# Leman gas field

The Leman gas field is a natural gas field located in the North Sea 30 miles (48 km) northeast of Great Yarmouth, United Kingdom. Named after the Leman Sandbank beneath which it is situated, the gas reservoir is a 18 miles (29 km) long, 5 miles (8.0 km) wide, 800 ft (240 m) thick Rotliegendes sandstone reservoir at a depth of about 6,000 ft (1,800 m).
Following its discovery in August 1966, the reservoir was divided into blocks 49/26 and 49/27 to facilitate the licensing of mineral rights. Block 49/26 has been licensed to Shell since the beginning, with Block 49/27 originally licensed to the Amoco-Gas Council joint venture before being transferred to Perenco UK Ltd. Production of natural gas and condensates began in 1968, with both products sent via pipeline systems to the Bacton Gas Terminal on the coast of Norfolk for international distribution.
The initial total proven reserves of the Leman gas field were around 11 trillion ft$^3$ (316 km$^3$), with a production rate of around 200 million ft$^3$/day (5.7×10$^5$ m$^3$).

## Development

The Shell Leman 49/26A (AD1, AD2, AP & AK) installation began production in August 1968. It had initial recoverable reserves of 292 billion m$^3$. It is connected to the Shell terminal at Bacton. Leman 49/26B (BT & BH) and 49/26B (BP & BD) began production in November 1970. Leman 49/26C (CD & CP) began in February 1972. Leman 49/26D began in August 1974. Leman 49/26E started in August 1983. Leman 49/26F and 49/26G began in September 1987. The Leman complex of platforms are connected to Bacton via Leman 49/26A, which is east of the Hewett complex. A decommissioned 36-inch pipeline formerly delivered gas from Leman 49/26BT to Bacton. Gas and condensate is piped to Bacton via Leman 49/26A Complex (AK, AP, AD1 and AD2).
The installations developed by Shell were:
Shell Leman installations :
| Installation | Location Block | Platforms | Function | Type | Legs | Well slots | Installed | Production start | Production to |
| Leman A Complex | 49/26 | Leman AD1 | Drilling | Steel jacket | 12 | 20 | June 1967 | August 1968 | |
| Leman A Complex | 49/26 | Leman AD2 | Drilling | Steel jacket | 4 | 3 | September 1969 | 1970 | |
| Leman A Complex | 49/26 | Leman AP | Production | Steel jacket | 12 | – | August 1967 | August 1968 | Bacton, Leman BT |
| Leman A Complex | 49/26 | Leman AK | Compression (900 MMSCFD) | Steel jacket | 8 | – | February 1975 | 1975 | |
| Leman B Complex | 49/26 | Leman BD | Drilling | Steel jacket | 12 | 24 | June 1969 | November 1970 | |
| Leman B Complex | 49/26 | Leman BP | Production (500 MMSCFD) | Steel jacket | 8 | – | December 1969 | November 1970 | Leman BT |
| Leman C Complex | 49/26 | Leman CD | Drilling | Steel jacket | 12 | 20 | 1971 | February 1972 | |
| Leman C Complex | 49/26 | Leman CP | Production (650 MMSCFD) | Steel jacket | 8 | – | 1971 | February 1972 | Leman BT |
| Leman D platform | 49/26 | Leman D | Drilling, production (500 MMSCFD) and accommodation | Steel jacket | 12 | 19 | 1971/3 | September 1974 | Leman BT |
| Leman E platform | 49/26 | Leman E | Drilling, production (240 MMSCFD) and accommodation | Steel jacket | 6 | 10 | January 1982 | September 1983 | Leman BP |
| Leman F platform | 49/26 | Leman F | Drilling, production and accommodation | Steel jacket | | | | | Leman AP |
| Leman G platform | 49/26 | Leman G | Drilling, production and accommodation | Steel jacket | | | | | Leman F |
| Leman BT BK BH Complex | 49/26 | Leman BT | Field terminal | Steel jacket | 6 | – | June 1970 | | Bacton |
| Leman BT BK BH Complex | 49/26 | Leman BK | Compression (900 MMSCFD) | Steel jacket | 8 | – | February 1975 | 1975 | |
| Leman BT BK BH Complex | 49/26 | Leman BH | Accommodation | Steel jacket | 4 | – | February 1981 | – | – |
The Shell Leman 49/26A complex also receives gas from the Corvette CV installation (Block 49/24) via a 36.6 km, 20-inch pipeline.
