ENGLISH - Gassco

Gas administration
System operation and capacity management. The 23 staff in our control room average 10 years of experience. Controlling the gas flow
continues without a break around the clock. Three people work the night shift, while the day and afternoon shifts each have four operatives.
Their main duties are to manage the gas flow through constant monitoring, regulate quality and ensure that the gas blend is correct. Since
the various fields deliver different gas grades, these must be processed or mixed to achieve the desired quality before delivery to the buyer.
Such blending allows us to deliver gas with the agreed composition virtually all the time.
Our control room’s coordinatory role is extensive
and multifaceted. In certain circumstances,
we can instruct a field operator to deliver gas
for a limited period. This happens, for instance,
if a field shuts down for maintenance or other
reasons. We can then require another field to
deliver more and others to supply less. The
control room is also involved in planning shortterm
shutdowns which supplement major
scheduled turnarounds. Transport capacity de-
pends to some extent on the ambient water
temperature along the pipelines, which means
that more can be sold in the cold season. Using
good temperature information, updated daily,
and advanced computer models, we calculate the
daily extra capacity available for sale in the winter.
Planning ship calls at Kårstø also requires careful
coordination with daily gas flows.
Construction and development. A key challenge
for us as operator is to run all our facilities safely
and cost-efficiently. We are also required to make
improvements, remove operational bottlenecks
and increase accessibility in the gas transport
system. Ensuring that all Norwegian gas reaches
the market in an acceptable, safe and efficient
manner is an important and responsible job. The
value chain comprises five stages: production,
transport to land, processing, onward transport,
and sales/marketing.
Production. Gas is produced from more than 30
fixed and floating installations on the NCS.
Transport to land. Gas is piped from the NCS to
processing facilities on land. At this stage, it is
usually a blend of dry gas (methane) and natural
gas liquids (NGL – ethane, propane and butanes)
known as rich gas.
Processing. When rich gas reaches the processing
plant, its pressure is reduced before the lightest
(dry) gas and the NGL are separated in an extraction
plant. The various NGL fractions are also separated
into ethane, propane and butanes. This is
accomplished by heating the mix at the base of a
tall column, so that the lightest fraction vaporises
and collects at the top. The residue is then sent to
the next column and reheated. This fractionation
process continues until all the NGLs have been
separated out.
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The Bygnes control room.