Norway: Nova risers successfully installed
Wintershall Dea has completed another major milestone for the Nova project. The risers for the operated field in the Norwegian North Sea are successfully installed. 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.
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 newly installed risers, Gjøa will provide injection water and lift gas to the Nova field and receive the hydrocarbon well stream.
With the field’s two underwater templates and manifolds in place, the pipeline systems installed and modifications to Gjøa well underway, Wintershall Dea now looks toward the start of the Nova drilling campaign.
“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”, said Dennis L. Dickhausen, Wintershall Dea Nova Facilities Vice President.
National Oilwell Varco designed and fabricated the risers in Kalundborg, Denmark. They were picked up by Subsea 7’s Seven Arctic vessel which installed them on the Nova field, 120 kilometres northwest of Bergen. 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 topside module. The operation was supported by Rosenberg Worley, which was also conducting other critical work on the Nova topside aboard Gjøa. The installation was carefully planned to coincide with a general shutdown of the St Fergus onshore terminal, to make it cost effective.
Bård Owe Bakken, Nova Subsea Manager, said: “Despite the challenges we encountered related to COVID-19, we managed to install the risers safely and within the planned time frame. This is thanks to excellent planning and dedication of everyone involved, and One Team collaboration between Subsea 7, Rosenberg Worley, Neptune Energy and Wintershall Dea”.
Nova is located about 120 kilometres northwest of Bergen and approximately 17 kilometres southwest of the Gjøa platform in the Norwegian North Sea. Wintershall Dea has a 28% interest in the Gjøa license.
Partnership: Wintershall Dea (operator 45%), Spirit Energy Norge AS (20%), Edison Norge AS (15%), Sval Energi AS (10%) and ONE-Dyas Norge AS (10%).
Water depth: 370 metres
Development solution: Nova is being developed as a subsea tieback connecting two templates to the existing Gjøa platform which is operated by Neptune Energy. Gjøa will receive the production fluids and provide injection water and lift gas to the Nova field. 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 (FLAGS) pipeline to St Fergus in the UK, supplying the European energy market.
The use of existing infrastructure enables a cost-efficient extraction of the resources in the reservoir at 2,570 metres below sea level and extends the economic lifetime of the existing infrastructure.
About the risers
The flexible risers are a connection between the Nova topside module on Gjøa, and the pipelines on the seabed. The production risers transport Nova hydrocarbons from the wells and through the pipelines at the seabed up to the sea surface, to the topside module on the platform. The water injection and gas lift risers supply injection water and lift gas from the topside module down to the pipelines at the seabed and into the Nova wells.
When Nova comes on stream, it will be Wintershall Dea’s fourth operated subsea field in production in Norway.