Reactive fluid flow in CO₂ storage reservoirs: A 2-D pore network model study

Water acidifies in the presence of CO₂ and prompts mineral dissolution. A 2-D pore network model scheme is developed to investigate reactive fluid flow in CO₂ storage reservoirs during injection when advective transport prevails. Mineral dissolution satisfies kinetic rate laws and continues until thermodynamic equilibrium is reached. In advection-dominant regimes, network simulation results show that species concentration, tube enlargement and flow rate can be summarized in terms of the dimensionless Damköhler number Da which is the ratio between advection time along a pore and the reaction time. Reservoirs will tend to experience localized enlargement near injection wells (before water drying) and compact dissolution in the far-field. The Damköhler number couples with initial pore-size variability to distort the relationship between mean tube diameter and either local or network-average flow rates. Both the Damköhler number and pore-size variability should be considered in field-scale numerical simulators.