Pore scale study of multiphase multicomponent reactive transport during CO2 dissolution trapping

• Published in: Advances in water resources 2018-06, Vol.116, p.208-218
• Main Authors: Chen, Li, Wang, Mengyi, Kang, Qinjun, Tao, Wenquan
• Format: Article
• Language: English
• Subjects: CO2 sequestration; Earth Sciences; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Lattice Boltzmann method; Multiphase flow; Porous media; Reactive transport; Solubility trapping
• ISSN: 0309-1708; 1872-9657
• DOI: 10.1016/j.advwatres.2018.02.018

•Multiphase reactive transport during CO2 dissolution trapping is studied.•A pore-scale numerical model for above physicochemical processes is developed.•Pore-scale multiphase flow, mass transport and reactions are discussed in detail.•Evolutions of specific interfacial and efficient dissolution rate are analyzed.•Effects of wettability on the multiphase reactive transport processes are explored. Solubility trapping is crucial for permanent CO2 sequestration in deep saline aquifers. For the first time, a pore-scale numerical method is developed to investigate coupled scCO2-water two-phase flow, multicomponent (CO2(aq), H+, HCO3−, CO32− and OH−) mass transport, heterogeneous interfacial dissolution reaction, and homogeneous dissociation reactions. Pore-scale details of evolutions of multiphase distributions and concentration fields are presented and discussed. Time evolutions of several variables including averaged CO2(aq) concentration, scCO2 saturation, and pH value are analyzed. Specific interfacial length, an important variable which cannot be determined but is required by continuum models, is investigated in detail. Mass transport coefficient or efficient dissolution rate is also evaluated. The pore-scale results show strong non-equilibrium characteristics during solubility trapping due to non-uniform distributions of multiphase as well as slow mass transport process. Complicated coupling mechanisms between multiphase flow, mass transport and chemical reactions are also revealed. Finally, effects of wettability are also studied. The pore-scale studies provide deep understanding of non-linear non-equilibrium multiple physicochemical processes during CO2 solubility trapping processes, and also allow to quantitatively predict some important empirical relationships, such as saturation-interfacial surface area, for continuum models.