Block 49/27 of the Leman field is licensed to, and operated by, Perenco UK Ltd, originally by the Gas Council-Amoco. BP took over the interests of Amoco in 1998 and operated as BP-Amoco, subsequently BP. Perenco UK Ltd took over the interests of BP in the Leman and Indefatigable fields and BP plant at Bacton in 2003. The field had initial recoverable reserves of 292 billion m$^3$. It comprises the following installations, platforms and complexes: Leman 49/27A (AD, AP, AC, AQ, AX); 49/27B (BD, BP, BT); 49/27C (CD, CP); 49/27D (DD, DP); 49/27E (ED, EP); 49/27F (FD, FP); 49/27G; 49/27H; and 49/27J. Gas is routed to Bacton via two 30-inch pipelines from Leman 49/27A and Leman 49/27B.
The Leman installations developed by Amoco, now owned by Perenco, were:
Amoco (now Perenco) Leman installations :
| Installation | Location Block | Platforms | Function | Type | Legs | Well slots | Installed | Production start | Production to |
| Leman A Complex | 49/27 | Leman AD | Drilling | Steel jacket | 8 | 12 | August 1967 | Easter 1969 | Leman AP |
| Leman A Complex | 49/27 | Leman AP | Production | Steel jacket | 6 | – | July 1968 | Easter 1969 | Leman AC |
| Leman A Complex | 49/27 | Leman AC | Compression (900 MMSCFD) | Steel jacket | 8 | – | 1975 | October 1976 | Bacton |
| Leman A Complex | 49/27 | Leman AQ | Accommodation | Steel jacket | 4 | – | March 1984 | – | – |
| Leman A Complex | 49/27 | Leman AX | Compression (LP) | Steel jacket | | | 1988 | 1989 | Leman AC |
| Leman B Complex | 49/27 | Leman BD | Drilling | Steel jacket | 8 | 12 | May 1968 | | Leman BP |
| Leman B Complex | 49/27 | Leman BP | Production (171 MMSCFD) | Steel jacket | 6 | – | August 1968 | | |
| Leman B Complex | 49/27 | Leman BT | Field Terminal | Steel jacket | 6 | – | April 1970 | | Bacton |
| Leman C Complex | 49/27 | Leman CD | Drilling | Steel jacket | 8 | 12 | 1967 | 1969 | |
| Leman C Complex | 49/27 | Leman CP | Production (292 MMSCFD) | Steel jacket | 6 | – | 1967 | 1969 | Leman AP |
| Leman D Complex | 49/27 | Leman DD | Drilling | Steel jacket | 8 | 12 | 1972 | 1973 | |
| Leman D Complex | 49/27 | Leman DP | Production (300 MMSCFD) | Jack up | 6 | – | 1973 | 1973 | Leman BT |
| Leman E Complex | 49/27 | Leman ED | Drilling | Steel jacket | 8 | 12 | 1972 | 1974 | |
| Leman E Complex | 49/27 | Leman EP | Production (80-90 MMSCFD) | Steel jacket | 4 | – | 1974 | 1974 | Leman AP |
| Leman F Complex | 49/27 | Leman FD | Drilling | Steel jacket | 8 | 12 | 1973 | 1975 | |
| Leman F Complex | 49/27 | Leman FP | Production (337 MMSCFD) | Jack up | 6 | – | 1975 | 1975 | Leman BT |
| Leman G platform | 49/27 | Leman G | Production (300 MMSCFD) | Steel jacket | | 12 | 1985 | October 1985 | Leman BT |
| Leman H platform | 49/27 | Leman H | Production (250 MMSCFD) | Steel jacket | 4 | 4 | 1984 | 1985 | Leman J |
| Leman J platform | 49/27 | Leman J | Production (250 MMSCFD) | Steel jacket | 4 | 4 | 1984 | 1985 | Leman A |
The Perenco Leman 49/27A complex also receives gas from the Camelot CA installation (Block 53/1a) via a 14.5 km, 12-inch pipeline.
In the mid-1990s the glycol dehydration facilities of several installations in the Inde and Leman fields was decommissioned. This enabled the installations to become normally unattended installations (NUIs) reducing manning costs and the risks to personnel.

## Production

The Leman gas composition and properties are as follows.
| Composition | % |
| Methane | 95.05 |
| Ethane | 2.86 |
| Propane | 0.49 |
| i-butane | 0.08 |
| n-butane | 0.09 |
| i-pentane | 0.03 |
| n-pentane | 0.02 |
| Hexanes | 0.02 |
| Heptanes plus | 0.04 |
| Nitrogen | 1.26 |
| Helium | 0.02 |
| Carbon dioxide | 0.04 |
| Hydrogen sulphide | Nil |
| Total sulphur | <0.5 |
| Gas gravity | 0.585% |
| Mean condensate content | 1.13 bbl/cubic foot |
| Btu rating | 1024 Btu/ cubic foot |
The annual gas production from the Shell Leman field (in million standard cubic feet) was:
The annual gas production from the Amoco Leman field (in million standard cubic feet) was: