Page 249 - Petrophysics
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222 PETROPHYSICS: RESERVOIR ROCK PROPERTIES
Formatlon Factor vs Porosity
For Range of Measured Cementation Factor
0.001 0.01 0.1 1.0
Porosity( I#I ):Fraction
Formatlon Factor vs Porosity
liiustratinrr Variation in intercent ‘a
1
0. 0
Porosity (4): Fraction
Figure 4.12. Comparison of Humble and Archie equations (courtesy of Core
Laboratories).
The Humble formula and Archie formula for various values of the
cementation factor m and constant a are compared graphically in
Figure 4.12.
EXAMPLE
A cylindrical core sample of a well-consolidated sand is 100% saturated
with a NaCl brine of 34,000 ppm salinity. At 120°F, the resistance of
