ABSTRACT: Permeability Estimation from the Parameters of a Particle-Size Distribution
PANDA, MANMATH N., and LARRY W. LAKE, University of Texas at Austin, Austin, TX
Single-phase permeability of a permeable medium is an important physical property. Any study of transport through a permeable medium requires a precise knowledge of this property. While its use has always been extensive, direct measurement of permeability is difficult, expensive, and, in some cases, imprecise. Hence, our alternative to direct measurement is to infer it from grain-size distribution parameters as from an unconsolidated core. Such a method would also allow us to detect the origin behind facies-determined differences in the permeability from outcrop measurements, the original motivation for this work.
We discuss a modified Kozeny model to estimate the single-phase permeability of unconsolidated sands using the parameters of its grain-size distribution. Particle-size distribution data, such as the coefficient of variation and the skewness of the distribution along with other physical properties such as the porosity and tortuosity, are used to calculate the permeability of the sand. The permeabilities so generated are then compared with the experimental data of Beard and Weyl, and Krumbein for model verification. We performed a Monte Carlo simulation to study the sensitivity of various parameters on the performance of the model.
Our results show that the coefficient of variation of the grain-size distribution and the mean grain size, respectively, have the largest influence on permeability variations at a typical range of porosity of 10-30%. The skewness of the grain-size distribution has very little influence. This model can also be used to predict the permeability of consolidated rocks by incorporating a cementation coefficient that can be predicted from thin section study of the medium.
AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)