An umbilical is an assembly of fluid conduits (thermoplastic hoses and steel tubes), cables (electrical and fibre optic), and power cores, joined together for flexibility and over-sheathed, with or without armouring, for mechanical strength and stability. The emphasis of this paper is on the global configuration design and analysis of offshore umbilicals. The extreme and interference analysis methodologies are presented. One example is given for the application of very small OD electrical umbilical in shallow water in West Africa. The proposed global configurations are presented. Another example is presented for the application of a hydraulic umbilical in deep water in the Gulf of Mexico. The selection of the global umbilical configuration in deep water depends on the host vessel. In other words, the vessel motion characteristics may dominate the umbilical configuration selection for the deep water application. This paper also deals with the influence of the bottom current on the global design of the umbilical in deep water. It can be concluded that an optimized umbilical global configuration, which meets the strength and interference design criteria, can be achieved for the application of a small OD electrical umbilical in shallow water in West Africa as well as for a steel tube designed hydraulic umbilical in deep water in the Gulf of Mexico.

As the offshore industry looks beyond water depths of 3,000 ft for future oil and gas production, the industry standard steel catenary spread mooring (CSM) system used on all floating production systems installed to date becomes increasingly inefficient and costly, An alternative to the CSM is the Taut Leg Spread Mooring (TLSM) system with its characteristic short scope legs and vertically loaded anchors. In water depths greater than 3,000 ft, it has been shown that TLSMS comprised of synthetic mooring lines have performance advantages over systems utilizing steel wire rope and demonstrated potential for significant cost reductions. Early studies investigated the use of aramid fiber rope due to its high strength, lower in-water weight and lower axial stiffness as compared to ropes made from steel. Later studies indicated that the material properties of polyester fiber, primarily it's lower Young's modulus, made polyester mooring lines more suitable for use in TLSMS2'S. As the TLSM knowledge base expanded, aramid rope construction evolved. Earlier efforts to match the characteristics of steel wire rope have given way to new generation 'soft' aramid constructions. This paper compares the mooring performance and total installed cost of a "soft? aram id TLSM to a typical polyester configuration. Both systems were designed for use in the Gulf of Mexico (GOM) with an FPS based on the Aker P45. Introduction This study was performed with the objective of investigating and comparing two taut leg spread mooring systems comprised of differing types of synthetic rope. The two types of synthetic mooring line constructions investigated were:Whitehill 36-strand aramid rope.Marlow Superline parallel-strand polyester rope. Mooring systems using both constructions were designed for the new-build Aker F'45 Semi-submersible Drilling and Production platform (FDPU), The first P45 is currently being constructed for Norsk Hydro for their Njord field development. The vessel's displacement will be 49,600 tons when completed; production facilities will be capable of 70,000 BOPD of crude throughput. The particulars of the Aker P45 are presented in the Appendix to this document. The study this paper is based upon has been planned and organized such that it would be a suitable extension to work previously presented13 A deep water (3,000 ft) GOM location was chosen as the field location for this work. Three environmental design scenarios were investigated for this site. They are:Maximum Wave Hurricane Event with associated wind and currentMaximum Loop Current Event with associated wave and windMaximum Wave Case -5 year return The Maximum Wave Hurricane condition noted above was the controlling case and, therefore, was used in the design effort. The goal of this study is to evaluate whether mooring lines constructed of aramid fiber are cost and performance competitive with polyester for deep water taut leg spread moorings. As part of the scope of the study, installation costs and schedules have been developed for each system. Preliminary component specifications were developed to a level of detail where costs could be estimated for each mooring case.

This paper discusses work conducted during the design, procurement and installation of Enserch Exploration, Inc.'s Garden Banks 388 FPF mooring system. The design began with the execution of a trade-off study evaluating and comparing previously installed floating production moorings in the Gulf of Mexico, coupled with evaluation of new concepts and emphasis on cost effective solutions. The results of this effort led to considerable cost savings for Enserch, compared to conventional FPF mooring systems previously installed in the Gulf of Mexico.