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@wikipedia


One of the Absolute permeability models based on simulating the flow through the multi-pipe conduits or multi-grain pack:

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anchorCK
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k = 1014.24 \cdot {\rm FZI}^2 \cdot \frac{(\phi_f -\phi_{f0})^3}{( 1 - \phi_f+\phi_{f0})^2}
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anchorFZI
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{\rm FZI} = \frac{1}{\sqrt{F_S} \, S_{gV} \, \tau }

where

LaTeX Math Inline
body\phi

effective porosity

LaTeX Math Inline
body--uriencoded--S_%7BgV%7D = \Sigma_e/V_\phi

surface pore area per unit pore volume

LaTeX Math Inline
body\Sigma_e

pore surface area

LaTeX Math Inline
body--uriencoded--%7B\rm FZI%7D

Flow Zone Indicator

LaTeX Math Inline
bodyF_S

pore shape factor

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bodyV_\phi

pore volume


LaTeX Math Inline
body\tau

pore channel tortuosity


The alternative form is derived from the correlation which is valid in some practical cases:

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anchord
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\frac{1}{\sqrt{F_S} \, S_{gV}} \approx 0.0037 \cdot d

where

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bodyd

average grain size

so that Absolute permeability is going to be:

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anchorCZ2
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k = \frac{d^2}{72 \cdot \tau^2} \cdot \frac{(\phi_f -\phi_{f0})^3}{( 1 - \phi_f+\phi_{f0})^2}

where

LaTeX Math Inline
bodyk

absolute permeability

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body\phi_e

effective formation porosity

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body\phi_0

porosity cut-off

LaTeX Math Inline
bodyd

grain size

LaTeX Math Inline
body\tau

pore channel tortuosity



This correlation was historical the first physical permeability model, based on the fluid flow in porous media with simplified structure consisted of a bunch of independent capillaries with various diameters.

Later on it's been upgraded to percolation through inter-grain porous space which specifies the Flow Zone Indicator 

LaTeX Math Inline
bodyFZI
 as a function of grains size distribution, grain shape and packing.

The most popular correlation with a mean grain size 

LaTeX Math Inline
bodyD_g
is given as:

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anchorFXZ4L
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FZI = a \cdot D_g

where coefficient 

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bodya
 is a function of grain shape, packing, inter-grain clay and, as a consequence, of inter-grain effective porosity 
LaTeX Math Inline
body\phi
.


See also


Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petrophysics / Absolute permeability / Absolute permeability @model


References


J. Kozeny, "Ueber kapillare Leitung des Wassers im Boden." Sitzungsber Akad. Wiss., Wien, 136(2a): 271-306, 1927.