Role of Impurities on CO2 Injection: Experimental and Numerical Simulations of Thermodynamic Properties of Water-Salt-Gas Mixtures (CO2 + Co-Injected Gases) under Geological Storage Conditions

Abstract : Regarding the hydrocarbon source and CO2 capture processes, fuel gas from boilers may be accompanied by so-called "annex gases" which could be co-injected in a geological storage. These gases, such as SOx, NOx, or oxygen for instance, are likely to interact with reservoir fluids and rocks and well materials (casing and cement) and could potentially affect the safety of the storage. However, there are currently only few data on the behaviour of such gas mixtures, as well as on their chemical reactivity, especially in the presence of water. One reason for this lack comes from the difficulty in handling because of their dangerousness and their chemical reactivity. Therefore, the purpose of the "Gaz Annexes" project was to develop new experimental and analytical protocols in order to acquire new thermodynamic data on these annex gases, in fine for predicting the behaviour of a geological storage of CO2 + co-injected gases in the short, medium and long terms. This paper presents the main results from the "Gaz Annexes" project concerning acquisition of PVT experimental and pseudo-experimental data to adjust and validate thermodynamic models for water / gas / salts mixtures as well as the possible influence of SO2 and NO on the geological storage of CO2. The "Gaz Annexes" project gives new insights for the establishment of recommendations concerning acceptable content of annex gases.