Åsgard

First in the world

Project description:

• The Åsgard field is at the Haltenbank some 200 km west of Nord-Trøndelag. This is where the world’s first DEH project was installed for Statoil in year 2000.
• At Åsgard, there are six pipelines heated by DEH and tied back to the floating platform. Nexans supplied all DEH-specific equipment, from the platform to the end of the pipeline.
• The project was the first of its kind following a long development phase in partnership with Statoil and SINTEF. 

Challenges of the project:

• Mechanical loads: Trawling and pipe movements create large mechanical loads on the cable. The Piggyback Cable which lies along the pipeline cannot have mechanical protection in the form of metallic armouring because this reduces the efficiency of the DEH System.
• Insulation: High operating temperatures meant new challenges in terms of the insulation system’s lifetime.
• Installation: The DEH cables and equipment must be installed at the same time as the pipeline. 

Nexans' solution:  The world’s first dynamic DEH riser and the largest cable by diameter and weight per metre at time of installation: Dynamic DEH Riser Cable with four power cores each of 12 kV with 1600 mm2 copper conductor and hydraulic tubes. The world's first coupling between high voltage cable and pipeline on the sea bed. Long-term studies and qualification work with Statoil and SINTEF resulted in a successful and eco-friendly design. Built-in trawl protection on the piggyback cables (patented solutions).