Influence of small-scale heterogeneity on upward CO2Â plume migration in storage aquifers

To analyze the cause of such overestimation, we introduce a dimensionless heterogeneity factor to characterize different levels of heterogeneity. The influence on CO2 migration is quantified with respect to a variety of heterogeneity factors, correlation lengths, and fluid viscosity ratios for isotropic and anisotropic media. Our findings suggest that small-scale heterogeneities should not be ignored in core analysis, even for cores that appear relatively homogeneous and do not have distinguishable heterogeneous patterns. In addition, relative-permeability curves measured from core-flood experiments under high-flow-velocity conditions (a common practice to eliminate capillary end-effects) should not be directly used in modeling low-velocity CO2 migration if small-scale heterogeneities are present.