Page 166 - Petrophysics

PERMEABILITY-POROSITY RELATIONSHIPS 139

3. Calculate the intergranular porosity of the matrix ($ma) as

9t - 9u
@ma = - (3.68b)
1 - 9"

4. Estimate the average particle size, dgr, using a compactor or
micrometer.
5. Calculate the permeability of the nonvuggy matrix, kma, using
Equation 3.68.

A negligibly small increase in the permeability of the matrix (with
unconsolidated vugs) will be observed if the total porosity cPt is used
in Equation 3.68 instead of @ma. Craze and Bagrintseva demonstrated
the influence of lithology on the relationship between porosity and
permeability [37,38]. On the basis of core data from cretaceous Edward
limestone (Figure 3.28), Craze noted that as the texture changes from
microgranular to coarse-grained, the permeability increases for a given
porosity [ 371. Bagrintseva investigated the interrelationships among
various rock properties of several carbonate reservoirs in the former
Soviet Union [38].
Chilingarian et al. used Bagrintseva's data and derived several useful
correlations between permeability and porosity by considering two
additional variables: irreducible fluid saturation and specific surface

1 10 100
Interparticle Porosity, %
Figure 3.28. Relationship between porosity and permeability for various types of
cretaceous Edwards limestone [3 71.