L4-L7 gas fields

The L4-L7 gas fields are significant natural gas producing fields in the Netherlands sectors L4 and L7 of the North Sea. They are operationally one complex which started producing gas from the L7 main platform hub in 1977 and was still partly operational in 2021.

L4-L7 gas fields
CountryNetherlands
RegionNorth Sea
Location/blocksL4 and L7
Offshore/onshoreOffshore
Coordinates53°32′18″N 04°12′9″E
OperatorPetroland BV, then Total
OwnerPetroland BV, then Total
Field history
Discovery1973
Start of production1977
Peak of production135 MMSCFD
Production
Recoverable gas1,470×10^9 cu ft (42×10^9 m3)

The fields

The adjacent Block L4 and L7 gas fields are located in the Southern North Sea.[1][2] The L7 gas field was discovered in 1973 and the L4 field the following year.[3] The gas reservoirs are Upper Rotliegendes sandstones, L7 lies at a depth of 12,700 feet (3,900 metres).[4] The L7 field had recoverable reserves of 1.47 trillion cubic feet.[3]

Development

The L4-L7 reservoirs were developed by a number of offshore installations across both Blocks. The L7 main platform complex was the hub of the fields, it received gas from its bridge-linked drilling/wellhead (C) and compression (PK) platforms, from L7 Block satellite platforms, and from the adjacent Block L4.[3][5][6]

L4-L7 Fields Offshore installations
Installation Coordinates Water depth Platform Function Type Legs Well slots Installed Production start Production to Status
L7 main platform complex (bridge linked) 53°32’18”N 04°12’9”E 27.5 m L7-C Platform Drilling, production Steel jacket 4 6 April 1976 June 1977 L7-P Closed
L7-P Platform Processing Steel jacket 8 – 1976 June 1977 L10 platform by 5.8 km 16-inch pipeline Closed May  2017
L7-Q Platform Accommodation Steel jacket 4 – 1976 – – Closed
L7-PK Platform Compression Steel jacket 4 – June 1982 1983 L7-P Closed May 2017
L7B Complex 53°36’32”N 04°12’24”E 34.7 m L7-B Platform Drilling, production Steel jacket 4 6 July 1975 1977 L7-P by 7.85 km 12-inch pipeline Closed
L7-BB Wellhead platform Steel jacket 4 6 September 1978 1979 Closed
L7A Satellite 53°36’01”N 04°05’01”E 34.5 m L7-A Platform Drilling, production Steel jacket 4 2 August 1984 Late 1985 L7-P by 9.8 km 10-inch pipeline Closed
L7-H 53.626389°N 4.144967°E 36 m L7-H Platform Wellhead platform Fixed steel 1989 Closed
L7-N 53.573944°N 4.176776°E 32 m L7-N Platform Wellhead platform Fixed steel 1988 Wells plugged 2015
L4-A 53°43’32”N 04°05’56”E 39.5 m L4-A Platform Drilling, production, accommodation Steel jacket 8 6 Summer 1982 1983 L7-P by 22.7 km 12-inch pipeline Operating
L4-B 53°40’36”N 04°00’06”E 38.7 m L4-B Platform Drilling, production Steel jacket 4 2 August 1984 Late 1985 L7-A by 10.6 k, 10-inch pipeline Wells plugged 2015
L4-G 53.81009°N 4.15805°E 42 m L4-G Wellhead Subsea wellhead 2006 Operating
L4-PN 53.82341°N 4.0498°E 41 m L4-PN Platform Production Fixed steel 1998 Operating

The peak production from the L7 field was 135 MMSCFD in 1978–9, and from the L4 field was 106 MMSCFD in 1983.[3] The design capacity of the process facilities on L7-P platform is 5.5 million m3/day.[3]

The field was initially operated by Petroland BV, then Total.[3][6]

Decommissioning

The status of the production facilities is given in the final column of the above table. The entire L7 field is now closed as is the L4-B Platform. Operations continue in parts of the L4 field.[6]

See also

References
  1. "Dutch Offshore Gas: a success story". Retrieved 10 October 2021.
  2. Department of Trade and Industry (1994). The Energy Report. London: HMSO. pp. Map 3. ISBN 0115153802.
  3. Oilfield Publications Limited (1985). The North Sea Platform Guide. Ledbury UK: Oilfield Publications Limited. pp. 423–33.
  4. "Fact sheet L7" (PDF). Retrieved 10 October 2021.
  5. "L7 gas fields". barellfull. Retrieved 10 October 2021.
  6. OSPAR (2017). "North Sea Offshore Installations". OSPAR. Retrieved 10 October 2021.
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