Laggan

Location

The Laggan and Tormore fields are situated approximately 125 kilometers north-west of the Shetland Islands in the UK. They are located in blocks 206/1a and 205/5a, respectively, at a water depth of 600 meters (1,968 feet).

Ownership and Operation

The fields are owned by Total E&P UK (60%), SSE E&P UK (20%), and Dong E&P (UK) (20%). Total E&P UK is the operator of the project. However, as of recent updates, the field participation has changed, with ownership now held by INEOS, Kistos, TotalEnergies, and Viaro Energy.

Discovery and Licensing

• The Laggan field was discovered in 1986 and licensed to Total in 1995.
• The Tormore field was discovered in 2007, with the discovery well recording a test flow rate of 32 million cubic feet of gas per day and condensate of 75 barrels per 1 million cubic feet of gas.

Reserves

The total field reserves are estimated to exceed one trillion cubic feet of gas and condensates, which is approximately 230 million barrels of oil equivalent.

Production

• The two fields together are expected to produce around 90,000 barrels of oil equivalent per day (boe/d) at peak production.
• The daily production includes 14 million cubic meters of gas and condensate.
• Production from the fields began in February 2016, with peak production achieved in the same year.

Field Development

• The fields were developed using a fully subsea to shore development scheme, with no offshore surface platforms.
• The development involves a long subsea tie-back to the Shetland Gas Plant (SGP) at Sullom Voe, which is about 100 kilometers from the fields.
• The SGP processes the gas and condensate before exporting the gas to the Frigg UK Gas Pipeline System and then to the FUKA St Fergus Gas Processing Terminal on the East Scottish Coast.

Subsea Infrastructure

• The subsea infrastructure includes eight subsea wells and two subsea production systems (one for Laggan and one for Tormore).
• Each production system comprises two six-slot production manifold templates.
• The fields are connected to the SGP via dual 143 km, 18-inch diameter multi-phase flowlines.
• Additional fields, such as Glenlivet and Edradour, are also tied back to the SGP using similar infrastructure.

Drilling and Construction

• Appraisal drilling on the Laggan field was completed in 2004, and on Tormore between 2008 and 2010.
• Development drilling was carried out in two phases, starting in 2012, with the West Phoenix semi-submersible rig operated by Seadrill used for offshore drilling.
• Major contractors involved included FMC (subsea control and production systems), Allseas (pipelines), Subsea7 (subsea lines and umbilicals), Petrofac (SGP construction), and others.

Economic and Employment Impact

• The project required an estimated £2.5 billion ($3.8 billion) investment, with Dong contributing about £500 million.
• The project created 800 jobs during construction and employs 70 personnel during operations.

Production Lifecycle

• The fields have an estimated production life span of approximately 20 years, with production expected to continue until the field reaches its economic limit in 2054, based on current economic assumptions.

Infrastructure for Third-Party Access

• The Greater Laggan Area facilities are designed to accommodate gas from third-party fields, with provisions for tie-in points across the manifolds, spare capacity in the umbilicals, and hot-tap connections to the multiphase pipelines.

Environmental and Technological Significance

• This project is the first fully subsea to shore development in UK waters, marking a significant technological advancement in the recovery of gas from deep and harsh environments.
• It has opened up the West of Shetland area for further gas exploration and development, contributing to the UK's energy security and its transition away from coal to less carbon-intensive energy sources.