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Porosity and permeability in sediment mixtures
Patrick J Kamann1, Robert W Ritzi, David F Dominic
1Department of Earth and Environmental Sciences, Wright State University, Dayton, OH 45435, USA.
Ground Water
|June 30, 2007
Summary
This study presents an enhanced fractional-packing model for predicting porosity and permeability in mixed-grain sediments. The model accurately represents experimental data for poorly sorted sands and gravelly sands.
Area of Science:
- Sedimentology
- Geotechnical Engineering
- Pore Network Modeling
Background:
- Porosity and permeability in granular sediments are crucial for understanding fluid flow in subsurface environments.
- Predicting these properties in mixed-grain sediments is challenging due to complex grain interactions.
- Existing models often struggle to accurately represent fine grains within the pore spaces of coarser grains.
Purpose of the Study:
- To expand an existing fractional-packing model to better predict porosity in sediment mixtures with fine grains approaching the size of coarse-grain pores.
- To develop a permeability model for these mixed-grain sediments, integrating the enhanced porosity model and grain-size statistics.
- To validate the developed models against laboratory experimental data.
Main Methods:
- Expansion of a fractional-packing model to incorporate the influence of fine grains on the pore structure of coarser grains.
- Development of a permeability model utilizing grain-size statistics and the enhanced fractional-packing porosity model.
- Laboratory experiments involving systematic variation of grain sizes and volume fractions in poorly sorted sand and gravelly sand mixtures.
- Permeability measurements using both air- and water-based permeametry.
Main Results:
- The expanded fractional-packing model accurately predicts porosity in laboratory-created sediment mixtures.
- The developed permeability model, incorporating the enhanced porosity model, shows strong agreement with experimental permeability measurements.
- The models successfully represent the complex interplay between grain size distribution and pore characteristics in mixed sediments.
Conclusions:
- The enhanced fractional-packing model provides a robust framework for predicting porosity in mixed-grain sediments.
- The integrated permeability model offers reliable predictions for fluid flow in such systems.
- These findings improve the understanding and modeling of transport properties in heterogeneous granular materials.
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