Mineral precipitation and dissolution in porous media and the associated change of transport parameters with respect to fluid movement and solute transport are of major interest in natural environments as well as in engineered systems, such as barriers in deep geological repositories for radioactive wastes. The implementation of such coupled processes into numerical codes used to evaluate porosity evolution and feedback on transport requires a mechanistic understanding of the relevant precipitation/dissolution processes and validation with quantitative experiments. In this context we conducted a series of flow through column experiments to investigate the effect of supersaturation on barite precipitation mechanisms (e.g. nucleation) and consequently on permeability changes. Although the Kozeny-Carman relationship is widely applied in models describing porosity and permeability changes due to mineral precipitation, it distinctively underestimated the permeability changes. Post mortem characterization (Scanning Electron Microscopy) highlighted the importance of including sub REV scale information such as crystal morphology (shape and surface roughness) and passivation processes in order to get a good match between experimental and simulated results. Currently we are developing experiments combining live imaging methods of the pore space (X-ray Computed Tomography, Magnetic resonance imagery and microfluidics) which enable precise quantification of parameters (e.g. reactive surface area, porosity) and their changes, facilitating the development of more precise relations to estimate the REV-scale reaction rates and transport properties.
About the Speaker: Jenna Poonoosamy, PhD
Dr. Poonoosamy is a Post-Doc at the Forschungszentrum Jülich. Her main field of study deals with water-rock interactions that govern the evolution of many natural and engineered subsurface systems. During her PhD, she worked on the benchmarking of reactive transport codes at the Paul Scherrer Institute in Switzerland. Her approach combining experiments, microscopic investigation and continuum scale modelling gave insights into the important parameters that need to be upscaled for realistic modelling. Recently, she participated in the development of Lattice Boltzmann model to investigate nucleation processes in porous media. Besides her experience in the field of reactive transport, she has also worked on the thermodynamic modeling of spent nuclear fuel and other relevant phases for the nuclear waste repository.
Host: Sergi Molins Rafa