KASSEL, Germany – Subsea 7’s Seven Arctic vessel has installed the flexible risers at Wintershall Dea’s Nova field in the Norwegian North Sea.
They are now ready to connect the underwater pipelines to the Neptune Energy-operated Gjøa platform. Most of the Nova subsea hardware is now in place, according to Wintershall Dea.
The risers tie two production pipelines, as well as a water injection and a gas lift pipeline, to the specially constructed Nova module that was installed on the host platform Gjøa in May 2020. Through the risers, Gjøa will provide injection water and lift gas to the Nova field and receive the hydrocarbon well stream.
National Oilwell Varco designed and fabricated the risers in Kalundborg, Denmark. After the summer the risers will be tied-in to the pipelines, tested, and finalized for commissioning and production start.
As part of the riser installation, the Gjøa platform was shut down for two weeks, allowing the new subsea hardware to be connected to the Nova topsides module. The operation was supported by Rosenberg Worley, which was also conducting other work on the Nova topsides aboard Gjøa.
The installation was planned to coincide with a general shutdown of the St Fergus onshore terminal, to make it cost effective, the company said.
Nova, 17 km (10.6 mi) southwest of the Gjøa platform, in a water depth of 370 m (1,214 ft), is under development via two subsea templates. Production is expected to start next year. Oil from Nova will be transported from Gjøa through the Troll Oil Pipeline II to Mongstad, associated gas will be exported via the Far North Liquids and Associated Gas System pipeline to St Fergus in the UK.
Dennis L. Dickhausen, Wintershall Dea Nova Facilities Vice President, said: “The riser installation is a big milestone for the subsea part of the Nova development. It is the last piece of the puzzle in completing the subsea pipeline systems. With all the pipelines and risers now in place, we are nearing finalization of the Nova subsea scope. The next step will be to start drilling.”
Wintershall Dea is the operator and has a 45% stake in the Nova project. The other partners are Spirit Energy Norge AS (20%), Edison Norge AS (15%), Sval Energi AS (10%), and ONE-Dyas Norge AS (10%).
When Nova comes onstream, it will be Wintershall Dea’s fourth operated subsea field in production in Norway.