Speaker
Description
Mineral precipitation reshapes pore geometry, connectivity, and interfacial structure, with direct consequences for diffusive and advective transport in variably saturated porous media. While it is well established that classical laws such as Kozeny-Carman and Archie’s law break down in fully saturated reactive systems, analogous saturation-based closures-such as Millington-Quirk-type relationships for effective diffusivity and relative-permeability formulations for flow-are still widely applied under partial saturation. This practice implicitly assumes transport is controlled by saturation and porosity, even as mineral precipitation actively modifies pore-scale pathways. Our work challenges this assumption by showing that precipitation-driven microstructural evolution alters transport independently of water saturation.
Two experimental systems are developed. In a first set of column-scale experiments targeting diffusive transport, partially saturated porous media are monitored using time-resolved X-ray micro-computed tomography. Three-dimensional imaging resolves the spatial evolution of mineral precipitation, revealing preferential nucleation at gas-water interfaces and a strong, systematic increase in precipitate volume with increasing gas content. Pore-scale simulations performed on reconstructed micro-CT images are used to quantify the resulting evolution of effective diffusivity within the chemically evolving pore space. A second, dedicated experimental setup is designed to investigate advective transport. This system combines X-ray CT imaging with differential pressure measurements to directly quantify permeability changes induced by mineral precipitation under partial saturation conditions. By linking evolving pore-scale mineralization patterns to macroscopic flow responses, these experiments isolate the effect of precipitation on permeability independently of saturation changes.
By integrating diffusion and advection-focused experiments, this work provides rare, benchmark-quality datasets and a mechanistic basis for extending saturation-based transport closures to chemically evolving, partially saturated porous media. The resulting constitutive insights are suitable for implementation in sensitivity analyses and upscaling efforts, with implications for systems ranging from monument degradation and agricultural soils to subsurface energy technologies and long-term nuclear waste containment, where partial saturation and interfacial mineralization may persist over centuries.
| Country | Germany |
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