Arran Gas and Condensate Field

The Arran gas and condensate field located in the North Sea, UK, came on stream in September 2021.

Shell UK, the operator, holds 44.57% stake in the Arran field, while the other partners are RockRose Energy (30.43%) and ONE-Dyas (25%). Shell UK assumed operatorship of the Arran field from Dana Petroleum in October 2018.

The project partners reached a final investment decision (FID) on the £300m ($382m) offshore gas and condensate field development in the same month.

The Arran field has been developed as a subsea tieback to the Shell UK-operated Shearwater gas hub in the UK North Sea.

The field is expected to reach a peak production capacity of 21,000 barrels of oil equivalent a day (boed) that will include 100 million cubic feet (Mcf) of gas and 4,000 barrels of condensate a day.

Arran field location and reservoir details

The Arran gas and condensate field is located in blocks 23/11a, 23/16b and 23/16c in the Central North Sea, approximately 240km off the coast of Aberdeen, Scotland, UK. The water depth in the field area is approximately 85m.

Shell had discovered the offshore field by drilling the 23/11-1 well in 1985. The field’s reservoir consists of upper and lower Forties sandstones located between 2,400m and 2,800m beneath the seabed.

The Arran field is estimated to hold up to 30 million barrels of oil equivalent (Mboe) in reserves.

Arran field development details

The Arran field comprises four production wells drilled via two subsea drill centres, namely Arran North and Arran South, two tie-in manifold structures, and the associated subsea infrastructure.

The wellstream is transported to the Shearwater A platform via a 60km-long pipeline connected to the existing Scoter riser. An umbilical has also been laid from the Arran field to the Shearwater platform.

The Arran wellstream is processed at the Shearwater C platform. Gas is exported via the Fulmar Gas Line (FGL) to the St. Fergus gas terminal, Scotland, while condensate is transported through the Forties pipeline system (FPS).

Shearwater gas hub details

The Shearwater offshore gas hub comprises the normally manned Shearwater C integrated process, utilities and quarters (PUQ) platform and the Shearwater A wellhead platform. The two platforms are connected by an 80m-long bridge.

The Shearwater gas field, which is also operated by Shell UK, lies in block 22/30 in the Central North Sea, approximately 225km off the coast of Aberdeen. It commenced production in 2000.

Apart from handling the production from Shearwater A wells, the Shearwater C platform also processes wellstream from the Starling and Fram fields. Shell started gas production from the Starling and Fram fields in January 2008 and September 2020, respectively.

The Columbus field being developed by Serica Energy in the UK North Sea will also be tied back to the Shearwater platform.

Contractors involved in the Arran gas condensate field development

Subsea 7 was awarded an engineering, procurement, construction and installation (EPCI) contract worth up to £152.4m ($200m) for the Arran gas field development in March 2019.

The contractual scope includes project management and EPCI of 60km of mechanically lined pipe-in-pipe production flowline, as well as subsea structures and tie-ins at the Arran and Columbus gas condensate fields and the Shearwater platform.

Subsea 7 used its pipelay vessel Seven Borealis to carry out installation works on the Arran field.

Diamond Offshore Drilling’s semi-submersible drilling rig Ocean Endeavor was deployed for drilling the development wells in the Arran field.