The fruits of 42 million man hours of labour are starting to be reaped with the first gas from Total’s Laggan-Tormore field now having been exported from Shetland Gas Plant to St Fergus, outside Peterhead.
The first export gas headed south on Wednesday night three days after the plant took its first gas from the fields on Sunday. Shetland Gas Plant is the connecting node between the two 18-inch pipelines from the fields approximately 140km north west of Shetland and the Shetland Islands Regional Gas Export System (Sirge) which connects with the Frigg UK Pipeline (Fuka).
The two 142km pipelines, which form a complete loop, is believed to be the second longest “tieback” in the world while the plant itself is the biggest single UK construction project since the London Olympics.
The quality of the Laggan-Tormore product is high – not far short of what is required for the national gas grid. While most of the high-methane content gas will head south via the pipeline, a liquid fraction, high-value condensate, is piped next door to Sullom Voe Oil Terminal. The first condensate was also exported to the oil terminal on Wednesday.
When it is in full production, which ought to be in the next few months, the plant will produce 14.2m cubic metres of gas daily and 14,000 barrels of liquid condensate.
The entire system’s topsides and subsea operation can be monitored and controlled from a control room in Shetland Gas Plant, which is intended to be connected by video link to the oil giant’s Aberdeen headquarters.
In order to keep the gas flowing in the cold temperatures of the seabed, monoethylene glycol (MEG) is pumped offshore via an eight-inch pipeline and is injected into the liquid/gas mix at the wellheads.
A good deal of the plant is devoted to recovering the MEG, dewatering, desalting it and treating it for re-use. Another good chunk of the massive infrastructure is devoted to cleaning up the water that comes ashore in the mix, or is otherwise collected in the plant before it is pumped to sea.
With groundworks and tidying up of the site ongoing there are still around 400 people on site, with around 80 or 90 of them Shetland based, though this figure will likely reduce before he end of the year.
When the plant is in normal production around 80 staff ought to be onsite with a lesser number on the nightshift.
Costing some 3.5 billion, the plant is a hugely complex long-term project that is expected to produce a return over its 20-year life during which gas and oil prices will inevitably fluctuate.
There will be a more extensive report on Shetland Gas Plant in next week’s Shetland Times.