New Technology FSRU Mooring Now Operational

The PGN FSRU Lampung project offshore Indonesia reached an important milestone last month when the unit, along with its associated mooring and pipeline to shore commenced commercial operation. The system is the largest and most complex FSRU project Höegh LNG has undertaken so far and includes a new tower yoke mooring system that is a first in the FSRU world.

This type of mooring has previously been used in oil fields where the oil comes up from the sea floor for processing and transport. In the FSRU context, operations are reversed and the mooring takes regasified LNG from the FSRU down to the sea floor for transport to shore via the pipeline.

The mooring system is designed by SOFEC in Houston and built by Penglai Jutal Offshore Engineering Heavy Industries in China. While FSRUs are considered a big investment, this one cost around $300m, the mooring system is also a complex, high specification structure. In this case it cost around $100m.

Although its location is out of cyclone range, this single point mooring system has been designed to withstand earthquakes with four feet on the sea floor and ‘toes’ that extend through the hollow feet 50m into the seabed. 

Power and control systems are all managed from the FSRU. Topside, the system includes a yoke for mooring the FSRU directly to a fixed tower. A turntable is fastened to the tower with a roller bearing to allow the 170,000cbm FSRU, and any LNG shuttle tanker delivering LNG to it, to freely weathervane about the tower. The mooring has pitch and roll joints and includes a large ballast tank filled with water to provide the necessary restoring force to minimize vessel motions. Two mooring links suspend the tank from a support structure mounted on the vessel.

For Birgitte Hjertum, vice president of strategy, the project has been a great success, but she is leaving her options open for future projects. “Since all FSRU projects differ with respect to both environment, metocean data and water depth, and the customers’ technical and operational requirements, we need to tailor-make and optimize the technical solution for each project. If we conclude that the tower yoke mooring system is optimal for another FSRU project we will definitively use this mooring system again. Going forward, I believe it will be easier for other FSRU providers/project developers to use this solution now that it is proven for LNG as well.”

The PGN Lampung FSRU and mooring system has now entered its final commissioning phase.