Effects of permeability heterogeneity on CO2 injectivity and storage efficiency coefficient

Abstract

AbstractWe study the dependency of CO2 storage efficiency coefficient (E) and injectivity index (Iinj) on the geostatistical parameters of the permeability field. CO2 injection simulations are conducted for multiple realizations of log‐normally distributed permeability fields parameterized by log permeability standard deviation (σ) and dimensionless horizontal correlation length (λ). Results show that the injectivity index increases with increasing λ, the magnitude of the effect depending on σ. Increasing σ leads to poorer injectivity for cases with small λ, but improves injectivity when λ is large. Further analysis indicates that the enhancing effect of σ on injectivity can be attributed to cases with channelized flow, while the decrease effect of σ is seen in more dispersive flow regime. The dependence of injectivity on both λ and σ is captured with a linear correlation between Iinj and a parameter group , where ξ is a dimensionless scaling parameter. The storage efficiency coefficient, on the other hand, decreases with both increasing σ and λ, and a simple linear fit is found between E and the parameter group λσ2, a well‐established heterogeneity parameter group describing e.g. macro‐dispersivity in solute transport studies. These relationships provide potentially useful tools for the preliminary evaluation of a site. Future studies should address the validity of the relationships in alternative injection scenarios and domain geometries. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd