Page 134 - Handbook Of Multiphase Flow Assurance

130 5. Flow restrictions and blockages in operations

1000

100

Pressure (bar) 4

10

1
–10 –5 0 5 10 15 20 25 30
Temperature (°C)
FIG. 5.23 Hydrate stability conditions. Redrawn from Makogon Y.F., Sarkisyants G.A., 1966. Prevention of Hydrate
Formation in Production and Transport of Gas. Nedra Publisher, Moscow, 188 pp.

We reproduce the Katz method in Fig. 5.23 below to facilitate a quick estimate of hydrate
stability from known gas gravity in absence of a computer software or a calculator. As a check
point, methane hydrate stability at 0 °C is 26 bar.
Makogon and Shalyaho (1972) and Makogon (1974, 1981, 1997) provided a simple
equation method for the gas specific gravity range of 0.6–1 for hydrocarbon hydrates
from 0 to 25 °C:
kT C]) )
° [ (
[
logP bar] = β + 0 0497 TC]+ ( ° [ 2
.
Graphs for the coefficients β and k were digitized and fitted by Elgibaly and Elkamel (1997)
−
.
.
.
β = 2 681 3 811SG +1 679SG 2
+
.
k =−0 006 0 011SG + 0 011SG 2
.
.