Investigation of mineral trapping processes based on coherent front propagation theory: A dawsonite-rich natural CO2 reservoir as an example

•Developed a set of concise mathematical models for coherent front propagation and mineral trapping in CCS.•Advanced the model from 1D to 2D coherent state and improved the conceptual understanding.•Established the reaction- or transport-limiting criteria for mineral trapping rate.•Explored the evolution of the coherent front of dawsonite and the impact of hydrodynamic dispersion on the front propagation. After nearly 30 years of research on geological carbon storage, studies providing an in-depth conceptual understanding of mineral trapping processes are still scarce. Based on the reaction front propagation theory, this paper developed a set of concise mathematical models for front propagation and mineral trapping in quasi-2D-advection-diffusion-dispersion-reaction-kinetics systems in the coherent state and explored the nature of long-term mineral trapping processes and the effects of hydrodynamic dispersion on the front propagation. A criterion based on dawsonite volume fraction and front propagation distance was established to determine whether the mineral trapping rate is reaction- or transport-controlled for the coherent reaction fronts. Combined with the numerical simulation, the mantle-magmatic-sourced CO2 invasion, and long-term CO2 storage was investigated for the Hailar natural CO2 reservoir. The conclusions include: (1) The relative errors of the concise models for coherent front propagation speed and mineral trapping rate are 3-10% and 0.5-10%, respectively. (2) For the complete reaction stage, mineral trapping rates are always transport-controlled and are proportional to Darcy velocity, the difference of total dissolved carbon concentrations, and the correction coefficient for the hydrodynamic dispersion; when reaction controlling, the mineral trapping rate is proportional to front propagation distance and upstream dawsonite precipitation rate. (3) Specific results related to propagation speed, front width, hydrodynamic dispersion and mineral trapping rate caused by changing the rate constants of minerals and albite volume fraction were also obtained.