# Difference between revisions of "Dictionary:Dar Zarrouk"

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(dar zar ruk') The name given by Maillet to resistivity parameters or curves that deal with layered anisotropic materials. The dar Zarrouk variable is the transversal unit resistance (${\displaystyle \rho _{T}}$), the depth integral of the transverse resistivity perpendicular to the strata; the dar Zarrouk function is the longitudinal unit conductance (${\displaystyle {\frac {1}{\rho _{L}}}}$), the depth integral of the conductivity parallel to the strata; and the dar Zarrouk curve is a plot of the mean resistivity (${\displaystyle \rho _{T}}$) of the formation down to the depth z, plotted versus the anisotropy coefficient times ${\displaystyle z(\rho _{T}\rho _{L})^{1/2}}$:

${\displaystyle \rho _{T}=\sum \rho _{i}z_{i}\ {\text{and}}\ {\frac {1}{\rho _{L}}}=\sum {\frac {z_{i}}{\rho _{i}}}}$

where ${\displaystyle z_{i}}$ are layer thicknesses.[1]

## References

1. Maillet, R., 1947, The fundamental equations of electrical prospecting: Geophysics, 12, 529–556.