Mineral precipitation is one of the natural processes that significantly affects such actively developing technologies as CO2 sequestration, oil and gas extraction, hydraulic fracturing, and toxic heavy metals remediation. The most puzzling geochemical questions are related to the ability to predict the evolution of rock matrix properties such as porosity and permeability during exposure to reactive flow that results in mineral precipitation on the surface of pores. It has been a great challenge for scientific community to capture and distinguish the most important factors that govern mineral formation in porous materials and couple physical and chemical processes happening on length and time scales that can differ from each other by several orders of magnitude. Here, we will present results on combining X-ray tomography experiments with fluid dynamics simulations that allows us to uncover coupling between reactant transport and local mineral growth in porous matrix. In this study we used the supersaturated solutions containing barium (Ba2+) and sulfate (SO42-) ions that form a sparingly soluble salt – barite (BaSO4). We have been able to show that quantitative analysis of X-ray tomography images becomes possible, such as, the total amount of precipitated mineral, cluster analysis, etc. The results confirm a strong correlation between transport of the reactant and amount of precipitated mineral. Additionally, strontium (Sr2+) ions were used to model impurity presence in solution. We observed that the addition of impurity (strontium) decreased the growth rate and increased the nucleation rate during precipitation process, indicating that the impurity has opposite effects on the crystal nucleation and crystal growth processes.

Mineral precipitation in porous media: Quantification of X-ray tomography data and pore-scale reactive transport simulations

ACS Spring Meeting 2021

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