Hewett gas field

The Hewett gas field is a large natural gas and associated condensate field located under the North Sea 19 miles (30 km) off the Norfolk coast.

The field The Hewett gas field is a natural gas field located in the UK North Sea. The field is named after the Hewett Ledges a sand bank feature beneath which the field is situated. The gas reservoir is a Lower Triassic (Middle and Lower Bunter) sandstone and a Permian Zechstein carbonate bed at a relatively shallow depth of 3,000–4,200 feet (914–1,280 m). The Hewett structure runs north-west to south-east and is about 18 miles long and 3 miles wide (29 km by 4.8 km). It was discovered in October 1966 and extends over blocks: 48/28, 48/29, 48/30, 52/4 and 52/5. To the north are the Big Dottie, Little Dottie and Deborah accumulations, which are separate from Hewett, but are produced through the Hewett topsides facilities. The original determination of the gas in place amounted to 115 billion cubic metres. The field was originally licensed to Phillips Petroleum Exploration UK Ltd (then from 2001 Tullow Oil UK Ltd and from 2008 Eni UK Ltd). Production from the field began in July 1969. Gas and associated condensate are exported from the field via two 30 inch diameter pipelines to the Bacton gas terminal, Norfolk. Eni submitted plans in 2019 to decommission the Hewett field and to remove all installations. The end of production is scheduled for late 2021.

The Hewett gas compositions and properties are as follows. +Hewett gas propertiesCompositionMiddle Bunter %Lower Bunter %Methane86.5792.13Ethane4.873.56Propane1.400.85Butane and Pentane0.320.56Nitrogen6.572.36Carbon dioxide0.090.02Hydrogen sulfide500 ppmNilGas gravity0.655%0.607%Mean condensate content3.2 bbl/million cu ft4.8 bbl/million cu ftBtu rating1011 Btu/cu ft1047 Btu/cu ft

Development The Hewett field has been developed through a number of offshore installations.Hewett Field Schematic, Phillips Petroleum Company, 2000 +Hewett gas field installationsInstallationLocation BlockFacilityFunctionTypeLegsWell slotsInstalledProduction startProduction toHewett 52/5 A52/5PlatformDrilling & productionSteel jacket88September 1967September 1969FTPHewett 48/29 A48/29Platform, bridge linked to FTPDrilling & productionSteel jacket128May 1968July 1969FTPHewett 48/29 B48/29PlatformDrilling & productionSteel jacket88August 19721973FTPHewett 48/29 C48/29PlatformDrilling & productionSteel jacket8819761976FTPHewett FTP 48/29Platform, bridge linked to 48/29 AField terminal platformSteel jacket8–1968July 1969BactonHewett 48/29 Q48/29Platform, bridge linked to 48/29 AAccommodationSteel jacket4–––Other fields producing via HewettDeborah48/30SubseaProductionSubsea wellhead–11979197948/29 CLittle Dotty48/30SubseaProductionSubsea wellhead–11979197948/29 ADella48/30SubseaProductionSubsea wellhead–11988November 198848/29 ADelilah48/30SubseaProductionSubsea wellhead–148/29 AArea B48/30SubseaProductionSubsea wellhead–1FTPDawn48/29SubseaProductionSubsea wellhead–148/29 C–48/30 & 30/10SubseaProductionSubsea wellhead–248/29 C

Production

Decommissioning In 2020 Eni submitted to the UK Government a proposal for the decommissioning of the Hewett field and its installations. Production from Hewett ceased in 2021.

Hewett gas field

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