Abstract
In this paper, we consider a parallel finite volume algorithm for modeling complex processes in porous media that include multiphase flow and geochemical interactions. Coupled flow and reactive transport phenomena often occur in a wide range of subsurface systems such as hydrocarbon reservoir production, groundwater management, carbon dioxide sequestration, nuclear waste repository or geothermal energy production. This work aims to develop and implement a parallel code coupling approach for non-isothermal multiphase multicomponent flow and reactive transport simulation in the framework of the parallel open-source platform DuMuX. Modeling such problems leads to a highly nonlinear coupled system of degenerate partial differential equations to algebraic or ordinary differential equations requiring special numerical treatment. We propose a sequential fully implicit scheme solving firstly a multiphase compositional flow problem and then a Direct Substitution Approach (DSA) is used to solve the reactive transport problem. Both subsystems are discretized by a fully implicit cell-centred finite volume scheme and then an efficient sequential coupling has been implemented in DuMuX. We focus on the stability and robustness of the coupling process and the numerical benefits of the DSA approach. Parallelization is carried out using the DUNE parallel library package based on MPI providing high parallel efficiency and allowing simulations with several tens of millions of degrees of freedom to be carried out, ideal for large-scale field applications involving multicomponent chemistry. As we deal with complex codes, we have tested and demonstrated the correctness of the implemented software by benchmarking, including the MoMaS reactive transport benchmark, and comparison to existing simulations in the literature. The accuracy and effectiveness of the approach is demonstrated through 2D and 3D numerical simulations. Parallel scalability is investigated for 3D simulations with different grid resolutions. Numerical results for long-term fate of injected CO2 for geological storage are presented. The numerical results have demonstrated that this approach yields physically realistic flow fields in highly heterogeneous media and showed that this approach performs significantly better than the Sequential Iterative Approach (SIA).
Highlights
Multiphase multicomponent flow with chemical reactions in porous media play a significant role for many applications in geological and reservoir engineering processes
In order to use a sequential approach to decouple twophase flow and reactive transport, we introduce two subsets I2u and Irt
We present the formulation of a geochemical model and the governing equations modeling two-phase multicomponent flow with reactive transport in porous media that will be used in the sequel
Summary
Multiphase multicomponent flow with chemical reactions in porous media play a significant role for many applications in geological and reservoir engineering processes. We can mention for instance the sequestration of CO2 in saline aquifers, the geological storage of nuclear waste or the prevention of groundwater pollution and the contaminant remediation. Numerical models have been increasingly used for this purpose, a trend that will continue because more sophisticated models and codes are being developed and computer costs keep decreasing. Significant efforts and Carbon Capture and Storage (CCS) is a promising way to mitigate the effects of global warming. Assessing the viability of geological storage must rely on numerical simulations due to the long time scales involved. Several physical and geochemical trapping mechanisms must be combined to ensure a high containment rate, and geochemical trapping becomes increasingly important over longer
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