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 language | English |
|---|---|
| Pages (from-to) | 6116-6123 |
| Number of pages | 8 |
| Journal | Geophysical Research Letters |
| Volume | 44 |
| Issue number | 12 |
| Early online date | 28 Jun 2017 |
| DOIs | |
| Publication status | Published - 17 Jul 2017 |
Bibliographical note
AcknowledgmentsThis material includes work supported by a Society of Petrophysicists and Well Log Analysts Foundation grant and an Aberdeen Formation Evaluation Society scholarship. M.C. was supported by a University of Aberdeen College of Physical Sciences studentship. The authors gratefully acknowledge Amer Syed for his assistance with the assembly and maintenance of the coreflood rigs, Jim Anderson for helpful discussions, and the two anonymous reviewers for their comments and suggestions. All data used in this study will be made available from the corresponding author upon request.
Keywords
- multiphase flow
- slip
- wettability
- hydrophobic surfaces
- relative permeability
