Modeling CO2 Storage in Aquifers: Assessing the Key Contributors to Uncertainty

Abstract

Abstract We study the influence of different physical properties on the effectiveness of CO2 storage in aquifers. We present the results of a numerical sensitivity analysis using experimental design to quantify and compare the contribution of the most important parameters to the trapping of CO2. The work focuses on the impact of dissolution and residual trapping. Simulations using a reservoir model with properties and geometries representative of the Stuggart Formation in Ketzin (Germany) demonstrate how different trapping mechanisms are influenced by gravity segregation, fingering, and channeling. These studies show that horizontal permeability is the most influential parameter on the total amount of CO2 dissolved, as it facilitates the lateral migration of CO2, enhancing dissolution into the brine. Residual gas saturation Sgr is found to be the greatest contributor to the amount of residual CO2. As expected, higher Sgr will reduce CO2 mobility, producing a higher residual trail left by the CO2 plume as it migrates. In addition, permeability heterogeneity is a major contributor to both trapping mechanisms. After a suitable geological site for CO2 storage has been selected, our studies suggest that with appropriate well placement and injection strategy, at least 80% of the stored CO2 can be trapped within a few decades of the end of injection.