Aeolian grain flow architecture: hard data for reservoir models and implications for red bed sequence stratigraphy

This paper introduces the Cretaceous Etjo Formation of NW Namibia as a sedimentological analogue for the Leman Sandstone, the principal gas reservoir of the UK Southern North Sea. Special reference is made to the documentation of hard knowledge from the analogue for input into very fine-scale reservoir models suitable for upscaling. The data presented address the sedimentary aspects of reservoir heterogeneity in aeolian sandstones providing size populations for grain flow laminae which typically exhibit permeability of an order of magnitude better than the grain fall and wind-rippled strata which encase them. The results also have significant and more general implications for existing models of aeolian sequence stratigraphy. The data collected are used to demonstrate that there is no link between preserved bedform thickness and original dune height. This has implications for the role of subsidence in controlling preserved bedform thickness.