General Cable manufactures power cables for the world’s deepest subsea umbilical cable
Part of the Cascade & Chinook crude oil drilling project of the Petrobras company in the Gulf of Mexico
General Cable, a world leader in the cable sector, has been actively involved in the operational start-up of the world’s deepest subsea umbilical cable installation. This cable has been specially designed to supply energy to an undersea crude drilling system at a depth of 2,700 metres, the deepest of such installations to date. The project, by the oil company Petrobras, goes by the name of Cascade & Chinook, in reference to the two drilling rigs in the Gulf of Mexico, hundreds of miles from the coast of Houston (United States).
The project has required General Cable’s Manlleu plant (Barcelona) to work for three years on the design and manufacture of power cables, the first of their kind in the world because of the conditions under which they will eventually be installed and operate. The project specifically entails 260 km of RHE-2OL 12/20 kV 1X150 k mm2 H16 type cable, designed by the plant’s R+D+i department. These power cables are arranged in groups of three cables inside a final umbilical cable, manufactured by Aker Solutions and composed of three groups of power cables, plus other structural elements.
Tests of hyperbaric pressure, traction and axial compression
To win the project, General Cable’s R+D+i department spent a year working on the design of several prototypes and had to pass a long pre-qualification process. The performance of different tests was required, including the hyperbaric pressure test to ensure that the cables would withstand the enormous pressure exerted at 2,700 metres below the ocean surface. Tests of traction, axial compression, and tensile and compression tests of mechanical yield, previously never performed by a cable manufacturer, were carried out to ensure proper cable performance during installation and useful life, with consideration for the fact that part of the installation would be dynamic.
Early January this year saw initial shipments of the project’s first manufactured and inspector-approved reels to the port of Barcelona. Eventually, after seven months’ work, the 37 reels have all been sent to the United States, where the umbilical cables of the Petrobras project are now being manufactured at the production plant of the company Aker Solutions in Alabama. Special installation conditions at sea have made it necessary for the oil company to design a specific safety system, which is activated if hurricanes are forecast. In this event, the FPSO vessel (a ship for loading and transporting crude) holding the umbilical cables and the rest of the installation is uncoupled from the installation and floats dynamically on the sea.
A project that opens the way for a new method of drilling for crude
Although this is not the first umbilical cable project to have been undertaken at the Manlleu plant, it has nonetheless been rather special both because of its duration and the way in which the client has monitored manufacture and been in contact with the General Cable team on a daily basis. The Cascade & Chinook project is now a true benchmark for hundreds of manufacturers of cables, platforms and oilrigs. If this initial phase is successful, it will open up the way for a new method of drilling for crude at great depths.