Effects of different mineral reaction kinetics equations on predicting long‐term CO ₂ mineral sequestration

CO2 geological storage (CGS) is one of the important means to effectively reduce greenhouse gas emissions. Mineral trapping is an important factor affecting long-term storage security. The process of mineral trapping is significantly affected by mineral reaction kinetics. Therefore, it is of great significance to clarify the influence trend and degree of the control equation of mineral reaction kinetics on predicting the process of CO2 storage and the amount of mineral sequestration. In this paper, the effect of different reaction rate equations on predicting long-term CO2 sequestration mechanisms are compared and analyzed by numerical simulation using the existing reaction rate equations. The results show that different reaction rate equations of related minerals have no significant effect on predicting the total amount of CO2 sequestration and the transformation relationship among different minerals, but will significantly affect different forms of CO2 sequestration, especially mineral trapping. The ratio of mineral trapping predicted by different reaction rate equations is 20% to 41%. And the predicted CO2 mineral trapping rate is twice as high when the linear rate equation is used as when the nonlinear rate equation is used. In previous studies, linear rate equations have been widely used to describe the dissolution/precipitation reactions of related minerals, which may greatly overestimate the reaction rate and theoretical capture capacity of minerals. Therefore, it is urgent to carry out reaction kinetics experiments and numerical simulation studies on various major minerals under the condition of CO2 geological storage in the future, to obtain a more accurate mineral dissolution/precipitation reaction rate equation and improve the ability to evaluate the long-term CO2 geological sequestration safety.