Page 305 - Petrophysics 2E

276 PETROPHYSICS: RESERVOIR ROCK PROPERTIES

TABLE 4.13
SUMMARY CALCUlATlONS OF IR, N*, AND 1;

0.2 46.10 2.99 103.00
0.3 17.56 2.94 32.00
0.4 8.85 2.91 14.00
0.5 5.21 2.88 7.36
0.6 3.37 2.86 4.35
0.7 2.34 2.84 2.80
0.8 1.70 2.82 1.90
0.9 1.28 2.77 1.35

equal to 2.38. Thus, the equation of this straight line is:

(c) Using this equation calculate the new IR values for selected S,
values and tabulate (Table 4.13).
(d) Calculate the water saturation coefficient n* from Equation 4.137
for the same S, values as in Step (c):

(4.143)

From Table 4.12, the arithmetic average value of Qv of the seven
samples is 0.63 meq/ml. Hence RwCeqQv = 0.386 x 2.96 x
0.63 = 0.72, and Equation 4.143 for the Shannon sandstone
becomes:

n*= (&)In(
IR (1 + 0.72/S,)

For Sw = 0.4, for instance, the corresponding resistivity index
IR from Table 4.11 is 8.85, thus:

".=(-)In( 1 1.71
1110.40 8.85 (1 + 0.72/0.40) = 2.91