Oil and gas production handbook An introduction to oil ... - ABB Group

As an example, about 150 MW in compressor power is required to transport
70 mill scm/day though the 1166 km Langeled pipeline with a starting
pressure of 250 Ormen Lange Nyhamna. The initial section is 42 in, which
increases to 44 in at Sleipner, a little more than halfway (627 km from
Nyhamna, 540 km from Easington, UK), where the intermediate pressure is
155 bar maximum.
The 1200 km Northstream pipeline from Russia (Portovaya, Vyborg) to
Germany (by Hannover), has two parallel pipes of almost the same
dimensions, pressure and compression power each as Langeled.
Figure 11. Gas pipeline
Block valve stations (or vine valve stations) are required to allow closure of
off flow at regular intervals to limit accidental release of gas in case of
pipeline rupture. This will be determined by the maximum permissible
released gas volume. A valve station is normally operated by remote
telemetry and in addition to the closing valve, at least contains pressure,
temperature and some level of flow measurement. These will feed back into
the pipeline modeling system. Even if methane (CH 4 ) is lighter than air and
will rapidly rise, other gases such as propane (C 3 H 8 ) are present in up to 8%
by volume, and are heavier than air. They will sink, and rapidly create a large
volume of combustible gas mixture.
In cases where multiple producers and pipelines feed into a larger pipeline
grid, the pressure balancing to maintain required flow and observe
contractual volume allocations back to individual production sites presents
additional challenges for the pipeline balancing system.
5.4.3 Liquid pipelines, pump and valve stations
Liquid crude or product pipelines are handled much the same way, with
pump stations and block valve stations along the pipeline. However, when
the pipeline goes up or down over hills and mountains, they behave
differently. Liquid, due to the much higher specific gravity, will experience
much higher pressure drops uphill, and increases downhill, than gas. This
often requires additional pumping capacity uphill and corresponding
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