An Adaptive Multiphysics Model Coupling Vertical Equilibrium and Full Multidimensions for Multiphase Flow in Porous Media. Issue 7 (4th July 2018)

• Record Type: Journal Article
• Authors: Becker, Beatrix; Guo, Bo; Bandilla, Karl; Celia, Michael A.; Flemisch, Bernd; Helmig, Rainer
• Is Part Of: Water resources research. Volume 54:Issue 7(2018)
• Page Start: 4347
• Page End: 4360
• Publication Date: 2018-07-04
• Subjects: multiphysics -- porous media -- vertical integration -- multiphase flow -- gas injection -- model coupling; Hydrology -- Periodicals; 333.91
• DOI: 10.1029/2017WR022303
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: Efficient multiphysics (or hybrid) models that can adapt to the varying complexity of physical processes in space and time are desirable for modeling fluid migration in the subsurface. Vertical equilibrium (VE) models are simplified mathematical models that are computationally efficient but rely on the assumption of instant gravity segregation of the two phases, which may not be valid at all times or at all locations in the domain. Here we present a multiphysics model that couples a VE model to a full multidimensional model that has no reduction in dimensionality. We develop a criterion that determines subdomains where the VE assumption is valid during simulation. The VE model is then adaptively applied in those subdomains, reducing the number of computational cells due to the reduction in dimensionality, while the rest of the domain is solved by the full multidimensional model. We analyze how the threshold parameter of the criterion influences accuracy and computational cost of the new multiphysics model and give recommendations for the choice of optimal threshold parameters. Finally, we use a test case of gas injection to show that the adaptive multiphysics model is much more computationally efficient than using the full multidimensional model in the entire domain, while maintaining much of the accuracy. Key Points: A framework to couple a vertical equilibrium model to a full multidimensional model is developed A local criterion to determine the applicability of vertical equilibrium models is developed An efficient adaptive algorithm to assign subdomains is developed