Umbilicals Optimum Umbilicals System for Johan Castberg From its base in Rosyth, Scotland, Oceaneering is currently working on the umbilicals for the Equinor (formerly known as Statoil) Johan Castberg field in the Barents Sea. Not only does this project include some particularly complex umbilical designs, but it also exemplifies a major challenge that the company has sought to resolve over the past few years – how to pack as much functionality as possible into a single bundle,instead of using a number of separate and less-complex lines to carry out the same activity. Using a single umbilical is considerably more cost-effective, thus reducing installation and overall project costs. “It is this sort of project where Oceaneering expertise becomes invaluable, because, as the project’s complexity increases, it requires considerably more engineering and analysis work to design and manufacture the optimum umbilicals system,” said Joao Melo, Engineering Manage, Subsea Distribution Solutions, Oceaneering. One of the innovative features of the Oceaneering-designed umbilicals system for the Johan Castberg field is the large 2.5-in. tube that forms its central core. This steel tube, which will deliver methyl ethylene glycol (MEG) into the wellstream to prevent hydrate formation, is surrounded by all the usual arrays of electrohydraulic cables and communication lines that are common features of a typical power and control umbilical.
“We have had success in fabricating a broadly similar umbilical, also with a large-diameter steel tube, for other projects out of our manufacturing facility in Panama City, Florida, but this is the first time that such a design has been manufactured at Rosyth,” Melo said.“ Projects like this require significant design and manufacturing expertise, and this drives our industry to continue to improve the engineering capabilities and skill sets to meet these demands. This is exactly the sort of thing that
UT3 Issue 3 July 2018
differentiates umbilical suppliers in the journey from concept to delivery. Way before the manufacturing starts, we essentially have to prove to ourselves and our clients that the product will work for more than 25–30 years, maintenance free, and meet the performance that the operator requires.” Even with the advanced equipment already installed at Rosyth, Melo noted that the manufacturing of these umbilicals still has its obstacles, as umbilical manufacturers normally rely on their in-house supply chain to stock ready-manufactured steel tubes wound on reels, which are often easily integrated into their fabrication
processes. The large-bore tube at the center of the Johan Castberg umbilical design, however, will have to be welded from straight lengths of pipe. The line will be fed onto large 9.8-meter reels prior to testing and assembling with the product’s other functional elements. “We have been working with Equinor on front-end engineering design (FEED) studies for this project over the last five years or so, and thus we were in a good position when we officially won the project at the end of last year,” Melo said. “We will commence manufacturing at the end of the fourth quarter of this year, for delivery at the end of 2021, and will complete the installation soon after that.”