CO2 Mineralization in Basaltic Rocks
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Xia, Zhao
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Abstract
Carbon geological storage by mineralization presents a promising strategy for climate change mitigation due to its long-term stability and substantial storage potential. The injection of CO2-saturated water triggers sequential mineral dissolution and precipitation fronts that progressively alter rock porosity and permeability, and modify flow pathways in a self-homogenizing mineralization process. Eventually these coupled processes affect the injection performance, storage capacity and reservoir stability. This study explores the intricate interplay among mineralogy, pore structure, fluid chemistry, and the impacts of dissolution-precipitation on coupled fluid transport. First, we establish causal connections between basalt genesis and the ensuing pore structures, and investigate the impact of pore structure on connectivity, permeability and accessible pore-matrix surface area of basaltic rocks. We then identify the key minerals governing overall rock dissolution and quantify the reactivity and CO2 mineral trapping capacity of both basalt and basaltic sediments. Next, we study the fluid-rock interactions during diffusive and advective transport. Sequential tomographic images and complementary reactive-transport modeling allow us to elucidate the evolution of fracture-matrix interaction in the near and far-field of the injection well. Different injection strategies are assessed using a high-temperature and high-pressure reactive flow-through device to formulate optimized injection protocols tailored to diverse field conditions, aiming to enhance field-scale CO2 mineralization. Finally, we explore the local controls on mineral precipitation using Marangoni flow to mitigate near-wellbore salt accumulation during undersaturated CO2 injection. The findings of this study support the improved assessment of mineral trapping efficiency and reservoir storage capacity, and provide valuable insights for fluid selection during injection with implications for site identification for carbon geological storage.
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Date
2024-07-17
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Dissertation