Subsea Umbilicals 

The current trend among offshore oil & gas industries is a move towards extensive use of Subsea Production Systems (SPS) to develop new Deepwater fields. In the same time, new developments based on subsea processing systems lead to an increasing requirement of power supply, e.g. 2-4MW, 15kV.

These production systems are typically remotely operated from an adjacent manned installation or from shore via umbilical which provide the following functions:

Umbilical are structures that contain two or more functional elements, i.e. thermoplastic hoses and/or metal tubes, electrical cables and optical fibres. These are typically assembled together with a helical technique, to form a circular bundle, which is then encased in an extruded thermoplastic sheath, reinforced with two or more contra-helically applied layers of steel wires and finished with a second extruded thermoplastic sheath.

Many offshore projects require the consideration of greater depths, longer umbilical and more control functions than those common in the past. Further, most oil companies are striving to reduce the time required to complete such developments, i.e. fast track projects. As a result, the selection of umbilical has become more critical as many factors such as performance, fluid compatibility, impact on interfaces, ease of deployment, etc. must be considered during the selection process.

This document aims at providing valuable information to help the design engineer in the selection of the most suitable umbilical, knowing that a detailed analysis during the engineering phase is essential to ensure that all of a specific project’s unique features and needs are fully addressed.

Since umbilical performance is a function of material, size, length and other parameters, Chapters 2 and 3 give an overview of available umbilical technology and the associated topside and subsea interface requirements.

As electro-hydraulic control systems are widely used in Deepwater applications and require a high level of umbilical reliability and tube cleanliness, the test requirements from the reception of core components in the manufacturing facility to the umbilical installation in the field are presented in Chapter 4.

Chapter 5 is dedicated to the description of some typical umbilical configurations found in deep water applications including installation methods / sequences and laying equipment. Virtually all production control system applications are based on the use of either thermoplastic hose or metal tube.

The limitations of these fluid lines are described in Chapter 6.

The presentation of advantages and disadvantages of different types of umbilical is addressed in Chapter 7.

Finally presentation of issues regarding Deepwater steel tube umbilical will conclude this document in Chapter 8.

Tip Click these links below for access to 3D resources: 3D Interactive Model of Umbilical Structures 3D Pictures of umbilicals

This study is based on the following sources:

Reference is made to the documents "Subsea Connections & Tie-in Methods" Ref.[30], "Riser Systems" Ref.[24] and "Subsea Processing and Pumping Systems" Ref.[34], parts of the Deepwater Reference Book documentation.

We wish to thank the manufacturers and subsea contractors for the provision with courtesy of technical information and photographs of their products.