Permeability


The same hypothesis as for the porosity are used here and some others are added as follows

  The fractures length is supposed "infinite" or in reality (if two fracture systemsexist) long enough to intercept always an other (dead ends are not considered).

  Concerning that hypothesis one should be surprise, but some recent research works show that when at least two systems of fractures exist and if their frequencies reach ÷ 4 F/m the influence of their length (>1m) could easily be neglected. Especially when compared with the incertitude on the opening on the permeability.

  The flowing is generally regarded as non turbulent and the Darcy law is used, but in the case of gas, we use a transition zone of flowing (non laminar) and the formula of LOMIZE is used.
 
A medium relative rugosity coefficient is used for oil and high for gas.

  The computing codes used to introduce the fractures frequency are whose from the permeability tensor theory which  give an accurate approximation of the reality and are scientifically commonly recognized as reliable regarding their limited hypothesis).

 



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