NANOSCALE CONTROL OF GEOLOGIC CO2: A DOE ENERGY FRONTIER RESEARCH CENTER

The objective of the Center is to use new investigative tools, combined with experiments and computational methods, to build a next-generation understanding of molecular-to-pore-scale processes in fluid-rock systems, and to demonstrate the ability to control critical aspects of flow and transport in porous rock media, in particular as applied to geologic sequestration of CO₂. The objectives address fundamental science challenges related to far-from equilibrium systems, nanoscale processes at interfaces, and emergent phenomena. The specific overarching goals are to (1) establish, within 10 years, novel molecular, nanoscale, and pore-network scale approaches for controlling flow, dissolution, and precipitation in deep subsurface rock formations to achieve the efficient filling of pore space with injected supercritical CO₂, with maximum solubility and mineral trapping and near-zero leakage, and (2) develop a predictive capability for reactive transport of CO₂-rich fluid that is applicable for 100–1000 years into the future. The major technological gaps to controlling and ultimately sequestering subsurface CO₂ can be traced to far-from-equilibrum processes that originate at the molecular and nanoscale, but are expressed as complex emergent behavior at larger scales. Essential knowledge gaps involve the effects of nanoscale confinement on material properties, flow and chemical reactions, the effects of nanoparticles, mineral surface dynamics, and microbiota on mineral dissolution/precipitation and fluid flow, and the dynamics of fluid-fluid and fluid-mineral interfaces. The construction of quantitative macroscale process models based on nanoscale process descriptions is a critical additional fundamental knowledge gap. A combination of carefully integrated experiments and modeling approaches are used to evaluate essential molecular and nanoscale processes, and to treat the transition from the nanoscale to pore scale, and the effects that arise at that scale. Multiscale computational models and lab-scale experiments are used to understand the emergence of macroscale properties and processes. This presentation will highlight key results from three thrust efforts: mineral nucleation, fluids in nanpores and pore-scale fluid-solid interactions.