Empirical relationships between the [[formation resistivity factor]] F, [[porosity]] f, [[water saturation]] S<sub>w</sub> , and resistivities in [[clean]] granular rocks.

{{:terms:p11f1.gif}}

{{:terms:p11f2.gif}}

{{:terms:p11f3.gif}}


where\\
m	=	[[porosity exponent]],\\
R<sub>o</sub>	=	[[resistivity]] of the [[formation]] when 100% 
saturated with [[formation water]],\\
R<sub>w</sub>	=	formation water resistivity,\\
R<sub>t</sub>	=	[[true resistivity]] of the formation,\\
n	=	[[saturation exponent]].