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| Titel |
Permeability models of porous media: Characteristic length scales, scaling constants and time-dependent electrokinetic coupling |
| VerfasserIn |
Paul Glover, Emile Walker |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250033614
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| Zusammenfassung |
| Four important models that describe the fluid permeability of geological porous media and
that are derived from different physical approaches have been rewritten in a generic form that
implies a characteristic scale length and scaling constant for each model. The four models
have been compared theoretically and using experimental data from 22 bead packs and
188 rock cores from a sand-shale sequence in the UK sector of the North Sea. The
Kozeny-Carman model did not perform well because it takes no account of the connectedness
of the pore network, and should no longer be used. The other three models (Schwartz, Sen
and Johnson (SSJ), Katz and Thompson (KT) and the so-called RGPZ) all performed well
when used with their respective length scales and scaling constants. Surprisingly,
we have found that the SSJ and KT models are extremely similar, such that their
characteristic scale lengths and scaling constants are almost identical even though they
are derived using extremely different approaches; the SSJ model by weighting the
Kozeny-Carman model using the local electric field, the KT model using entry radii from
fluid imbibition measurements. The experimentally determined scaling constants for
each model were found to be cSSJ - cKT - 8/3 - cRGPZ/3. Use of these
models with AC electrokinetic theory has also allowed us to show that these scaling
constants are also related to the a value in the RGPZ model and the m* value in
time-dependent electrokinetic theory, and then derive a relationship between the
electrokinetic transition frequency and the RGPZ scale length, which we have validated using
experimental data. The practical implication of this work for permeability prediction is
that the Katz and Thompson model should be used when fluid imbibition data is
available, while the RGPZ model should be used when electrical data is available. |
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