Page 217 - Handbook Of Multiphase Flow Assurance

216 8. Flow assurance stability issues

Vacuum condition in flow

Vacuum condition and pressure surge may occur during stock oil flow.
In oil export pipelines going through mountainous terrain, or in deepwater during dis-
placement of the flowline live oil with stock oil there may be a vacuum condition at the high-
est point of the flow system.
If pressure at a pipeline pumping station downstream of a mountain or at the bottom of the
flowline riser is lower than hydrostatic head pressure for stock oil, vacuum may occur at the
crest of the mountain or at the riser top.
Vacuum condition has to be taken into account for design of flexible lines and flexible parts
and materials on topsides system.
Vacuum can also occur at top of chemical injection lines causing flashing off of solvent and
deposition of active ingredient in the chemical tubing.
Higher than normal flowing pressure or deadheading may occur during start-up of stock
oil flow to move the stationary fluids in the pipeline or in the flowline such as during dead
oil displacement.

References

Hill, T.J., Wood, D.G., 1994. Slug flow: occurrence, consequences and prediction. In: SPE 27960, University of Tulsa
Centennial Petroleum Engineering Symposium, Tulsa, 29–31 August.
Hou, D.Q., Tijsseling, A.S., Bozkus, Z., 2014. Dynamic force on an elbow caused by a traveling liquid slug. J. Press.
Vessel. Technol. 136.
Makogon, T.Y., Estanga, D., Sarica, C., 2011. A new passive technique for severe slugging attenuation. In: 15th
Multiphase Production Technology Conference, Cannes, France, 15–17 June.
Montgomery, J.A., 2002. Severe Slugging and Unstable Flows in an S-Shaped Riser. PhD. Thesis, Cranfield University.
Sancho, A.M., 2015. Severe Slugging in Pipelines. Master Sc. Thesis, Instituto Superior Tecnico, Lisboa.
Taitel, Y., 1986. Stability of severe slugging. Int. J. Multiphase Flow 12 (2), 203–217.
Tay, B.L., Thorpe, R.B., 2015. Statistical analysis of the hydrodynamic forces acting on pipe bends in gas–liquid slug
flow and their relation to fatigue. Chem. Eng. Res. Des. 104, 457–471.
Zakarian, E., 2000. Analysis of two-phase flow instabilities in pipe-riser system. In: Proceedings PVP2000, ASME
Pressure Vessels and Piping Conference, July 23–27, Seattle.

Further reading
Boe, A., 1981. Severe Slugging Characteristics, Part I, Flow Regime for Severe Slugging, Presented at Special Topics
in Two-Phase Flow, Trondheim, Norway.
Joukowsky, N., 1898. “Über den hydraulischen Stoss in Wasserleitungsröhren.” (“On the hydraulic hammer in water
supply pipes.”). Mémoires de l'Académie Impériale des Sciences de St.-Pétersbourg (1900), Series 8 9 (5), 1–71. (in
German); Sections presented to the Division of Physical Sciences of O.L.E., 26 September 1897, to the Physical-
Mathematical Commission of the Society, 30 January 1898, to the Polytechnic Society of the Moscow Imperial
Institute, 21 February 1898; complete paper to the Russian Technical Society, 24 April 1898, to the Physical-
Mathematical Division of the Academy of Sciences, 13 May 1898. Also: Жуковский, Н.Е. (1899). “О гидравлическом
ударе в водопроводных трубах.” (“On hydraulic hammer in water mains.”), Proc., 4th Russian Water Pipes
Congress, pp. 78–173, printed in Moscow (1901), April 1899, Odessa, Russia.