Simulation and experimental study of the reactive impurity effects in CO2 storage
Abstract
Carbon capture and storage (CCS) has emerged as a critical strategy for mitigating global CO₂ emissions. Although most research focuses on pure CO₂ storage, industrial flue gases often contain trace impurities such as SOₓ, NOₓ, and amines, which may fundamentally alter subsurface rock–fluid geochemical interactions. In this study, experimental investigations integrated with numerical simulations were conducted to investigate the geochemical processes between reactive impurities in CO₂ streams and rock–fluid systems. Various characterization techniques - including XRD, SEM, micro-CT, and liquid chromatography - were applied before and after batch experiments to track chemical component transport and changes in physical properties. Based on composition tracing, the chemical reactions occurring in three-phase systems were interpreted, and the relevant reaction parameters were used as controlling variables to fit objective functions (i.e. ion concentrations in the liquid phase) via numerical modeling. A reservoir simulation case study of a Danish depleted reservoir was carried out to evaluate the effects of the reactive impurity SO₂ in CO₂ streams on the near-wellbore rock–fluid system, using a reactive transport model developed in CMG-GEM. The influences of SO₂ concentration, injection rate, and impurity combinations were examined with respect to gas propagation, pH evolution, mineral dissolution and precipitation patterns, and porosity development in the near-wellbore region.