Page 94 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

82 Reservoir .Engineering

Craig [ 1331 has presented typical relative permeability curves, such as given
in Figure 5-58, to point out differences in strongly water-wet and strongly
oil-wet conditions. Craig suggests that several rules of thumb can help in
distinguishing wetting preferences; typical characteristics of water-oil relative
permeability curves are given in Table 5-18 [ 1331. Additionally, the strongly oil-
wet relative permeability curves tend to have more curvature. Craig suggests the
generality that relative permeability curves of intermediate wettability systems
will have some of the characteristics of both water-wet and oil-wet conditions.

z
0 1.0
b
0.8
i
t
d 0.6
m
a
W
f 0.4
W
a
W
2 0.2
+
a
-I
W
K O
0 20 40 60 80
WATER SATURATION, % PV
Strongly water- wet rock

Figure 5-58. Strongly water-wet and strongly oil-wet relative permeability
curves [133].