future appraisal and development activities.
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The Permian Rotliegend of the Netherlands
More than 50 years ago, the discovery of the giant Groningen Gas Field in the subsurface of the Netherlands by NAM B.V. marked a turning point inthe Dutch and European energy market initiating the replacement of coal by gas. Despite the fact that the Rotliegend dryland deposits in the Southern Permian Basin are one of Europe's most important georesources, no sedimentological overview is available to date for the subsurface of the Netherlands. This SEPM Special Publication presents for the first time such a summary of the present-day knowledge, including a comprehensive core atlas from on- and offshore wells.