InterPore2025

Direct visualization of coupled mineral dissolution and precipitation to predict pore-clogging dynamics

20 May 2025, 14:35

15m

Oral Presentation (MS25) Advances in Carbon Mineralization: Unveiling Multiscale Geo-processes and Coupled Mechanisms MS25

Speaker

Jieun Kim (Hanyang University)

Description

Mineral dissolution and precipitation play a critical role in geofluid processes such as CO₂ mineralization, subsurface H₂ storage, and in-situ leaching. Despite their importance, the coupled dynamics of dissolution and precipitation underexplored, as most studies have examined them independently. In this study, we investigate the interplay between mineral dissolution and precipitation, focusing on their influence on pore-clogging dynamics. Using a microfluidic device with two embedded NaCl crystals and a straight channel, we directly visualize the simultaneous dissolution of NaCl and precipitation of AgCl as a mixture of AgNO₃ solution and ethanol flows through the channel. By adjusting the concentrations of ethanol and AgNO₃, we control the dissolution and precipitation rates, enabling systematic analysis of their effects. Through the pore-scale visualization, we reveal distinct dissolution and precipitation patterns under varying flow velocities and dissolution/precipitation rates, leading to different pore-clogging behaviors. Predictably, conditions with fast flow, rapid dissolution, and slow precipitation minimize clogging, while the opposite conditions exacerbate it. Interestingly, at intermediate conditions—where dissolution and precipitation rates are comparable—we observe dynamic transitions in pore-clogging over time. During the initial stage, at a given flow rate, mild clogging occurs in the channel between NaCl crystals, accompanied by subtle pressure fluctuations as accumulated precipitates are periodically flushed out. Over time, as the channel widens due to NaCl dissolution, precipitates accumulate near the NaCl crystals, leaving the center of the channel empty. However, as the channel widens further, the local flow velocity continues to decrease, allowing more precipitates to remain within the channel. Eventually, these precipitates tightly clog the outlet, leading to a rapid pressure increase. Through scaling analysis of dissolution and precipitation boundary layers in relation to flow rates and dissolution/precipitation rates, we identify the critical conditions for tight pore clogging. To the best of our knowledge, this study is the first to quantify and elucidate the coupled effects of mineral dissolution and precipitation on pore-clogging dynamics. Our findings offer critical insights into mineralization processes and pore-clogging prediction, with practical implications for subsurface resource management and geofluid engineering.