Umbilical Technology for Arctic Projects

Abstract This paper outlines the state of the art of subsea control umbilical technology, making reference to the requirements imposed by projects in arctic environments. The mechanical demands on dynamic, riser umbilicals are dominated by the environmental loadings and motions of the host vessel. Common solutions for Arctic applications are often based on an FPSO (Floating Production Storage and Offloading Vessel) and require the umbilical to withstand significant bending and tensile loading due to relatively large vessel motions and disconnect scenarios. The linear weight of the umbilical and provision of moulded polymer bend stiffener devices are of prime importance. Flexibility, minimum bend radii and resistance to fatigue damage are defining properties in the ability to provide solutions. Other considerations relevant to Arctic environments are; temperatures, compatibility with installation methods such as trenching and on-bottom stability management by designed in weight or rock dumping etc. This paper presents solutions based on armoured thermoplastic umbilicals containing hydraulic hoses and steel tube umbilicals. The benefits and limitations of both solutions are presented and contrasted. The status of each technology is highlighted with reference to track record and previous project experience. The conclusion of this paper is that well engineered umbilical solutions are available to meet requirements with current visibility and emphasis is on the identification of any future emerging technology gaps. The effectiveness of thermoplastic umbilicals as a solution for very dynamic requirements is supported by experience gained to date and the use of thermoplastics in very low temperature applications is further supported by ongoing development work. Introduction An umbilical is defined as an assembly of fluid conduits, electrical and fibre optic cables, either on their own or with combinations of each other, cabled together for flexibility. In any offshore field development, the umbilical is a critical component for the production of hydrocarbons. In the context of this paper, the term umbilical is used to refer to permanently installed subsea applications where the umbilical can provide a combination of functions.