Page 186 - Petrophysics

PERMEABILITY-POROSITY RELATIONSHIPS 159

Assuming High Percentage Illite Model
(a) Using Equation 3.105:

0 6675
kv = 0.159 kG
kv = 0.159 (0.58)0.6675 = 0.11 mD

kH 0.58
I,=-=- = 5.27
kv 0.11

(b) Using Equation 3.107:
kv = 0.049 (E)

1.3939

kv = 0.049 (p)
1.3939
0.58
0.11 = 0-15 mD

kH 0.58
IA=-=-- - 3.86
kv 0.15

(c) Using Equation 3.1 1 1 :
kv = 2.5054 (+ (6))
0.9383

kv = 2.5054 (0.058 (E))
0.9383
= 0.37 mD

It is clear from the anisotropy values that high Illite content formations
are more anisotropic. Incorporating the porosity and grain diameter
reduces the scatter and predicts anisotropy more reliably, as confirmed
from transient pressure test analysis.

RESERVOIR HETEROGENEITY

Heterogeneity is viewed on a broader scale than anisotropy. The
degree of variation in the petrophysical properties of petroleum-bearing