Indefatigable gas field

The Indefatigable gas field is a large natural gas and associated condensate field located under the North Sea 60 miles (98 km) off the Norfolk coast.

Indefatigable gas field
CountryUnited Kingdom
RegionSouthern North Sea
Location/blocks49/18, 49/19, 49/23, 49/24
Offshore/onshoreOffshore
Coordinates53°19′19″N 2°34′30″E
OperatorsAmoco, Perenco, Shell
Field history
Discovery1966
Start of development1970
Start of production1971
Peak of production1976-1980
Production
Peak of production (gas)740 million cubic feet per day (21×10^6 m3/d)
Producing formationsRotliegendes sandstone

The field

The indefatigable gas field is a natural gas field located in the North Sea. The field is 67 miles (107 km) north-east of Great Yarmouth and is named after the Indefatigable Banks a shallow sand bank beneath which it is situated.[1] The gas reservoir is a Rotliegendes sandstone 200–300 feet (61–91 m) thick at a depth of 8000–9000 feet (2440–2740 m). [2] [3]It was discovered in June 1966 and extends over several blocks: 49/18, 49/19, 49/23 and 49/24. The original determination of the gas in place amounted to 126 billion cubic metres.[1] Blocks 49/18 and 49/23 were originally licensed to Amoco (since 2003 to Perenco UK Limited) and Block 49/19 and 49/24 to Shell. Production from the field began in September and October 1971. Gas and associated condensate are produced via the Leman gas field to the Bacton Gas terminal, Norfolk.

The Indefatigable gas composition and properties are as follows.[4]

Composition %
Methane 91.8
Ethane 3.39
Propane 0.85
i-butane 0.16
n-butane 0.20
i-pentane 0.07
Hexanes 0.06
Heptanes plus 0.16
Nitrogen 2.73
Carbon dioxide 0.52
Hydrogen sulfide Nil
Gas gravity 0.61 %
Mean condensate content 3.0 bbl/million cubic foot
Btu rating 1015 Btu/cubic foot

Baird gas field

The Baird gas field is located in Block 49/23 and is licensed to Perenco (originally Amoco). It was discovered in September 1993 and has recoverable reserves of 1.82 billion cubic metres.[1] Gas is produced via a seabed well assembly and a pipeline to Inde 49/23 D. The peak production was 0.66 billion cubic metres per year.[1]

Development

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

The Inde installations developed by Amoco, now owned by Perenco, were:

Perenco (former Amoco) Inde installations
Installation Location Block Platforms Function Type Legs Well slots Installed Production start Production to
Inde A Complex 49/18 Inde AD Drilling Steel jacket 8 12 July 1970 September 1971 Inde AT
Inde AP Production Steel jacket 8 – 1970 September 1971
Inde B Complex 49/18 Inde BD Drilling Steel jacket 8 12 1973 June 1974 Inde AT
Inde BP Production Jackup 4 – 1973 June 1974
Inde C Complex 49/23 Inde CD Drilling Steel jacket 8 12 August 1976 July 1977 Inde AT
Inde CP Production Steel jacket 8 – 1976 July 1977
Inde Compression 49/23 Inde AT Pipeline terminal Steel jacket 6 – May 1971 September 1971 Leman 49/27B
Inde AC Compression Steel jacket 12 – Jacket June 1979, topsides Summer 1980 November 1980 –
Inde AQ Accommodation Steel jacket 4 – June 1979 – –
Inde D 29/23 Inde D Wellheads and production Steel jacket 4 4 1990 1990 Inde C

The Perenco Indefatigable 49/23A complex also receives gas from other fields and third parties:

  • Bessemer (49/23E) installation and its satellite N.W. Bell (49/23-9) via a 14.5 km 16-inch pipeline.
  • Wenlock (49/12A) installation owned by Alpha Petroleum via a 36.231 km 8-inch pipeline. A three well-slot installation was installed in the Wenlock field in 2006 with wells commissioned in 2007, 2008 and 2009. Production declined quickly and make the installation uneconomic and a Decommissioning Programme  application was submitted to the Oil & Gas Authority in 2021.[5]
  • Davy (49/30A) installation and its satellites Davy North (49/30A-7A) and Davy East (53/5B-7) via a 43 km 16-inch pipeline.


The Inde installations developed by Shell were:

Shell Inde installations
Installation Location Block Platforms Function Type Legs Well slots Installed Production start Production to
Inde J Complex 49/24 Inde JD Drilling/production Steel jacket 8 6 June 1970, April 1971 September 1971 Inde AT
Inde JP Satellite (accommodation) Steel jacket 4 – April 1972 – –
Inde K Platform 49/24 Inde K Drilling/production/ accommodation Steel jacket 10 6 July 1971, June 1972 March 1973 Inde AT
Inde L Platform 49/24 Inde L Drilling/production Steel jacket 6 6 February 1977 October 1978 Inde K
Inde M Platform 49/19 Inde M Drilling/production Steel jacket 4 4 Spring 1985 October 1985 Inde J
Inde N Platform Inde N Drilling/production Steel jacket 4 4 1980's Inde K

Production from the Shell Inde field ceased in 2005, Inde J, K, L, M, and N were subsequently decommissioned and removed.[6]

Production

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

See also

References
  1. Department of Trade and Industry (1994). The Energy Report. London: HMSO. pp. 29, 60, 61. ISBN 0115153802.
  2. Tiratsoo, E. N. (1972). Natural Gas. Beaconsfield: Scientific Pres.
  3. Geological Society London (2003). "The Indefatigable Field, Blocks 49/18, 49/19, 49/23, 49/24, UK North Sea". lyell. Retrieved 23 September 2021.
  4. Oilfield Publications (1985). The North Sea Platform Guide. Ledbury: Oilfield Publications Limited. pp. 339–359.
  5. "Wenlock Decommissioning Programmes" (PDF). assets.publishing.service.gov.uk. Retrieved 9 December 2021.
  6. Shell (2014). "Indefatigable Field Platforms and Pipelines Decommissioning Programme Close Out Report" (PDF). gov.uk. Retrieved 25 September 2012.
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