Reactive transport model of kinetically controlled celestite to barite replacement

Abstract. Barite formation is of concern for many utilisations the geological subsurface, ranging from oil and gas extraction to geothermal reservoirs. It also acts as a scavenger mineral retention radium within nuclear waste repositories. The impact its precipitation on flow properties has been shown vary by orders magnitude, emphasising need robust prediction models. An experimental flow-through column setup laboratory scale investigating replacement celestite (SrSO4) with barite (BaSO4) various input barium concentrations was taken basis modelling. We provide here comprehensive, geochemical modelling approach simulate experiments. Celestite dissolution kinetics, well subsequent nucleation crystal growth were identified most relevant reactive processes, which included explicitly in coupling. A digital rock representation granular sample used derive initial inner surface area. Medium (10 mM) high (100 concentration resulted comparably strong surge nuclei formation, followed continuous grain overgrowth finally passivation celestite. At lower (1 mM), significantly less, resulting fewer but larger crystals slow moving reaction front complete replacement. modelled mole fractions solid phase effluent chemistry match previous results. improvement compared models using empirical relationships that no a-priori knowledge prevailing supersaturations system needed. For subsurface applications utilising reservoirs or barriers, where plays role, developed model great benefit only solute are needed quantified alterations.