The Greater Laggan Area
The Greater Laggan Area consists of four producing subsea fields (Laggan, Tormore, Glenlivet and Edradour) that are tied back to the Shetland Gas Plant (SGP) at Sullom Voe on the Shetland Islands via a long-distance 143 km flowline system.
Identical template manifolds are installed on both the Laggan and Tormore fields (6 slot) and the Glenlivet and Edradour fields (4 slot), with the template concept driven by a need for high reliability in the harsh weather environment. These manifolds tie-in to dual 143km 18” diameter multi-phase flowlines that deliver hydrocarbons to the SGP. The Tormore manifold sits at the far extremity of the pipeline with Laggan 16km further downstream. The Glenlivet and Edradour manifolds tie-in to the main flowline via 35km and 17km 12" flowlines respectively.
Production is commingled and processed through the SGP. Production from the subsea fields is measured by multiphase flow meters. Discrete metering packages report production streams before custody transfer of condensate to the Enquest operated Sullom Voe Terminal for processing and re-delivery; and gas for export into the FUKA Pipeline System via the Shetland Island Regional Gas Export System (SIRGE System).
First gas from Laggan and Tormore was achieved in 2016, with the follow-on Edradour and Glenlivet fields brought onstream in 2017.
Provisions for Third Party Access
The Greater Laggan Area facilities form a major infrastructure development intended to export “stranded” gas from the West of Shetland region to the National Grid gas entry point at St Fergus. In order to accomplish this ambition, the Greater Laggan Area facilities are designed to accommodate gas from 3rd parties wishing to enter the system for transportation and/or processing. The key elements of this design philosophy are as follows:
- Tie-in points available across the Greater Laggan Area manifolds.
- Spare capacity in the umbilical to add additional satellite developments.
- Hot-tap Ts for tie-in to the multiphase pipelines between Laggan and SGP (3 on each flowline and the MEG pipeline).
- Capability to operate the multiphase pipelines in LP and HP modes.
- Space at the SGP to add extra process units in order to increase capacity.