Speaker
Description
Dissolution–precipitation reactions in fractured rocks are central to subsurface energy applications such as CO₂ mineralization, geothermal operations, and long-term storage of reactive fluids. In diffusion-dominated, dead-end fractures, limited advective supply of reactants can promote localized mineral precipitation and clogging, degrading injectivity and long-term storage performance. To elucidate these pore-scale mechanisms and their implications for reservoir-scale design, we extend the previously developed two-dimensional LBM3RT reactive transport framework to a fully three-dimensional, multi-component advection–diffusion–reaction lattice Boltzmann model. The simulator couples transport of multiple aqueous species, homogeneous reactions, heterogeneous dissolution–precipitation, and dynamic solid-phase evolution within complex fracture geometries.
After verifying the 3D implementation against analytical diffusion–reaction solutions and published 2D crystal-growth morphologies, we apply the model to a dual-fracture system comprising a main flow conduit and a diffusion-dominated dead-end branch. We consider a simplified reaction network in which an in-situ mineral dissolves and a secondary mineral precipitates on fracture walls, mimicking carbonate-forming reactions relevant to engineered carbon mineralization. Systematic parameter studies are conducted to quantify net dissolution and precipitation rates, the spatial evolution of reaction fronts, and a pore-scale clogging index as functions of reaction kinetics, thermodynamic driving forces, inlet chemistry, hydrodynamics, and fracture geometry.
The simulations reveal several robust design principles. Lower dissolution rate constants enhance utilization of reactive mineral surfaces and reduce clogging risk by distributing reaction over a larger portion of the dead-end fracture. Lower precipitation rate constants similarly mitigate clogging. A smaller difference between the equilibrium constants of the dissolution and precipitation reactions leads to more balanced reaction fronts and less localization of precipitates. Increasing the inlet concentration of the mineral-forming aqueous species deepens penetration of the precipitation front while decreasing the peak clogging index, thereby improving mineralization efficiency. Larger dead-end apertures substantially increase total precipitation and front extent, suggesting that targeting reservoirs with fewer but wider diffusion-dominated branches is advantageous. Finally, introducing an impermeable passivation layer—representing slow-growing, low-permeability surface films—suppresses sustained local dissolution–precipitation but drives gradual migration of the reaction front toward the fracture tip, improving long-term access to reactive surfaces and reducing clogging.
Together, these results demonstrate that 3D LBM3RT is a powerful pore-scale tool for probing multiscale flow and reactive transport physics in fractured porous media and for guiding the design of subsurface energy operations. The insights obtained here provide mechanistic constraints on how geochemical conditions, flow regimes, and fracture architectures interact to control clogging in diffusion-dominated fractures, and they offer practical strategies—moderated reaction rates, optimized fluid composition, and favorable fracture geometries—for enhancing the efficiency and security of engineered carbon mineralization systems.
| Country | United States |
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