Page 218 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2
P. 218
Formation Evaluation 187
Example: A reservoir section at 90°C temperature and 25 MPa pressure
contains water of 175,000 ppm (NaCI) salinity: 30" API oil with
a GOR of 2000 cu fthbl, and methane gas.
Thus, Z = 87 cu (7 = 52 pi)
Z,=19cU(Z=24Op)
C, = 6.9 cu (Z = 660 pi)
300
275
250
B
;
\ 225
UJ
b 200
0
0
0
F
% 175
!E
P
2; 150
.-
.- -
S
m
'2 125
B
3
Q) - 100
.- B
s
3 75
50
25
0
Figure 5-111. Chart for finding Zw from equivalent water salinity and
formation temperature [199].
Figure 5-112, and then Figure 5-113 can be entered. Once all of the parameters
have been found, Equation 5-119 is used to find Sw.
Applications. Pulsed neutron logs are most useful for monitoring changes in
water saturation over time while a reservoir is produced. Initially, these logs
are run prior to perforating a zone. Subsequent logs are run every few months
(or years) depending on production rate and the amount of control desired.
Water saturation is calculated for each run using Equation 5-119 and subtracted
(text continued on page 190)
