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valves can close. The pipelines and risers are designed with this in
mind.
Short pipeline distances is not a problem, but longer
distances may cause multiphase well flow to separate and form
severe slugs, plugs of liquid with gas in between, traveling in the
pipeline. Severe slugging may upset the separation process, and
also cause overpressure safety shutdowns. Slugging might also
occur in the well as described earlier. Slugging may be controlled
manually by adjusting the choke, or with automatic slug controls.
Further, areas of heavy condensate might form in the pipelines
[20]. At high pressure, these plugs may freeze at normal sea
temperature, e.g. if production is shut down or with long offsets.
This may be prevented by injecting ethylene glycol. Glocol
injection is not used on Njord.

Production, test and injection manifolds
Check valves allow each well to be routed into one or more
of several Manifold Lines. There will be at least one for each
process train plus additional Manifolds for test and balancing
purposes. In the diagram we show three: Test, Low Pressure and
High Pressure Manifolds. The test manifold allows one or more
wells to be routed to the test separator. Since there is only one
process train, the HP and LP manifolds allow groups of HP and LP
wells to be taken to the first and second stage separators
respectively. The chokes are set to reduce the wellhead flow and
pressure to the desired HP and LP pressures respectively.
The desired setting for each well and which wells produce
at HP and LP for various production levels are defined by reservoir
specialists to ensure the optimum production and recovery rate.

Separation
As described earlier, the well-stream may consist of Crude
oil, Gas, Condensates, water and various contaminants. The
purpose of the separators is to split the flow into desirable
fractions.

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