Impact of sub-core scale heterogeneity on CO2/brine multiphase flow for geological carbon storage in the Minnelusa sandstone

CO₂ geological storage in deep saline aquifers is a mitigation option for CO₂ emissions due to its large storage capacity and immediate accessibility. Accurately determining the CO₂-brine relative permeability curves is key to the evaluation of CO₂ injectivity and sweep efficiency in reservoir simulation as well as the CO₂ injection in the field. This study highlights the remarkable effects of sub-core scale heterogeneity on the CO₂-brine multiphase flow properties of the Minnelusa Sandstone in Wyoming. Two unsteady state CO₂-brine drainage experiments were performed on the two samples. The first sample exhibits slanted laminated structure, while the second one represents a more homogeneous sandstone system. The CO₂ saturation distributions during drainage reveals that the main variation in multiphase flow properties of two core samples were attributed to the porosity distribution that leads to the capillary pressure heterogeneity. Assisted history matching was used to obtain the respective relative permeability curves, which suggests heterogeneity-dependent behavior. In addition, sensitive and uncertainty analyses indicate that physical and petro-physical properties of low-porosity and low-permeability bedding layers exert marked effects on CO₂ front breakthrough time and brine production. The results presented in this study help to gain insight into the CO₂-brine multiphase flow properties in heterogeneous sandstones and can pave the way for the upscaling of CO₂ migration and field-scale simulation accurately.