CO₂ Storage in Deep Aquifers: Towards an Evaluation of Mineral Trapping

Fortier, Brice¹, Magnier Caroline², Teddy Parra², Etienne Brosse² (1) IFP-School, Rueil Malmaison, France (2) Institut Français du Pétrole, Rueil-Malmaison, France

The disposal of CO2 in deep saline aquifers is a promising technological option to miti­gate the anthropogenic impact on climate. On the long term, in clastic sediments, it is expected that a part of the injected CO2 can be incorporated into minerals by dissolution of alumino-silicates and precipitation of carbonates. This mechanism is called mineral trap­ping. The study evaluates the influence of several parameters on the importance this process can induce in sandstones: mineral composition of the host rock and reservoir connectivity, associated petrophysical parameters, transport mechanism (diffusion vs. advective hydro­dynamism).

A reaction-transport numerical code, Diaphore, is used to calculate the evolution of stor­age as soon as injected CO2 is dissolved in formation water. The model integrates the whole geological system in which the disequilibrium induced by CO2 injection progressively van­ishes, as the system reaches a new equilibrium state. Typical sandstone compositions and transport scenarios are tested. The impact of several poorly constrained parameters on the simulation results, in particular part of the thermodynamical and kinetic data, or the feed­back of mineral reactions on petrophysical properties, is investigated. Optimal conditions to maximize CO2 mineral trapping are explored and discussed.