# South Arne oil and gas field

The South Arne (Danish: Syd Arne) field is a major crude oil and associated gas production field in the Danish sector of the central North Sea. Production of oil and gas started in 1999, and peak oil and gas was in 2000.

## The field

The characteristics of the South Arne field reservoir are as follows.
| Field | South Arne |
| Reservoir | Chalk |
| Geological age | Danian and Upper Cretaceous |
| Offshore Block | 5604/29 &30 |
| Reservoir depth | 2,800 m |
| Reservoir pressure and temperature | 434 bar and 90°C. |
| Field delineation | 93 km$^2$ |
| Reserves | Oil 12.9 million m$^3$ Gas 2.6 billion Normal m$^3$ |
| Discovered | 1969 |

## Owners and operators

The field was originally owned jointly by Hess 57.48%; DONG 34.58%; Noreco 6.56%; and Danoil 1.58%. It was operated by Hess. In 2021 Hess Denmark sold its interests in South Arne to Ineos E&P for $150 million.

## Infrastructure

The field was initially developed through a single offshore installation (SA), two further field installations (WHPE and WHPN) were commissioned in 2013. Details are summarised below.
South Arne installations :
| Name | South Arne (SA) | WHPE Wellhead platform East (SA WHPE) | WHPN Wellhead platform North (SA WHPN) |
| Coordinates | 56.07835°N 4.22886°E | 56.07823°N 4.230876°E | 56.09574°N 4.219251°E |
| Production start | 1999 | 2013 | 2013 |
| Water depth | 60 m | 60 | 60 |
| Installation | Concrete gravity base and steel lattice drilling tower | Fixed steel | Fixed steel |
| Access | Helicopter | Bridge link to South Arne | Helicopter |
| Function | Wellhead, process, accommodation (57 beds) | Wellheads | Wellheads |
| Substructure weight tonnes | 112,800 | 2,224 | 2,333 |
| Topsides weight tonnes | 8,955 | 1,932 | 1,762 |
| Number of wells | 14 oil production, 7 water injection | 12 | 6 |
| Export, liquids | To subsea oil storage then by single anchor leg mooring (SAL) to tanker | To South Arne | Pipeline Bundle to WHPE (production P/L, lift gas and water injection) |
| Export, gas | 285 km 24-inch pipeline to Nybro | To South Arne | Pipeline Bundle to WHPE (production P/L, lift gas and water injection) |
The subsea oil tank has a capacity of 87,000 m$^3$ (547,230 barrels). It is 110 m by 90 m by 18 m high. The single anchor leg mooring (SAL) is located 2 km (56.09247°N 4.25615°E) from the South Arne installation.

### Hejre tie back

There are plans to tie-in the Hejre platform into South Arne WHPE. This would be via a 30 km 10-inch or 12-inch multiphase pipeline. South Arne has sufficient capacity to process the Hejre fluids.

## Production

Production facilities comprise a single three-stage oil/gas/water separator train capable of processing 50,000 barrels of oil per day (8,065 m$^3$/day), 2 million m$^3$ of gas per day, and 100,000 barrels of water per day (16,129 m$^3$/day), The gas compression is a single four-stage train.
Production from the South Arne field is aided by water injection for pressure support. Some produced water is injected into the reservoir, the remainder is treated and discharged overboard. Injection water is treated to remove sulphate ions prior to injection.
The oil and gas production profile of the South Arne field is as shown in the tables.
South Arne annual oil production (1000 m$^3$) and gas production (million Normal m$^3$) 2013-2022 :
| Year | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | Total |
| Oil | 700 | 1,023 | 1,030 | 946 | 774 | 570 | 565 | 479 | 408 | 347 | 29,802 |
| Gas | 167 | 238 | 307 | 370 | 281 | 187 | 167 | 132 | 108 | 108 | 7,665 |
South Arne annual oil production (1000 m$^3$) and gas production (million Normal m$^3$) 1999-2012 :
| Year | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 |
| Oil | 757 | 2,558 | 2,031 | 2,313 | 2,383 | 2,257 | 2,371 | 1,869 | 1,245 | 1,139 | 1,164 | 1,066 | 1,004 | 803 |
| Gas | 167 | 713 | 774 | 681 | 544 | 461 | 485 | 366 | 234 | 225 | 271 | 248 | 238 | 194 |