Extended Roof Snap-Off for a Continuous Nonwetting Fluid and an Example Case for Supercritical CO₂


A dominant mechanism for residual trapping of a nonwetting fluid in porous media during imbibition is snap-off or the disconnection of a continuous stream of the nonwetting fluid when it passes through pore constrictions and when a criterion based on capillary pressure imbalance is met. While quasi-static criteria for Roof snap-off have been defined for pores based on the imbalance between capillary pressure across the front/tail meniscus and local capillary pressure at the pore throat, and expressed in terms of pore body to pore throat ratio for simplification, we extended the previous quasi-static snap-off criterion by considering the local capillary pressure imbalance between the pore body and the pore throat for both circular and noncircular pores when the wetting film exists. We then used the criterion to analyze results from computational fluid dynamics (CFD) simulations of multi-phase flow with supercritical CO₂ as the nonwetting fluid and water as the wetting fluid. The extended criterion successfully described most situations we modeled. Furthermore, we compared fluid interface shape for a noncircular 3D pore predicted by the minimum surface energy (MSE) theory against 3D CFD simulations. While the fluid interface shape at the pore throat for 3D simulation was consistent with the shape predicted by MSE theory, the shape could not be successfully predicted by the MSE theory at the upstream and downstream pore body. Moreover, film flow existed for the noncircular pore at the downstream pore body.


Civil, Architectural and Environmental Engineering


This material is based upon work supported as part of the Center for Frontiers of Subsurface Energy Security (CFSES) at the University of Texas at Austin, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001114.

Keywords and Phrases

Computational fluid dynamics simulations; Dominant mechanism; Fluid interface; Minimum surfaces; Non-wetting fluids; Pore scale; Snap-off; Supercritical CO; Capillarity; Capillary tubes; Carbon dioxide; Fluidity; Porous materials; Rivers; Roofs; Three dimensional; Computational fluid dynamics; Capillary pressure; Carbon dioxide; Computational fluid dynamics; Computer simulation; Imbibition; Porous medium; Supercritical flow; Three-dimensional modeling; CFD; Supercritical CO2

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Article - Journal

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© 2014 Elsevier, All rights reserved.

Publication Date

01 Feb 2014