Study of the role of spatial heterogeneities in the vicinity of a CO2 injection well.
Résumé
During CO2 injection, the near-well composite zones undergo geochemical, mechanical perturbations by gas stream. The numerical modelling of these coupled processes aims at complementing laboratory experiments to verify the integrity of CO2 storage.
This study presents the development of a two-phase flow module in the reactive transport software HYTEC. The former is resolved on a Voronoi-based finite volume discretization, using a water pressure/gas saturation formalism and a fully implicit method. The module was successfully compared against a self-similar solution and tested on the effects of gravity and absolute/relative permeability heterogeneity.
The coupling between the developed two-phase flow module and HYTEC’s reactive transport methods is sequential. The thermodynamic gas properties are calculated using the equations of state; the liquid and gas transports are resolved separately. The chemical equilibrium is made by software CHESS. One of the main problems is to feed volume (gas and water) changes from the chemistry-transport (and phase equilibrium) resolution back to the flow module. We present test case results of coupling code.