Page 93 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

Basic Principles, Definitions, and Data 81

and provided more constant internal conditions. Both gas-oil and water-oil
relative permeabilities were obtained. Some of the water-oil relative permeability
data, all started at the same water saturation and obtained with the Penn State
steady-state method, are reproduced in Figure 5-57. As the contact angle was
increased to create more oil-wet conditions the effective permeability to oil
decreased. Because of the differences in flow paths for the different wettability
conditions, oil-wet systems had lower k, and higher k, when compared to water-
wet conditions at the same water saturation. As the level of oil-wetting increased,
k, at any saturation decreased whereas krw increased.

CONTACT ANGLE
---- 0'
..... 4f0
goo
............ ".I
I-
138'
------"--Y-

0 20 40 60 80 I00
WATER SATURATION. '/o PORE SPACE
Figure 5-57. Effect of wettability on water-oil relative permeabilities [I 741.