In 2007 JDR was contracted by Coogee Resources Pty Ltd., to supply four umbilicals, totalling more than 30 km in length and weighing more than 1000 tonnes. These vital connections that link the subsea facilities to the Montara FPSO and WHP provide for hydraulic and chemical duty, as well as 3.6 kV electric power cores and fibre optic cables.

The Montara development is located in the southern Timor Sea approximately 650 kilometres west of Darwin, in about 80 metres of water. The development also includes the Skua oil fields located around 25km to the north west, and the Swift and Swallow fields (9km to the south east of Skua).

Coogee’s choice to implement an ultra long tieback for the Montara development allows them much greater flexibility regarding final FPSO location. There was also a strong preference to use an installation vessel that would be locally available, thereby avoiding substantially higher mobilisation charges.

These factors required JDR to provide subsea umbilical joint hardware that would allow vertical reel deployment and thus achieve the extended tieback distance required by the project.

The joints were to afford the completed umbilical length a level of integrity as would be expected from the single unjointed length. The dynamic section of the FPSO umbilical is arranged in a steep wave configuration with buoyancy modules fitted to the umbilical to result in the modelled catenary shape needed. The dynamic umbilical will be subject to substantial forces including the additional forces from the FPSO itself; therefore these factors had to be taken into account during design, testing and engineering of the umbilical.

The dynamics of the project required that the lower buoyancy module be positioned only 8m above the seafloor. This necessitated a large dynamic bend restrictor at the riser base, and a subsea vertebrae bend limiter on the static side to transition to the seafloor.

The primary umbilical length of 18km is designed for vessel installation from vertical reels and includes 2 complete subsea umbilical joints. Installation of the joints involves mechanical assembly only and planned to take under 12 hours including testing.