PROPERTIES OF OILFIELD BRINES - Petroleum Reservoir Fluid Property Correlations - page 165

Next, calculate the solubility of methane in pure water from equation
(4.15).

(4.15)

Step 10. Calculate the solubility of methane in brine at the temperature
and pressure of interest, as follows.
Calculate coefficients λ CH 4 ,Na and ζ CH 4 ,NaCl from equations (4.16) and
(4.17), respectively, using the appropriate coefficients from table 4-11.
The functional form for the coefficients λ CH 4 ,Na and ζ CH 4 ,NaCl is similar
to that used by Duan-Mao, but pressure is in MPa, and the pressure-
squared term in equation (4.16) is independent of temperature. 24
Note that temperature in equation (4.16) is Kelvin, and pressure
is MPa.

(4.16)

(4.17)

Table 4-11. Coefficients for the modified Spivey et al. correlation for methane solubility in brine

μ l C ( o
4

)

λ CH 4 ,Na , Eq. (4.16) ζ CH 4 ,NaCl , Eq. (4.17)

, Eq. (4.19)

Coefficient RT

c 1 8.3143711 -0.80898 -3.89E-03

c 2 -7.2772168E-04 1.0827E-03

c 3 2.1489858E+03 183.85

-1.4019672E-05

c 4

c 5 -6.6743449E+05

c 6 7.6985890E-02 3.924E-04

c 7 -5.0253331E-05

c 8 -30.092013

c 9 4.8468502E+03

c 10 0 -1.97E-06

Next, calculate the methane solubility in brine, in g-mol/kg H 2 O,
from equation (4.18).

m CH 4 ,b = m CH 4 ,w EXP[-2 λ ( T , p ) m Na - ζ ( T , p ) m NaCl 2 ]

(4.18)