Page 285 - Geology and Geochemistry of Oil and Gas

MODELS OF STATIC GEOLOGIC SYSTEMS 247
TABLE 11.10

Kinematic viscosity of crude oils (in cst) as related to density and temperature
3
Average density (g/cm ) Temperature (1C)
10 20 30 40 50

0.82 5.6 4.2 2.8 2.8 1.4
0.83 5.6 5.6 4.5 3.9 2.5
0.84 11.2 9.9 5.6 5.4 4.3
0.85 14.0 12.9 7.9 5.8 5.2
0.86 20.5 13.7 9.4 6.5 5.6
0.87 22.4 20.3 12.4 10.5 7.6
0.88 39.2 23.2 18.3 11.7 10.3
0.89 53.0 32.6 21.9 14.4 11.0
0.90 86.4 50.3 30.9 22.7 15.1
0.91 118 94.5 50.5 30.2 24.1
0.92 — 133 89.2 53.7 33.6
0.93 — 356 178 111 55.8
0.94 — — 178 178 89.2

where T is the temperature (in 1C), n o is the kinematic viscosity (in cst) at T ¼ 01C,
which is equal to
n o ¼ a expðcgÞ (11.67)
3
where g is the crude oil density (in g/cm ) and a and c are empirical coefficients, a
being the crude oil viscosity when T ¼ 0 and g ¼ 0. The numerical coefficient b in
Eq. 11.66 also depends on the crude oil density according to the following equation:

b ¼ mg n (11.68)
where m and n are numerical coefficients that can be estimated from the experimental
data.
Substituting Eqs. 11.67 and 11.68 into Eq. 11.66, one obtains

n ¼ a expðcg mgT þ nTÞ (11.69)
or, after taking logarithms, one can obtain the equation in the following form
lg n ¼ a o þ a 1 g a 2 gT þ a 3 T (11.70)
Coefficients a i in Eq. 11.70 are calculated from the data presented in the corre-
lation tables and Figs. 11.22 and 11.23.
Substituting numerical values of coefficients a i into Eq. 11.70, one obtains
lg n ¼ 16:6g 0:100gT þ 0:072T 12:8 (11.71)
In SI units Eq. 11.71 becomes
lg n ¼ 0:0166g 0:0001gT þ 0:072T 12:8 (11.72)
2
3
where g is in kg/m , T is in 1C, and n is in m /sec.