New type of pore-snap-off and displacement correlations in imbibition

Kamaljit Singh, Tom Bultreys, Ali Q. Raeini, Mosayeb Shams, Martin J. Blunt

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)
18 Downloads (Pure)


Imbibition of a fluid into a porous material involves the invasion of a wetting fluid in the pore space through piston-like displacement, film and corner flow, snap-off and pore bypassing. These processes have been studied extensively in two-dimensional (2D) porous systems; however, their relevance to three-dimensional (3D) natural porous media is poorly understood. Here, we investigate these pore-scale processes in a natural rock sample using time-resolved 3D (i.e., four-dimensional or 4D) X-ray imaging.

We performed a capillary-controlled drainage-imbibition experiment on an initially brine-saturated carbonate rock sample. The sample was imaged continuously during imbibition using 4D X-ray imaging to visualize and analyze fluid displacement and snap-off processes at the pore-scale.

We discover a new type of snap-off that occurs in pores, resulting in the entrapment of a small portion of the non-wetting phase in pore corners. This contrasts with previously-observed snap-off in throats which traps the non-wetting phase in pore centers. We relate the new type of pore-snap-off to the pinning of fluid-fluid interfaces at rough surfaces, creating contact angles close to 90°. Subsequently, we provide correlations for displacement events as a function of pore-throat geometry. Our findings indicate that having a small throat does not necessarily favor snap-off: the key criterion is the throat radius in relation to the pore radius involved in a displacement event, captured by the aspect ratio.
Original languageEnglish
Pages (from-to)384-392
Number of pages9
JournalJournal of Colloid and Interface Science
Early online date27 Nov 2021
Publication statusPublished - Mar 2022


  • 4D X-ray imaging
  • Imbibition
  • multiphase flow
  • pore-filling
  • porous media
  • snap-off

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry


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