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Goggin, D.J., M.A. Chandler, G. Kocurek, and L.W. Lake, 1988: Patterns of permeability in eolian deposits: Page sandstone (Jurassic), northeastern Arizona. SPE Formation Eval., 3, 297-306.
The eolian, Jurassic Page sandstone of northeastern Arizona is marked by a highly ordered heterogeniety. The heterogeneity is expressed by the intricate association of stratification types, which are a direct result of the depositional processes. The dominant stratification types in eolian reservoirs are grainflow, grainfall, and wind-ripple deposits, which form on the lee faces of migrating dunes; interdune deposits, which form between migrating dunes; and extra-erg deposits, which occur sporadically when other depositional environments encroach upon an eolian system. These stratification types each have a unique permeability range, which implies that the fluid migration routes in eolian reservoirs will be dictated by the geometry and types of strarification present.
One of the most important aspects of this study is the correlation of qualitative geologic descriptions with quantitative variables such as permeability. About 2000 measurements were made with a field minipermeameter on an outcrop of the Page sandstone. These data show that three distinct permeability modes directly relate to the different stratification types.
Permeability exhibits two components of variation: a structural or systematic component and a random or noise component. In this context, the structural component may be correlated to identifiable geologic processes, whereas the random component covers all unexplained variations. These definitions, however, are entirely scale dependent. That is, by decreasing the scale of measurement, structure is revealed in the random variation. This scale dependence is evident in the subject outcrop and, using several statistical tools, we are able to illustrate the "nested" nature of the spatial variation in permeability.
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