Automated extraction of in situ contact angles from micro-computed tomography images of porous media

Anelechi Ibekwe, Dubravka Pokrajac* (Corresponding Author), Yukie Tanino

*Corresponding author for this work

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We present a simple and robust algorithm for the automated measurement of in situ contact angles from segmented micro-computed tomography images of immiscible fluid pairs in porous media and 2D slices of them. The algorithm comprises three steps: identification of contact points, an initial coarse estimate of contact angle, and its refinement. To obtain the coarse estimate we identify the vectors which point into the wetting phase and are also normal to the fluid/fluid and fluid/solid surfaces within the vicinity of each contact point. The coarse estimate is subsequently refined by fitting planes across fluid/fluid and fluid/solid surfaces to obtain the final estimate of contact angle. The algorithm was applied to a packed bed of glass spheres using air/water as the fluid pairs. A wide distribution of contact angles spanning the full range of possible values was measured for both the 2D and 3D cases. The distributions are skewed towards their respective means and are longer-tailed compared to a Gaussian distribution. The mean contact angles were found to be approximately 65±21°, which is significantly larger than bulk contact angles of 35±3° measured on a flat glass substrate using identical test fluids. The disagreement suggests that bulk contact angles can dramatically underestimate in situ contact angles even in the simplest porous media.

Original languageEnglish
Article number104425
Number of pages12
JournalComputers & Geosciences
Early online date3 Feb 2020
Publication statusPublished - 1 Apr 2020

Bibliographical note

This material contains work supported by an Aberdeen Formation Evaluation Society student bursary, a Society of Petrophysicist and Well-Log Analysts Foundation grant, and a Messel travel bursary from the Society of Chemical Industry. AI was supported by the University of Aberdeen School of Engineering Elphinstone Ph.D. studentship . The authors gratefully acknowledge Alhammadi et al. (2017) for helpful suggestions on the segmentation and Kamaljit Singh for providing unpublished in situ contact angle measurements (Fig. 11a) for oil ganglion SSa. The authors thank the two anonymous reviewers for their comments.


  • contact angle
  • wettability
  • micro-CT
  • tomography
  • multiphase flow
  • pore scale imaging
  • Wettability
  • Multiphase flow
  • Micro-CT
  • Tomography
  • Contact angle
  • Pore scale imaging


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