Abstract:
Objective Kaolinite is an important clay mineral in sedimentary rocks. The research purpose of this paper is to clarify the chemical behavior and change process of kaolinite in CO2 aqueous solution and explore the reaction law of CO2 with kaolinite.
Methods The reaction state of kaolinite with CO2 at different reaction stages under the station of 10 MPa and 60 ℃ was systematically evaluated by means of XRD, XRF, ICP and SEM. The changes of solid elements, crystal structure and ion concentration in reaction solution before and after kaolinite powder reaction were compared. Then combined with the structural characteristics of kaolinite, the change law of kaolinite in acid was clarified.
Results The results showed that the concentrations of Al3+ and Si4+ increased in the liquid phase, Mg2+ concentration increases first and then tends to be stable. The change of Si/Al (mass ratio) in solid powder is small, and the peak shape of diffraction curve is stable. There is no obvious dissolution of kaolinite aggregate, and there is slight dissolution at the edge of monomer.
Conclusions The change of kaolinite after reacting with CO2 is small and relatively stable in CO2 solution on the whole. The experimental results provide important parameters and basis for the impact of CO2 injection on reservoir characteristics and the feasibility study of gas/water alternative flooding.