Mechanism of Minerals Action in Reservoir During CCS

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Abstract The carbon capture and storage (CCS) is one of the most effective ways to control greenhouse gases emissions and mitigate greenhouse effects. There will be a series of effects on the physical properties and chemical composition of the reservoir after CO2 injection. It is of great significance to study the effect of CO2 injection on reservoir for better CO2 storage. In this paper, Through the mechanism model established by numerical simulation technology and the phase permeability hysteresis simulation method, the whole process of reservoir pH, mineral dissolution and precipitation and porosity change during CO2 storage was accurately described. The results indicate that CO2 firstly dissolves in water to form carbonic acid after injection into the reservoir, which will cause a drastic change acid-base properties of reservoir, manifesting as a significant decrease in pH value. Under the effect of H +, Partia mineral components(for example: anorthite) in the reservoir) are dissolved, however, some other minerals (for example: kaolinite and calcite) are precipitated, which significantly change the composition of underground aqueous solution. The reaction rate of CO2-water-rock is very slow. After stopping CO2 injection, the mineralization of all kinds of minerals still goes on for a long time. In addition, due to the effect of CO2-water-rock reaction, a certain increase of reservoir porosity is more conducive to CO2 migration in the reservoir.