Pore-scale modelling of CO2 storage in fractured coal

The disposal of CO2 is a key issue for greenhouse gas control. We apply a reactive transport model based on lattice Boltzmann and finite volume methods to simulate the injection of CO2-saturated brine into a fractured coal. Fluid flow, transport of solute and dissolution are modelled at the pore scale. Fracture closure under overburden pressure is considered in the numerical model by performing mineral detachment identification and aperture adjustment. Variations of permeability and porosity are investigated. Mechanical properties are calculated to study the effect of mineral dissolution on formation stability. The results show that injection of CO2 causes fracture demineralisation. However, the removal of minerals may result in closure of existing fractures increasing resistance to fluid flow. This paper helps improve understanding of CO2 injection into coal seams and discusses its potential effect on coal properties.