The Cygnus gas field is a
natural gas
Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon ...
reservoir and gas production facilities in the UK sector of the southern
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...
. It is about 150 km of east of the Lincolnshire coast and started gas production in 2016.
The field
The Cygnus field extends over UK offshore Blocks 44/11a and 44/12a. The field was discovered in 1988 by Marathon Oil.
The reservoirs are
Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Pale ...
Leman sandstone and
Carboniferous sandstone formations and have recoverable reserves of 760 billion cubic feet.
In 2019 the Cygnus gas field was jointly owned by Spirit Energy (61.25 %) and Neptune Energy (38.75 %), Neptune E&P UK Ltd operates the infrastructure.
Development
Production from the field has been developed in stages. In the first stage gas was produced by wells on the Cygnus Alpha platform and then routed by pipeline to the Bacton Gas Terminal via the Esmond Transmission System.
The next stage entailed development of the north west part of the field produced from the Cygnus Bravo platform which was routed 7 km to the Cygnus Alpha installation.
Details of the Cygnus field infrastructure are as shown.
Production
Cygnus gas has a minimum
Wobbe Index of 46.6 to 46.8 MJ/m
3. This is below the minimum specification for entry into the
National Transmission System (47.2 MJ/m
3). Cygnus gas en route to Bacton, commingles within the ETS pipeline with gas from Trent and Tors fields. The mixed gas arrives at Bacton with a minimum Wobbe index of 46.5 to 46.7 MJ/m
3. If there is a reduction of gas flow from the other fields that deliver gas to Bacton then the output of Cygnus is constrained. To maintain Cygnus flow a temporary reduction of Wobbe Index from 47.2 MJ/m
3 to 46.5 MJ/m
3 at the NTS entry point at Bacton terminal was agreed in 2020.
See also
*
Bacton gas terminal
*
List of oil and gas fields of the North Sea
*
Esmond, Forbes and Gordon gas fields
Esmond, Forbes and Gordon are three adjacent, now depleted, natural gas fields in the southern North Sea, 170 km east of Teesside.
The fields
Esmond, Forbes and Gordon were the most northerly gas fields in the UK sector of the southern North ...
*
Tyne, Trent and Tors gas fields
The Tyne, Trent and Tors gas fields are depleted natural gas reservoirs and former gas production facilities in the southern North Sea, centred around the Trent installation about 115 km east of Flamborough Head, Yorkshire. The fields produced gas ...
References
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Natural gas fields in the United Kingdom
North Sea energy