Page 84 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

79: Reservoir Engineering
,
830
-
840
- MINIMUM OF 22%
850 CONNATE WATER
860 -
870 -
-
880
= 890 -
8
J
> 910 -
w
w 6
A 920 - QDATA FROM
4 930 - ELECTRIC LOGS
W ~
v)
3: 940 -
3 950 -
w
m 960 -
I
970 -
w

990
IO00
I010
1020
0 10 20 30 40 50 60 70 80 90 100
WATER SATURATION (calculated 1, 96
Figure 5-49. Comparison of water saturations from capillary pressure and
electric logs [48].

thickness where saturation changes from 100% water to irreducible water for a
water-oil contact, or from 100% liquid to an irreducible water saturation for a
gas-oil contact.
Effective Penneabllitles

In the previous section, "Absolute Permeability," it was stated that permeability
at 100% saturation of a fluid (other than gases at low pressure) is a characteristic
of the rock and not a function of the flawing fluid. Of course, this implies that
there is no interaction between the fluid and the rock (such as interaction
between water and mobile or swelling clays). When permeabilities to gases are
measured, corrections must be made for gas slippage which occurs when the
capillary openings approach the mean free path of the gas. Rlinkenberg [128]
observed that gas permeability depends on the gas composition and is
approximately a linear function of the reciprocal mean pressure. Figure 5-50