Marthe Grønlie Guren (Njord, UiO): "Linking dissolution rates at carbonate surfaces using X-ray tomography and numerical modelling".
Abstract: Investigations of mineral surface reactivity have recently challenged the classical approach of determining dissolution rates from mineral powders as crystals or more generally mineral-fluid interfaces often exhibit heterogeneous and/or anisotropic reactivity. Here, we provide a detailed characterization of the dissolution kinetics of carbonate materials in 3D using X-ray microtomography with a resolution below 1 µm. The local dissolution rates determined at crystal faces, edges and corners from calcite dissolution experiments are then used to constrain a stochastic numerical model based on the probability of detachment. The model is first tested on a Kossel-like crystals and then extended to more complex dissolution cases in natural rocks.
Paiman Shafabakhsh (Njord, UiO) : "Neutron and X-ray imaging of reactive-mixing in porous rocks"
Abstract: Understanding flow and mixing processes in porous media is important in many natural and industrial systems. Porosity evolution during mineral precipitation in rocks can control the fluid mixing properties and the reactivity of fluids within rocks. Here, we use time-lapse 3D neutron and X-ray micro-tomography imaging to explore fluid mixing into Berea sandstone core samples during in-situ carbonate precipitation. Neutron imaging allows tracking of the flow inside the rock and X-ray imaging illuminates the regions where mineral precipitation occurred. We investigate the flow of heavy water under the influence of the calcite precipitation which is induced by the reactive mixing between CaCl2 and Na2CO3. By solving the advection equation using the contrast in neutron attenuation from time-lapse images, we derive the 3D velocity field of the injected fluids. Our results show the sensitivity of flow velocity distribution to the evolving porosity, with a wider range of velocity magnitude of flow in the presence of mineral precipitation.
Dag Kristian Dysthe (Njord, UiO): An update on his work at the moment.
You will find the schedule for Njord Seminar Series Fall 2022 here.
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