Seminar Meysam Golmohammadi

Abstract

The capillary state of water in porous media plays a crucial role at the caprock-aquifer interface, preventing CO₂ leakage. Additionally, it significantly influences gas dissolution and solid mineralization reactions, which are vital for CO₂ trapping and other applications in earth science engineering. The effects of capillarity-based geochemistry have been documented and measured at the pore and microtube scales. However, these effects have not yet been explored at the upper core scale. This study aims to investigate how capillarity influences both the evaporation process and the carbonation reaction within an extensive pore network at the column scale. Experiments are conducted in decimeter-scale unsaturated columns containing brucite (Mg(OH)₂) grains and quartz sand. Injecting a CO₂ gas flow into the column results in the carbonation of brucite and the subsequent precipitation of hydrous Mg-carbonates within the pore space. In addition to in-situ analyses, including the measurement of CO₂ concentration and volumetric water content (VWC) at the top and bottom of the column during gas injection, several post-mortem analyses are conducted. These include Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and X-ray microtomography. The findings from these analyses indicate that capillary water influences crystal growth in small pores, the progression of carbonation reactions, and changes in pore structure due to brucite carbonation.