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The Geological Modeling of Effective Permeabilities in Complex Heterolithic Lithofacies

NORRIS, R. J., and JONATHAN J. M. LEWIS, Imperial College, London, U.K.

Heterolithic is a term that can be used to describe the complex suite of ripple-scale sedimentary features ranging from flaser-bedded sandstone to sand-streaked mudstone. These facies can contain significant hydrocarbon saturations (e.g., the Kuparuk River Formation, Alaska), but because heterolithic facies form such complex units, the calculation of effective permeabilities and reservoir behavior is difficult. This paper presents a geologically based procedure for calculating effective permeabilities for such facies.

Heterolithic sediments can be classified into a limited number of lithofacies types in which flow is controlled by ripple scale sand unit bottlenecks. Clearly, it is important to quantify these features if larger scale flow characteristics are to be evaluated. This is achieved through the use of digitized photographic lithofacies maps and minipermeametry. Effective permeabilities at a number of scales are then calculated for each lithofacies type from the digitized maps using the renormalization procedure. These effective permeability datasets are then used to define the Representative Elementary Volume (REV) for each lithofacies type. REVs are scale-specific effective permeability values for each lithofacies type that fully honor the smaller scale geology. The spatial distribution of these REVs is then modeled from large scale photomosaics and the resultant data input into a black oil simulator for reservoir behavior studies.

 

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)