The Geochemical Impact of CO2 Injection in Limestone: From Experiments to Modeling
Limestone or calcite-rich carbonate formations are likely to be used as reservoirs for CO2 storage. Laboratory experiments show that aqueous solutions with dissolved CO2 can have a strong impact on the dissolution of calcite grains, particularly when the reaction is coupled to fluid movement. According to the conditions of the experiment (temperature, CO2 partial pressure, water-flow velocity), and to the rock fabric, a variety of dissolution patterns can develop, including worm-holing.
The presentation describes several experiments at the plug scale, achieved on several types of rocks. It discusses how the kinetic rates of calcite dissolution can be integrated in numerical simulations of these experiments. Several dissolution patterns were observed. The work focuses on the use of a-dimensional parameters to analyse the occurrence of these patterns.
In a last part, modelling tools and a-dimensional numbers are used to extrapolate the results obtained at the plug scale to the scale of the reservoir unit.