Effects of solution supersaturation on barite precipitation in porous media and consequences on permeability: experiments and modelling
Poonoosamy, Jenna (Corresponding author)
Klinkenberg, Martina / Deissmann, Guido / Brandt, Felix / Bosbach, Dirk / Mäder, Urs / Kosakowski, Georg
Nukleare Entsorgung und Reaktorsicherheit; IEK-6
Geochimica et cosmochimica acta, 270 (2020) S. 43-60
New York, NY [u.a.] Elsevier 2020
10.1016/j.gca.2019.11.018
Journal Article
Nuclear Waste Management
Please use the identifier: http://dx.doi.org/10.1016/j.gca.2019.11.018 in citations.
The understanding of porosity evolution in porous media due to mineral reactions and its impact on the transport of fluids and solutes is important, as this is a key factor in the long-term behaviour of underground engineered systems. The implementation of such coupled processes into numerical codes requires a mechanistic understanding of the relevant precipitation/dissolution processes in porous media and model 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 consequential permeability changes. These experiments were modelled using the reactive transport code OpenGeoSys-GEM. Although the Kozeny-Carman equation is widely applied in numerical models describing porosity and permeability changes due to mineral dissolution and precipitation, it distinctively underestimated the permeability changes observed in the experiments. Instead, a porosity-permeability relationship involving a critical porosity at which the permeability decreases significantly had to be considered in the model. Post-mortem characterization (Scanning Electron Microscopy) highlighted the importance of including pore-scale information on passivation processes in order to get a better match between experimental and simulated results.