Hewett gas field

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Hewett gas field
CountryUnited Kingdom
RegionSouthern North Sea
Location/blocks48/28, 48/29, 48/30, 52/4, 52/5
Offshore/onshoreOffshore
Coordinates 53°01′03″N1°47′43″E / 53.01750°N 1.79528°E / 53.01750; 1.79528
OperatorPhillips Petroleum (1966-2000), Tullow Oil (2000-2008), Eni UK (2008- )
Field history
Discovery1966
Start of development1967
Start of production1969
Peak of production1976
Production
Current production of gas819×10^6 cu ft/d (23.2×10^6 m3/d)
Recoverable gas3,500×10^9 cu ft (99×10^9 m3)
Producing formationsBunter sandstones

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.

Contents

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. [1] 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). [2] 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. [1] 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. [3] The end of production is scheduled for late 2021. [3]

The Hewett gas compositions and properties are as follows. [4]

Hewett gas properties
CompositionMiddle Bunter %Lower Bunter %
Methane86.5792.13
Ethane4.873.56
Propane1.400.85
Butane and Pentane0.320.56
Nitrogen6.572.36
Carbon dioxide0.090.02
Hydrogen sulfide500 ppmNil
Gas gravity0.655%0.607%
Mean condensate content3.2 bbl/million cu ft4.8 bbl/million cu ft
Btu rating1011 Btu/cu ft1047 Btu/cu ft

Development

The Hewett field has been developed through a number of offshore installations. [4] [5]

Hewett gas field installations
InstallationLocation BlockFacilityFunctionTypeLegsWell slotsInstalledProduction startProduction to
Hewett 52/5 A52/5PlatformDrilling & productionSteel jacket88September 1967September 1969FTP
Hewett 48/29 A48/29Platform, bridge linked to FTPDrilling & productionSteel jacket128May 1968July 1969FTP
Hewett 48/29 B48/29PlatformDrilling & productionSteel jacket88August 19721973FTP
Hewett 48/29 C48/29PlatformDrilling & productionSteel jacket8819761976FTP
Hewett FTP48/29Platform, bridge linked to 48/29 AField terminal platformSteel jacket81968July 1969Bacton
Hewett 48/29 Q48/29Platform, bridge linked to 48/29 AAccommodationSteel jacket4
Other fields producing via Hewett
Deborah48/30SubseaProductionSubsea wellhead11979197948/29 C
Little Dotty48/30SubseaProductionSubsea wellhead11979197948/29 A
Della48/30SubseaProductionSubsea wellhead11988November 198848/29 A
Delilah48/30SubseaProductionSubsea wellhead148/29 A
Area B48/30SubseaProductionSubsea wellhead1FTP
Dawn48/29SubseaProductionSubsea wellhead148/29 C
48/30 & 30/10SubseaProductionSubsea wellhead248/29 C

Production

The annual gas production from the Hewett field (in million standard cubic feet) was: [4]

Decommissioning

In 2020 Eni submitted to the UK Government a proposal for the decommissioning of the Hewett field and its installations. [6] Production from Hewett ceased in 2021. [7]

See also

References

  1. 1 2 Department of Trade and Industry (1994). The Energy Report. London: HMSO. pp. 41, 56, Map 10. ISBN   0115153802.
  2. Tiratsoo, E. N. (1972). Natural Gas: A Study. Beaconsfield: Scientific Press Limited.
  3. 1 2 Eni (2019). "HEWETT PLATFORMS DECOMMISSIONING PROGRAMME" (PDF). gov.uk. Retrieved 25 September 2021.
  4. 1 2 3 OPL (1985). The North Sea Platform Guide. Ledbury: Oilfield Publications Limited. pp. 315–324.
  5. Hewett Field Schematic, Phillips Petroleum Company, 2000
  6. Eni (2020). "Hewett Installations decommissioning" (PDF). gov.uk. Retrieved 26 September 2020.
  7. Oil and Gas Authority. "Daily production data". gov.uk. Retrieved 27 September 2021.