Atlas Copco Rental UK Commences Its Largest Single Offshore Project a report by Atlas Copco Rental
Dundee, Scotland, late May 2011. Atlas Copco Rental was commissioned to commence an in-house test run and feasibility overview involving 25,000 scfm of primary air, nitrogen membranes and boosters. This comprehensive engineered rental package involved up to 22 high-pressure compressors, five nitrogen membrane units, four compressor boosters and two 500 kVA gensets, along with ancillaries and engineered peripherals.
The task was in preparation for a project to dewater and pig an 80 km long, 26 inch diameter subsea gas pipeline in the Norwegian offshore sector, where the work would be carried out from a dedicated support vessel.
With successful completion of the onshore trials, and all risk assessments complete, the packed air spread was approved by Subsea 7 and prepared for shipment.
On target to commence production of gas and oil in the latter half of 2011, the Norwegian BP Skarv project is thought to be one of BP and its partner’s most northerly offshore developments. Comprising a subsea system of 16 wells on five templates, the new development will feed gas to an 80-kilometre (50-mile) subsea spur line. This will link into Norway’s existing Aasgard pipeline, with the gas making its way to consumers in Germany.
The lead role in the process was undertaken by offshore test specialists IKM Testing of Norway.
A key part of the dewatering and drying process is to drive a train of six dewatering pigs through the pipe and it is here where
Precise pressure and flow control is vital, any fluctuations being liable to impact upon the speed and efficacy of the pig train.
The first challenge for Atlas Copco Rental, however, was to assemble all the equipment required to meet the demands of the project in the short lead time required by the client.
Over a period of six weeks, equipment was sourced from key Atlas Copco Rental outlets throughout Europe and Asia, with the
The first challenge for Atlas Copco Rental was to assemble all the equipment required to meet the demands of the project in the short lead time required by the client.
complete equipment spread assembled and readied for dry-land testing in Dundee, Scotland. Once everything was checked and tested over a multiple hour ‘simulated running’, the 400-ton equipment spread was later decommissioned and loaded onto the cargo/transit ship which was berthed in Dundee awaiting load out (see Figure 1).
From the outset, everyone's object and key priority was SAFETY FIRST.
The customers’ representatives were on-site for over eight days whilst the simulation and function tests took place at Atlas Copco Rental.
The Norwegian BP Skarv project is thought to be one of BP and its partner’s most northerly offshore developments.
Atlas Copco Rental Oil & Gas has been called in, our remit being to provide sufficient air/nitrogen volume pressure and quantity to drive the pig train through the pipeline, whilst meeting the site additional criteria.
Inert nitrogen was selected to propel the pig train through this gas line, primarily as it is a safer process and is proven to assist in the pipeline drying process.
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This maintained effective communication and ensured expectations at every stage were achieved by all stakeholders.
Finally, after successful completion and recording of the spread’s performance, the customer signed acceptance documentation and the mobilisation to site was initiated.
Fast forward to June, and the complete equipment spread was transferred from the transit vessel to Subsea 7's specialist reel-lay vessel Seven Oceans, which was berthed in Stavanger.
After full function testing on board the vessel in Dusavik, Stavanger, the Seven Oceans started transit to the Skarv field and was rigged up and readied to supply pressurised nitrogen. Filled with treated seawater, the subsea pipeline was now ready for dewatering prior to its commissioning.
© TOUCH BRIEFINGS 2011
Subsea and Pipeline
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