Impact of the Physical-chemical Interactions on the Sealing Capability of a Cap Rock for CO2 Containment in Aquifers

This study investigates the impact of dissolution and precipitation of the minerals that exist in a cap rock on CO2 containment in saline aquifers. A 2D model consisting of a storage reservoir and a cap rock disturbed with a fault is created using TOUGHREACT, a code for modeling reactive transport in porous media. Typical fluid and mineralogical compositions and petrophysical parameters are introduced. The storage mechanisms are evaluated and quantified based on the simulation results. The possible leakage amounts are determined based on variations of relevant parameters. A maximum of 0,1% of the injection rate is calculated. The effects of the dissolution and/or precipitation of the minerals on the storage capacity of the reservoir and on the sealing capability of the cap rock are estimated. The numerical results indicate significant porosity-permeability reductions in the fault in response to precipitation, which is expected to strengthen the cap rock integrity.