Page 252 - Petrophysics
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FORMATION RESISTIVITY FACTOR 225
Figure 4.14. Portion ofporous rock showing dead-end traps [9].
Figure 4.15. Portion ofporous rock showing an open or symmetry trap [g].
the dead-end type. The trap in Figure 4.15 is called an open or symmetry
trap. A general relationship between F and @f may be written as [ 1 11 :
(4.42)
@ch = @m (4.43)
where fG is defined as the internal geometry parameter of the porous
rock, and m 2 1. Combining Equations 4.42 and 4.43 gives:
This is the Rosales relationship between formation resistivity, porosity,
and cementation factor. IffG = 1, Equation 4.44 gives the Archie formula.
