Pore-scale displacement mechanisms as a source of hysteresis for two-phase flow in porous media

S. Schlüter, S. Berg, M. Rücker, R. T. Armstrong, H. J. Vogel, R. Hilfer, D. Wildenschild

Research output: Contribution to journalArticleAcademicpeer-review

91 Citations (Scopus)

Abstract

The macroscopic description of the hysteretic behavior of two-phase flow in porous media remains a challenge. It is not obvious how to represent the underlying pore-scale processes at the Darcy-scale in a consistent way. Darcy-scale thermodynamic models do not completely eliminate hysteresis and our findings indicate that the shape of displacement fronts is an additional source of hysteresis that has not been considered before. This is a shortcoming because effective process behavior such as trapping efficiency of CO2 or oil production during water flooding are directly linked to pore-scale displacement mechanisms with very different front shape such as capillary fingering, flat frontal displacement, or cluster growth. Here we introduce fluid topology, expressed by the Euler characteristic of the nonwetting phase (χn), as a shape measure of displacement fronts. Using two high-quality data sets obtained by fast X-ray tomography, we show that χn is hysteretic between drainage and imbibition and characteristic for the underlying displacement pattern. In a more physical sense, the Euler characteristic can be interpreted as a parameter describing local fluid connectedness. It may provide the closing link between a topological characterization and macroscopic formulations of two-phase immiscible displacement in porous rock. Since fast X-ray tomography is currently becoming a mature technique, we expect a significant growth in high-quality data sets of real time fluid displacement processes in the future. The novel measures of fluid topology presented here have the potential to become standard metrics needed to fully explore them.

Original languageEnglish
Pages (from-to)2194-2205
Number of pages12
JournalWater Resources Research
Volume52
Issue number3
DOIs
Publication statusPublished - 1 Mar 2016
Externally publishedYes

Keywords

  • hydrology
  • integral geometry
  • multiphase flow
  • oil recovery

Fingerprint Dive into the research topics of 'Pore-scale displacement mechanisms as a source of hysteresis for two-phase flow in porous media'. Together they form a unique fingerprint.

Cite this