Evaluating changes to pore network structure of caprocks reacted with CO ₂ at high temperature and pressure

Modeling CO ₂ transport and CO ₂-induced porosity generation in caprock formations is important for evaluating CO ₂ storage safety and long-term containment in geological formations. One limitation of modeling complex coupled reaction and flow processes at the pore scale lies in the challenge of describing the evolution of complex 3D pore structures in this reactive environment. Samples of caprocks from current or potential CCS project sites were reacted with supercricital CO ₂ and brine at 160 C and 150 bars for ∼50 days to evaluate changes to the pore network in a reactive environment. Changes to the pore network were evaluated using small-angle neutron scattering and 3D high-resolution focused ion beam - scanning electron microscopy. Lithology appears to control the distribution and shape of pores in these mudstones. Results from this work will provide critical information about the nature of the pore network in caprocks for future modeling studies.