Europe Design Construction Support Execution

Baltic Pipe Project

The Baltic Pipe Project is a strategic gas infrastructure project to provide a new gas supply corridor in the European market, using a 275 km long 36” pipeline. Baltic Pipe enables the transmission of gas from Norway to the Danish and Polish markets, as well as to customers in neighbouring countries. At the same time, the Baltic Pipe will enable the supply of gas from Poland to the Danish market. SEA supported the FEED, detailed design, engineering optimisation, procurement and construction phases from Copenhagen, Warsaw and Perth.

THE CHALLENGE

As a project of strategic importance with numerous stakeholders, the pipeline design was to be achieved within a narrow set of constraints and provide assurance for the subsequent construction phase.

The region comes with a legacy of unexploded ordinance (UxOs) from WWI and WWII, including potential encounters with a range of conventional and chemical warfare munitions. Design, survey and construction planning activities must take due account of the potential impact of UxO discovery.

With a complex seabed, including boulder fields and very soft clays, existing subsea assets to cross and a complex high-traffic shipping environment, the project team faced a range of challenges that each had the potential to interrupt delivery.

Linepipe fabricated and coated in Germany, with transport to Scotland for the addition of concrete weight coat before being returned to Germany for mobilisation.

Microtunneling selected for shore crossings in Denmark and Poland following technical and schedule risk evaluation against HDD and Direct Pipe alternatives. Design finalised at 2m internal diameter and lengths of 600m and 1km, with a grouted annulus across the waterline.

Significant seabed interventions, with extended shallow water sections and numerous boulder fields. Over 50km of pre-lay trenching with backfill required, and approximately 1000 critical boulders identified and relocated. 300,000 tonnes of rock used for crossing supports, stability and lateral buckling berms, in addition to pre- and post-lay span supports.

Key Milestones

High-Value Engineering Optimisation and Construction Support

Engineering Optimisation

Following earlier support phases across FEED, detailed design and tendering, the Engineering Optimisation phase was completed entirely from SEA Global’s Perth office. Optimisation of the protection design was performed, along with on-bottom stability, spanning and lateral buckling. Significant CAPEX and schedule savings were achieved.

Staged Pipelay Sequencing

Four initiation and laydown locations identified to segment pipelay into sequenced stages. Saipem Casterone completed two sections of 35-50m water depth using triple joints, at a rate of nearly 6km / day.

Shallow Water Pipelay

Saipem vessel Castoro Sei completed the shore pull and above water tie-in in Poland, while the C10 completed the shore pull-in and second above water tie-in in Denmark.

As-built acceptance engineering

At each installation phase, the as-built surveys were sent to the SEA Global Perth office for analysis and acceptance using the automated ICE Platform workflows set up for the project. In the majority of cases, results are returned to the project within 24 hours – enabling construction activities to progress on schedule.

Commissioning and Completion

Cleaning, hydrotest, dewatering and drying operations were completed prior to connection to the onshore pipeline network in July 2022.

OUTCOME

SEA provided valuable guidance through the design and procurement phases of the Baltic Pipe project, to ensure successful completion of tendering processes and help the project team achieve a technically compliant and commercially competitive outcome.

Uniquely positioned as advisors to both design and procurement, the SEA Global specialist engineering team were able to identify a value improvement opportunity to optimise elements of the design that caused an outsize impact to the scope of seabed intervention works. This process leveraged insights from installation engineering experience and automated engineering workflows to examine the behaviour of the restrained pipeline when subject to the combined effects of temperature and pressure.

Finally, during the construction program, SEA’s ICE Platform was in constant use to monitor construction progress, update and re-run analysis models and ultimately provide comprehensive assurance that construction works had achieved a technically compliant and successful result.