Snap-off is an important dynamic multiphase flow phenomenon which occurs in porous media. It plays a dominant role in the residual trapping and mobilization/immobilization of nonwetting fluids such as hydrocarbons or CO₂. Current studies, applications, and threshold criteria of snap-off are mostly based on static or equilibrium conditions. Thus, the dynamics of snap-off which is relevant for many real world applications has rarely been systematically studied. While a static criterion indicates the snap-off potential for nonwetting fluids, the competition between the time required for snap-off and the local pore throat capillary number determines whether snap-off actually occurs. Using a theoretical model to couple the wetting film thickness to the local capillary number at the pore throat, we analyzed the dynamics of the wetting/nonwetting interface instability in sinusoidally constricted capillary tubes. The influence of dynamic factors as encapsulated by the effect of local capillary number on nonwetting fluid snap-off time were investigated for varying pore throat to pore body aspect ratio and pore body distances. The analysis showed that snap-off can be inhibited by a sufficiently large local capillary number even in cases where the static snap-off criterion has been met.


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 U.S. Departmentof Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC0001114.

Keywords and Phrases

Aspect ratio; Carbon dioxide; Film thickness; Interfaces (materials); Multiphase flow; Porous materials; Wetting; Capillary numbers; Dynamic factors; Equilibrium conditions; Interface Instability; Non-wetting fluids; OFF time; Pore scale; Theoretical modeling; Capillarity; Carbon dioxide; Hydrocarbon; Hydrological modeling; Immobilization; Mobilization; Multiphase flow; Porous medium; Local capillary number; Snap-off time

International Standard Serial Number (ISSN)

0043-1397; 1944-7973

Document Type

Article - Journal

Document Version

Final Version

File Type





© 2015 American Geophysical Union (AGU), All rights reserved.

Publication Date

01 Nov 2015