Compressible multicomponent two-‐phase flow in HYTEC: some applications to gas injection and impact of impurities
Résumé
HYTEC is a reactive transport code developed at MINES ParisTech since 1996. Over the last few years, a new two-‐phase flow module was embedded in HYTEC with emphasis on modularity and flexibility. Although based on the phase formulation of the flow problem, the method allows for the precise description of complex gases (multicomponent, non-‐ ideal), their thermodynamic and hydrodynamic behaviors, and the coupling with water-‐ rock interaction. The developed algorithm relies on several modules: the compressible multiphase flow problem (based on the fully implicit method), a complex thermodynamic operator (built on analytical modeling of equations of state, fluid property models and their derivatives), and a sequential iterative resolution of the reactive transport. The global coupling approach is organized around the sequential iterative call for two blocks: on the one hand two-‐phase flow, gaseous transport and thermodynamic operator, on the other hand chemistry and aqueous and gaseous transport. The impact of phase consumption (gas dissolution, exsolution of dissolved gases) on hydrodynamics is explicitly described. Several applications are proposed to illustrate the behavior of the code. E.g., the simulation of an impure CO2 injection in a homogeneous fully saturated reservoir (Figure 1) performed by Irina Sin during her PhD (Sin, 2015) displays some chromatographic effects due to differences in gas solubility. The gas current is formed by diffusion, advection-‐dominated flow, and by density-‐driven forces. In addition, the gas plume is enriched with less soluble gases (N2, O2 and H2O) at the two-‐phase front (Figure 2); oppositely, more soluble SO2 is depleted (Figure 3). Other applications can lay the basis for benchmarking exercises. Sin (2015) " Numerical simulation of compressible two-‐phase flow and reactive transport in porous media – Applications to the study of CO2 storage and natural gas reservoir " , Ph.D. MINES ParisTech. Figure 1 : 2D radial injection of CO2 with air impurity (4% N2 and 1% O2), liquid density after 10 y.