Wintershall Dea completes subsea installation work at key Norway tie-back scheme

Wintershall Dea has completed installation of key subsea infrastructure at its Nova subsea tie-back project off Norway ahead of schedule as it has also gained safety consent to start development drilling work.

A pair of manifolds for production and water injection have now been installed by Subsea 7 onto templates on the seabed in a water depth of 370 metres at the field in the northern North Sea, as well as pipeline spools, about a month ahead of a scheduled June completion date.

The installation work was carried out by the UK-based contractor’s vessel Seven Arctic after transporting the infrastructure from a supply base at Floro in western Norway to start the subsea campaign this year.

The vessel Siem Spearfish then connected the three production spools, which had been installed using a single lift, and the injector spool to the manifolds and pipelines.

'Key miletsone' amid Covid-19

The German operator hailed it as a “key milestone” for the project to tie back the satellite field to the Neptune Energy-operated Gjoa platform amid disruption and delays to other field development schemes off Norway due to the Covid-19 pandemic.

The Petroleum & Energy Ministry recently confirmed that Martin Linge, the Njord Future redevelopment, Hyme, Bauge, all operated by Equinor, Repsol's Yme and ConocoPhillips-operated Tor will all see start-up delayed to 2021.

“Despite the challenging environment, Subsea 7 managed through careful planning and efficient delivery to finalise installation even earlier than scheduled,” Wintershall Dea’s Nova subsea manager Baard Owe Bakken said.

It follows installation last year of the two subsea templates that were fabricated by local contractor Aker Solutions at its Egersund yard in Norway, which is now facing a work slowdown due to quarantine measures and travel restrictions as a result of the pandemic that have reduced its workforce.

Aker Solutions and Subsea 7 earlier won contracts worth a total of around $230 million covering fabrication and installation of subsea facilities at Nova, which is being developed at a cost of Nkr9.9 billion ($1.3 billion), with start-up scheduled for next year.

The manifolds installed at Nova will serve as an interface between the subsea christmas trees, and the pipelines and umbilicals.

The 212-tonne production manifold will receive the Nova hydrocarbons before sending them through pipelines to Gjoa.

The 116-tonne water injection manifold will pump water from Gjoa into dedicated wells for pressure support in the reservoir. The spools connect the manifolds to the pipelines.

Rig consent granted

Meanwhile, Wintershall Dea has gained consent from the Petroleum Safety Authority to use semi-submersible rig West Mira for production drilling and completion work at the field, with an estimated duration of 388 days.

The 2019-built seventh-generation harsh-environment rig, owned by Seadrill offshoot Northern Ocean, will drill six wells under a firm contract worth $106 million, with options for 10 additional wells.

This work was originally due to start in March this year, although the operator had an option to bring this forward to the third quarter of last year that apparently did not pan out.

The firm contract is listed by Seadrill as starting in November last year with a duration to October 2021, though this could be extended to October 2022 if all the options are exercised.

Wintershall Dea holds a 45% operating stake in production licence 418 that hosts Nova, with partners Spirit Energy on 20%, Edison on 15%, and Solveig Gas unit Capricorn and One-Dyas on 10% apiece.