Page 241 - Petrophysics 2E

2 14 PETROPWSICS: RESERVOIR ROCK PROPERTIES

R
C,, = 1.6x10bC,~~013676 = 1
l.E+Ol
I , ,
I I IIllIll I I11111l1 I I IIlLLu Ill I I/I1I,l I 1 I,,,,
IIIII I I IIILIL 1 I IIIIIII I I ~IIIIH I I IIII~. 1 1
,
1
, I1,IIlU , , Ill , ,
I I iiiiii
I I IIIIIII I I Will I I,,,,,, I i iiii I IHIiP i I iiii

4.69 x respectively. Conversion of ppm to mol& and vice versa,
is straightforward when using Equation 4.17. Once Csm is calculated, X,
and then Rw25 are calculated as discussed in steps 4 and 5 of the previous
procedure.
Another alternative to the iterative procedure for converting ppm to
mol/L is to use the following correlation:

Csm = 15.9604 x 10- 6 C,, 1.013575 (4.18)

This correlation is obtained by substituting assumed values of Csm
into Equation 4.16 and then calculating the corresponding values of C,,
from Equation 4.15. Values of Csm and C, are plotted on a log-log graph
and then curve-fitted, as shown in Figure 4.6. The relationship between
Csp and Csm on a log-log graph is practically a straight line. In many cases
water, resistivity at reservoir temperature, Rfl is estimated from wireline
logs. To convert this resistivity value to concentration, first convert Rfl
to Rw25 using Arp's Equation 4.14, and then use the following equation
to calculate Csm:

(4.20)