A worldwide study of sandstone formations with large-scale cross-bedding reveals that the majority of these originated as transverse bed forms. It is possible to recognize the transverse origin as well as the geometric shapes of the depositional surfaces of some other bed forms. Investigations by K. Weber and others have aided in the understanding of the areal distribution of eolian transverse genetic units and thus allow for geologic modeling. Unfortunately, the genetic units may have cemented parts and thus may not produce as single reservoir units. By relating the petrophysical analysis of these sandstone sequences to a bedding evaluation, it is often possible to infer the nature and geometric distribution of the porous reservoir units and non-porous elements. Thorough geologic reservoir modeling may be derived from (1) a dipmeter survey and porosity logs, or (2) petrophysical core analysis and oriented bedding studies from full, continuous cores, or both. At least one is necessary.

With either data base it is possible to determine the presence and areal significance of permeability anisotropy controlled by the texture, fabric, and diagenesis of bedding lamina. The geometric determinations of dip angle and azimuth, combined with the genetic interpretation of areal extent of the reservoir unit, allow borehole formation evaluation to be geologically projected into the reservoir area between wells. Such a geologic modeling and analysis are important in completion practices, field development, water flooding, and reservoir analysis.

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