Enhanced permeability due to apparent oil/brine slippage in limestone and its dependence on wettability

M. Christensen, Y. Tanino

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Abstract

End point relative permeabilities were measured in three limestones with permeabilities ranging from 0.6 to 220 mD under five wettability states established by adding different organic acids, of similar molecular structure but different alkyl chain length, to the oil phase. The altered wettability corresponding to each oil/brine pair is characterized by their dynamic contact angle on a polished calcite substrate, θw, which varied between 50° and 150°. Saturation-normalized relative permeability to oil exceeds one at θw<140° in all rock considered. The equivalent slip length, defined by modeling the porous medium as a capillary tube with the defending phase distributed as an annular film on the tube wall, was below 200 nm in all experiments. The results indicate that commonly used models of relative permeability, which assume that the maximum permeability is the single-phase permeability, underestimate oil displacement for a much wider range of contact angles than previously documented.
Original languageEnglish
Pages (from-to)6116-6123
Number of pages8
JournalGeophysical Research Letters
Volume44
Issue number12
Early online date28 Jun 2017
DOIs
Publication statusPublished - 17 Jul 2017

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Keywords

  • multiphase flow
  • slip
  • wettability
  • hydrophobic surfaces
  • relative permeability

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