ESTIMATING PERMEABILITY IN SEDIMENT MIXTURES

Permeability in sediment mixtures of grain sizes varies non-linearly with the relative volume of the individual grain-size fractions. Koltermann and Gorelick (1995) and Kamann et al. (2007) showed that this relationship could be modeled with the Kozeny-Carman equation if an effective grain diameter is computed. If a mixture is dominated by coarse grains with some finer grains, the effective grain diameter should be computed using the geometric mean; if dominated by finer grains with some coarser grains, the harmonic mean should be used. When the mixture contains more than two sizes, this approach needs to be expanded in ways that are now being explored. To evaluate these ideas, permeability is being measured in a rigid-wall, constant head, permeameter for clastic sediment mixtures with grain-size distributions from those of naturally occurring deposits. Estimations of permeability computed from the Kozeny- Carman equation using different approaches to compute the effective grain diameter, are then being compared to measurements to evaluate these approaches.