Toward probabilistic modeling of halite nucleation and growth during carbon storage process: pore scale modeling

摘要: To maximize safety and cost-efficiency of CO2 storage, it is necessary to understand how a high permeability in the near-well region is maintained. Nucleation and growth of salt crystals driven by the evaporation of formation water into under-saturated (dry) super-critical CO2 stream results in the changes in the porosity and permeability of the near well-bore area. Permeability reduction is the main reason of the injectivity loss in the context of CO2 storage in saline aquifers. According to recent studies, during CO2 storage, salt crystals form in two different forms: 1) single, large crystals in the aqueous phase, and 2) aggregates of micrometer size salt crystals in the gas phase. All the previous numerical studies at pore-scale addressed the formation of single, large crystals in the aqueous phase. In this work, we developed a 3D pore-scale reactive transport solver (a D3Q19 advection-diffusion Lattice-Boltzmann model) and took nucleation process into account via a new probabilistic approach to simulate the formation of micro-meter size salt crystals in the gas phase and their effect on changes in pore morphology and permeability for the first time. Comparing the results of porosity-permeability relation with some of the well-known clogging models, confirms the need for a new clogging model to capture the permeability reduction caused by salt aggregates.