micropore; dissolution precipitation; X-ray characterization; lattice Boltzmann; porous media; materials; permeability; diffusivity; nucleation theory
Prasianakis N.I., Haller R., Mahrous M., Poonoosamy J., Pfingsten W., Churakov S.V. (2020), Neural network based process coupling and parameter upscaling in reactive transport simulations, in Geochimica et Cosmochimica Acta
, 291, 126-143.
Molins S., Soulaine C., Prasianakis N.I., Abbasi A., Poncet P., Ladd A.J.C., Starchenko V., Roman S., Trebotich D., Tchelepi H.A., Steefel C.I. (2020), Simulation of mineral dissolution at the pore scale with evolving fluid-solid interfaces: review of approaches and benchmark problem set, in Computational Geosciences
Poonoosamy J., Westerwalbesloh C., Deissmann G., Mahrous M., Curti E., Churakov S.V., Klinkenberg M., Kohlheyer D., von Lieres E., Bosbach D., Prasianakis N.I. (2019), A microfluidic experiment and pore scale modelling diagnostics for assessing mineral precipitation and dissolution in confined spaces, in Chemical Geology
, 528, 119264.
Prasianakis N.I., Gatschet M., Abbasi A., Churakov S.V. (2018), Upscaling strategies of porosity-permeability correlations in reacting environments from pore-scale simulations, in Geofluids
, 2018(9260603), 1.
Precipitation and dissolution reactions in porous media dominate and control a large number of geochemical processes and industrial applications that span from geothermal energy and oil industry to pharmaceutical products, batteries, catalysts and to long-term nuclear waste containment. The precipitation-dissolution of minerals from aqueous solutions alters the pore space and its connectivity in a way that has a complex feedback to the ion transport in aqueous phase itself. Reactive transport models and simulations are providing the framework to understand and predict such phenomena. Very often, simulations are done at the macroscopic level (field scale) using a simplified description of the processes that actually take place at the microscale. For example, the change in permeability and diffusivity of a porous medium due to reactions is correlated to a global change of the bulk porosity in the medium, using empirical laws with adjustable parameters. There are clear evidences that the macroscopic properties of the medium depend on the physical and chemical processes that occur at the micropore scale in a strongly non-linear way. It is therefore not surprising, that smooth simplified relations, frequently are inadequate to predict accurately the temporal evolution of the system of interest. It is the microscopic physics per se that ultimately control the macroscopic processes. Fundamental in-depth understanding and accurate prediction of the underlying processes can be enhanced by direct pore-scale modeling, supported by experimental investigations.This project aims at:(i)combining a state-of-the-art reactive transport algorithm with classical nucleation theory concept;(ii)modelling competing precipitation mechanisms along with dissolution in realistic systems;(iii)using advanced synchrotron-based X-ray techniques to gain insight of the micro-meter level processes;(iv)validating the resulting numerical modelling framework against reactive transport experiments.The modelling activities will be based on the lattice Boltzmann (LB) numerical method and will be supported with results obtained from reactive transport experiments and advanced instrumental diagnostics with special focus to the celestite-barite system. The selection of the celestite-barite system is primarily motivated by the environmental relevance of barite scale formation in industrial applications related to large scale geochemical systems (oil exploration, geothermal heat extraction, uranium mining) and by the availability of an exceptionally complete set of thermodynamic and kinetic data. Moreover, results and samples of relevant reactive transport experiments have been already produced in-house, in the framework of a recently completed PhD thesis (2016). Therein, a simple system consisting of reactive celestite (SrSO4) intermixed with a comparatively inert matrix (quartz sand) was selected. By saturating the pore space with barium chloride solution (BaCl2), celestite is partially dissolved and replaced by the more insoluble barite (BaSO4) thus modifying the hydraulic properties of the medium (porosity, permeability, connectivity). Further characterization of experimental results will be carried out and analyzed at the Swiss Light Source (SLS) synchrotron, by means of advanced synchrotron-based X-ray techniques, including micro X-ray diffraction/fluorescence and 3D-microtomography. The prospected methodology will be able to describe, as a function of time and at high spatial resolution (micrometer scale), a number of observable processes and mechanisms, such as precipitation via homogeneous (nano-crystalline) and heterogeneous nucleation (epitaxial growth). The obtained results are expected to provide fundamental insights on the microscopic mechanisms governing dissolution-precipitation reactions and on how these mechanisms are affecting bulk hydraulic properties in geochemically relevant porous media.