Figure 1

Sketch of possible reaction settings during CO ₂ storage in basalt. System 1 (S1) is close to the injector and contains a wet CO₂ (0.5 mole% H₂O at 100 bar and 40 C) with no residual water; system 2 (S2) is fully in the H₂O rich phase with CO₂ diffusing in from the plume boundary; and system 3 (S3) is at the boundary of the CO₂ plume with both sufficient non-wetting CO₂ at a constant CO₂ partial pressure of 100 bar and with sufficient water wetting the mineral surfaces and available for reactions.