Gjøa, Norway
The turnkey solution comprised the longest HVAC submarine cable in the world at this time installed in one complete length and at this voltage.
- References
- Gjøa, Norway
Key Facts
Scope
- Power-from-shore HVAC cable system, including 96.5 km of static submarine XLPE cable and 1.5 km of dynamic submarine XLPE cable.
- Project management.
- Cable system design, engineering and manufacturing.
- Installation of cable, cable joints and transition joints.
- Testing and commissioning.
The project
Gjøa was the world’s first floating oil and gas platform to be powered from the onshore grid.
Gjøa is a large development project in the North Sea. The production at the field began in 2010 via a semi-submersible platform located off the Norwegian coast. The floating production facility is owned and operated by ENGIE E&P.
Oil and gas platforms typically use gas turbines to generate the electric power needed for their operations. Gas turbines consume large volumes of gas that could otherwise be sold and produce large quantities of CO2 (carbon dioxide) emissions. They have significant and costly space and weight requirements and require regular maintenance.
ENGIE E&P has therefore decided to prioritize the use of emission-free hydropower from the Norwegian grid to power offshore production facilities. It is a smart way of reducing the cost and the environmental footprint of its operations.
At the time of this project, the powering of a floating platform with electricity from the onshore grid had never been attempted as there was not yet any AC cable sufficiently robust to withstand the mechanical stress of floating applications.
ENGIE E&P turned to us for an innovative power cable system solution for Gjøa, based on prior successful partnership projects within power-fromshore solutions in the North Sea.
The solution
The pioneering 115 kV HVAC cable system is designed, manufactured and installed to withstand the extreme conditions and transmit 40 MW of power for decades to come.
The Gjøa floating production facility is located 360 meters above the seabed. The cabling consists of static HVAC cable system along the seafloor for a distance of 96.5 km and the world´s first 1.5 km dynamic cable, which links the static cable to the floating platform.
Although the platform is moored to the seafloor, it can be moved as much as 75 meters to one side by the wind and the waves. Working closely with ENGIE E&P, the solution is developed to handle the substantial mechanical stress and risk of fatigue, with an operating life of at least 35 years. An important feature of the dynamic design is the replacement of the conventional lead sheath, which is not sufficiently robust for this application, with a new innovative sheath.
The turnkey solution at this time comprised the longest HVAC submarine cable in the world installed in one complete length and at this voltage. It opened up a new era for the offshore oil and gas industry by enabling a floating production facility to be powered entirely from onshore.
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