Transport in Porous Media

, Volume 87, Issue 2, pp 561–584 | Cite as

Pore-Level Observation of Free Gravity Drainage of Oil in Fractured Porous Media

  • Vahid MashayekhizadehEmail author
  • Mohammad Hossein Ghazanfari
  • Riyaz Kharrat
  • Morteza Dejam


This work presents results from two sets of experiments conducted to study, in pore level, the role of fracture aperture and tilt angle on the stability of liquid bridges and the shape of a front during free gravity drainage process. Glass micromodels of two different aperture sizes were used to monitor the mechanism of gravity drainage of air–crude oil system, rotating around a bottom corner to create different tilting angles. Oil content within the matrix blocks was determined as a function of time using a series of images obtained during the experiments, from which net drainage rate from the upper and lower matrix blocks is calculated. Liquid bridges are more frequent but less stable at early time of drainage. The liquid bridges, which have widths as thin as 50 μm, can resist instability to maintain continuity. Liquid bridges formed in stacks with higher tilt angles are more stable, enhancing oil drainage from the upper matrix block and causing higher recoveries. Quantitative analysis of the results shows that a wider fracture aperture increases the oil production rate, but reduces the ultimate recovery. Furthermore, stacks with higher tilt angles present larger ultimate recoveries and smaller production rates. The front geometry in the lower block deviates from linearity due to formation of liquid bridges in the middle fracture. The results of this work can be helpful to better understand the interaction between fractures and matrix blocks.


Free gravity drainage Fracture aperture Fracture tilt angle Liquid bridge Front geometry Pore level Glass micromodels Oil 


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Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • Vahid Mashayekhizadeh
    • 1
    Email author
  • Mohammad Hossein Ghazanfari
    • 2
  • Riyaz Kharrat
    • 1
  • Morteza Dejam
    • 2
  1. 1.Tehran Petroleum Research CenterPetroleum University of TechnologyTehranIran
  2. 2.Department of Chemical and Petroleum EngineeringSharif University of TechnologyTehranIran

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