The Sean gas field is a small natural gas and associated condensate field located in the UK sector of the North Sea, off the Norfolk coast.
The field The Sean gas field is a natural gas field located in the North Sea and comprises three accumulations North Sean, South Sean and East Sean. The field north-east of Bacton Norfolk and is located to the south east of the Indefatigable gas field. It is named after the four partners at the time of its discovery: Shell, Esso, Allied Chemical and National Coal Board. The gas reservoir is a Rotliegendes sandstone 170–290 feet (52–88 metres) thick at a depth of 8,300 feet (2,530 m). North Sean was discovered in April 1969 and South Sean in January 1970 both are located in UK Block 49/25. The original determination of the gas in place amounted to 425 billion cubic feet (12.4 billion cubic metres).
Development The Sean field has been developed through a number of offshore platforms. +Sean installationsPlatformFieldFunctionTypeLegsWell slotsInstalledProduction startProduction toSean PPSouth Sean Production & accommodationSteel jacket8–May and November 1985October 1986Bacton (via 30-inch 107 km pipeline)Sean PDDrilling and wellheadSteel jacket612January and November 1985October 1986Sean PP (bridge link)Sean PKCompressionSteel jacketPlanned future, never installedSean PP (bridge link)Sean RDNorth Sean Satellite wellheadSteel jacket612January and November 1985October 1986Sean PP (via 20-inch 4.7 km pipeline) The East Sean field has not been developed.
Production Production from the field began in August 1986. Sean was operated as a peak shaving field with a maximum delivery of 600 MMSCFD (million standard cubic feet per day). Processing facilities comprise 3-phase separation and gas dehydration. Gas and associated condensate are transported via a 30-inch diameter pipeline to the Shell processing facility at the Bacton gas terminal, Norfolk.
The specification of third party gas for entry into the export gas pipeline was as follows:Shell, Sean Complex Infrastructure Information Fact Sheet, January 2015 ParameterValueGross calorific value37–44.5 MJ/Sm3Oxygen<0.2%CO22 mol % maximumH2S<3.3 ppmTotal sulfur<15 ppmWobbe Index48–51.5 MJ/Sm3Inerts<7%Nitrogen<5% In June 2015 Oranje-Nassau Energie (ONE) acquired a 50% interest in the Sean field from Shell. SSE E&P UK holds the remaining 50% interest. ONE became the operator of Sean.
See also
Indefatigable gas field
References