Page 275 - Petrophysics 2E
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248 PETROPHYSICS: RESERVOIR ROCK PROPERTIES
Kaolinitic Sandstone
Chloritic Sandstone
0 5 10 15 20 25 30
Measured Porosity, % Bulk Volume
Figure 4.31. Permeability-porosity relationship in fine-grained and well-sorted
sandstones as a function of various clay minerals [24].
The fractional volume of sand grains is:
(4.82)
For structural shale, the effective porosity, @e, and the fractional
volume of sand grains, V,, depend on the extent to which sand grains
have been replaced clay particles. If the fractional volume of shale, Vsh,
is less than (1 - @cs) then effective porosity is equivalent to the clean
sand porosity and V,, is:
If the fractional volume of shale, Vsh, is greater than (1 - Qcs), then the
fractional volume of sand grains V, is practically zero, and the effective
porosity is:
