High-energy, synchrotron-based x-ray difference micro-tomography was used to resolve the pore structure of a granular porous medium, as well as colloidal deposits within the pore space, with near-micron-scale resolution. This detailed structural information was used to define internal boundary conditions for three-dimensional lattice Boltzmann (LB) simulations of the effects of the colloidal deposits on pore fluid flow. Colloid accumulation was observed to be highly heterogeneous at the pore scale. As colloids accumulated in the pore space, the mean tortuosity increased and the tortuosity distribution became multi-modal, indicating the development of macro- scale heterogeneity. These changes in the geometry of the pore space also greatly reduced the bulk permeability of the porous medium. In addition, a time-series of measurements was used to observe the dynamics of the deposition process in a single sample with successive colloid loading. The pore structure evolved to become increasingly complex over time. LB simulations of solute transport indicated that these changes in pore structure produced anomalous diffusion behavior.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 1000 GEOCHEMISTRY;
- 1800 HYDROLOGY;
- 3200 MATHEMATICAL GEOPHYSICS (0500;
- 4400 NONLINEAR GEOPHYSICS (3200;