Next Generation Umbilicals for Electrification of Offshore Installations

Increased focus is given to environmentally friendly solutions in exploration and production of petroleum. For Norway, in particular electrification of the continental shelf is a political target. For the industry, main focus is improved recovery rate, wh ich leads to more subsea infrastructure that requires electrical power. Power is also applied in electrical heating of flowlines which is an environmentally friendly alternative for flow assurance. In addition power cables are used in offshore windfarms One step towards increased electrification offshore is to solve thermic challenges for power cables and umbilicals. Power umbilical consists of functional elements for power and control, as steel tubes, electrical cable and optical fibres, in addition t o power conductors. Aker Solutions? umbilicals have a unique proprietary design using thermoplastic profiles to space the functional elements. However, a major challenge for all umbilicals is low heat conductivity in the polymer materials causing reduc ed power transmission capacity, leading to larger electrical cables with high costs as a consequence to avoid over heating. Over heating due to poor heat dissipation can over time cause stress cracking of insulation around individual functional elements. The idea is to use a combination of nano-sized fillers and new architecture modifying profiles with a target to increase the thermal conductivity by one order of magnitude. This can only be reached by using filler materials with high aspect ratio and e xtremely high thermal conductivity, such as carbon nanotubes or graphene. Exotic filler materials alone will not give the anticipated improvements, as they will alter mechanical properties and interact with antioxidants in the polymer material potenti ally shortening service life time. Detailed focus on polymer and filler materials to achieve the targets without compromising other requirements, as well as safe handling of nano-sized materials throughout the production of umbilicals, is needed. Reaching our targets will be a major step forward towards electrification of offshore installations, utilization of offshore wind power, electrical heating of flowlines and electricity to subsea power units. As part of the material development process the promising material compositions also had to proove proper extrudability with stable results. In this part of the project serious challenges were met. Poor results both in thermal conductivity and mechanical properties of initial samples resulted in the need for further material development and failure mode investigation. This affected both the schedule and the economy of the project and it was necessary to change focus from verification of a demo-umbilical to completion of a material composition that could proove both proper extrudability and required thermal and mechanical properties. By desember 2015 a promising and representative test profile was finally achieved.

For Norway and other oil&gas producing countries reductions in CO2 emissions related to exploration and production of petroleum products is increasingly focused. For Norway in particular electrification of the continental shelf is a political target also supported by environmental organizations. One important part of the challenge reaching these goals is related to today?s technical solutions regarding power cables and in particular the complex multi purpose umbilicals. The connections between onshore and offshore installations or between several offshore installations are made with umbilicals. There are several designs on the market. Aker Solutions is in the forefront of deep-water, high-pressure umbilical technology. Aker Solutions' umbilicals today ha ve a unique proprietary design with recognized advantages. A major challenge for all umbilicals is low heat conductivity in polymer materials causing reduced power transmission capacity, the need for thicker electrical cables, high weight and more expensi ve installations to avoid over heating. Our idea is to use a combination of nano-fillers and new architecture modifying the umbilicals in such a way that thermal conductivity will be substantially improved. Our target is to increase thermal conductivity by one order of magnitude, a very challenging task that only can be reached by using filler materials with high aspect ratio and extremely high thermal conductivity. Exotic filler materials alone will not give the anticipated improvements as there are se veral challenges to overcome. Research and development is needed with detailed focus on the polymer and filler materials to achieve the targets without compromising other requirements, including safe handling of nano-sized materials throughout the product ion of the umbilicals. Reaching our targets will be a major step forward toward electrification of offshore installations and utilization of offshore wind power, it will also give huge commercial benefits.