# Arthurian gas fields

The Arthurian gas fields are small natural gas producing areas in the UK sector of the southern North Sea, their names are associated with the legend of King Arthur. The fields started gas production from 1989 and several are now depleted and have been decommissioned.

## The fields

Mobil instigated the field naming convention using characters, people, places and objects associated with the legendary British King Arthur. Mobil applied it to its gas fields across the southern North Sea. The Arthurian fields span Quadrants 48, 49 and 53 from Arthur in the south east to Excalibur in the north west.
The Arthurian fields and the reservoir parameters are as follows.
Arthurian fields reservoir parameters :
| Field | Block | Coordinates | Gas reservoir | Gas reserves (see note below) | Discovered | Original licensee(s) |
| Arthur | 53/2b 53/1d | 53.032447 2.390328 | | 3.7 bcm | 2003 | ExxonMobil |
| Avalon | 49/09b | | | 104 bcf | December 1989 | Mobil |
| Camelot North | 53/1a | | Lower Permian Leman sand Rotliegendes | 2.30 bcm | November 1967 | Mobil North Sea Ltd |
| Camelot Central South | 53/1a | | Lower Permian Leman sand Rotliegendes | 7.20 bcm | June 1987 | Mobil North Sea Ltd |
| Camelot North East | 53/2 | 52.972000 2.21444 | Permian | 0.90 bcm | March 1988 | Mobil North Sea Ltd |
| Excalibur | 48/17a 48/18a | 53.465083 1.344583 | Rotliegendes | 7.1 bcm | 1988 | Mobil North Sea Ltd |
| Galahad | 48/12 | 53.546722 1.360611 | | 153 bcf | | Mobil |
| Gawain | 49/29a | 53.171136 2.701406 | Leman sands | 196 bcf | 1970 | ARCO |
| Guinevere | 48/17b | 53.414833 1.273639 | Permian | 2.07 bcm | 1988 | Mobil North Sea Ltd (25.5%) |
| Lancelot | 48/17a 48/18a | 53.41002 1.375306 | Permian | 5.60 bcm | 1986 | Mobil North Sea Ltd |
| Malory | 48/12d | 5.543611 1.244167 | Rotliegendes | 35 bcf | 1997 | Mobil |
| Mordred | 48/12b | | | | | Superior |
| Tristan | 49/29b | | Permian | 0.80 bcm | May 1976 | Mobil (60%) |
| Tristan NW | 49/29 | | | | | Granby |
Note: bcm = billion cubic metres, bcf = billion cubic feet

## Developments

The fields were developed with an array of platforms and subsea completions. Production from the fields was principally routed via existing infrastructure to the onshore Bacton gas terminal.
Arthurian fields offshore installations :
| Field | Water depth, metres | Field installations | Export to | Export pipeline, length and diameter (inches) | Production started | Decommissioned | Current or last operator |
| Arthur | 42 | 3 Subsea wells | Thames 49/28A | 18.2 miles, 12” | 2005 | 2014 | Esso |
| Avalon (developed as Windermere) | 35 | Fixed steel | Markham | 6.8 km, 8" | April 1997 | April 2016 | Ineos |
| Camelot North | 15 | Fixed steel CA | Leman 27A | 9 miles, 12” | October 1989 | 2011 | ERT, Perenco |
| Camelot Central South | 15 | Fixed steel CA | Leman 27A | 9 miles, 12” | October 1989 | 2011 | Perenco |
| Camelot North East | 43 | Fixed steel CB | Camelot CA | 1 mile, 6” | December 1992 | 2002 (reused) | |
| Excalibur | 27 | Fixed steel EA | Lancelot | 5 miles, 12” | October 1989 | 2017 | Perenco |
| Galahad | 20 | Fixed steel monotower | Lancelot | 16 km | November 1995 | Operational | Perenco, Chieftan, Premier Pict |
| Gawain | 37 | Subsea | Thames 49/28A | 9.6 miles, 12” | October 1986 | 2014 | Perenco |
| Guinevere | 17 | Fixed steel | Lancelot | 4 miles, 8” | June 1993 | Yes | Perenco |
| Lancelot | 21 | Fixed steel | Bacton | 40 miles, 20” (LAPS) | June 1993 | Operational | Perenco |
| Malory | 21 | Fixed Steel | Tee on Galahad -Lancelot pipeline | 10” | October 1998 | Operational | Perenco |
| Mordred | 20 | Subsea well | Galahad | | | | |
| Tristan | 37 | Subsea drilled from Welland | Welland & Thames | | Nov 1992 | 2014 | Silverstone |
| Tristan NW | | Subsea well | Davy | 15.5 km, 6” | 2008 | 2010 | Granby, Silverstone |
The pipeline from Lancelot to Bacton is known as the LAPS pipeline (Lancelot Area Pipeline System).
The Lancelot installation also provided an export route for gas from the Durango and Waveney fields.
| Field | Waveney | Durango |
| Block | 48/17c | 48/21 |
| Installation | Fixed steel platform | Subsea wellhead |
| Water depth, metres | 23 | |
| Operator | ARCO then Perenco | Bridge North Sea Ltd |
| Reservoir | Rotliegend | Rotliegend |
| Gas reserves, billion cubic feet | 84 | |
| Production start | 1998 | 2008 |
| Export to | Lancelot | Waveney |
| Pipeline, length and size | 7.65 km, 10-inch | 14.7 km, 6-inch |
| Pipeline number | PL1639 | PL2555 |

## Production

The peak and cumulative production of gas from the Arthurian fields was as follows.
Arthurian fields peak and cumulative gas production :
| Field | Peak production, bcm per year | Peak year | Cumulative production to 2014, million cubic metres (mcm) |
| Arthur | 0.858 | 2005 | 2,378 |
| Camelot North | 0.20 | 1990 | 921 |
| Camelot Central South | 0.60 | 1990 | 6,015 |
| Camelot North East | 0.10 | 1993 | 498 |
| Excalibur | 0.53 | 1994 | 6,449 |
| Galahad | 0.707 | 1997 | 4,579 |
| Gawain | 0.929 | 1996 | 6,311 |
| Guinevere | 0.27 | 1994 | 2,728 |
| Lancelot | 0.93 | 1993 | 8,640 |
| Malory | 0.668 | 1999 | 4,045 |
| Tristan | 0.20 | 1992 | 1,062 |
| Tristan NW | 0.026 | 2008 | 45 |
| Windermere (formerly Avalon) | 0.438 | 1998 | 2,112 |
The gas production profile from Camelot Central South (in mcm) was as follows:
The gas production profile from Lancelot (in mcm) up to 2014 was as follows:
The gas production profile from Excalibur (in mcm) up to 2014 was as follows:
The gas production profile from Gawain (in mcm) up to 2014 was as follows: