Spread moored FPSO (Floating Production and Storage Off-loading) vessels are typically used in the large West African oil fields. The oil from these vessels is transferred to shuttle tankers via an Oil Loading Terminal(OLT). This usually consists of 2 to 3 flexible offloading lines installed between the FPSO and a Single Point Mooring (SPM) with large internal diameter for 24 hour offloading. The final connection between the SPM and the shuttle tanker is made by floating hoses.Currently the flexible off-loading lines (OOL) are designed with steel wire armor, as typically used in the Offshore West Africa Fields. With pipes reaching 23Љ internal diameter and up to 2300m in length, the steel wires give the pipes a substantial weight generating the need for a large number of buoyancy modules to minimize the tension at the FPSO and OLT. These modules significantly add to both the cost and the installation time.Carbon Fiber Composite (CFC) is characterized by its light weight and exceptional fatigue performance, with the ability to be manufactured as an armor wire in a long continuous single length (more than 4000 meters). It can be used as an alternative to steel wire armors to design an optimized flexible pipe structure with significant advantages:• 45% decrease in submerged weight • Potential to install in double catenary configuration, without leading to excessive top tension • Buoyancy Modules are no longer required -installation is safer and quicker • Riser configuration is no longer impacted by fluid density These advantages allow greater flexibility in the position of the FPSO relative to the SPM with a fixed length of riser. Because CFC Armor is not susceptible to corrosion, service life of the flexible pipe is unaffected by breaching of the outer sheath and subsequent flooding of the annulus.This new design of flexible pipe, together with the installation and operational configurations, will be presented in this paper. In order to demonstrate the suitability of CFC, the material performance testing in severe fatigue and ageing conditions will be disclosed. The economic viability will be demonstrated by showing how the material cost is offset by the elimination of buoyancy modules and faster installation. Additionally this technology enables flexible OOL risers to be produced in a long single length.

Spread moored FPSO (Floating Production and Storage Offloading) vessels are generally used for the large West African oil fields. The oil is transferred from the FPSO to shuttle tankers via an Oil Loading Terminal (OLT). 2 to 3 large diameter flexible lines are connecting the FPSO to the OLT. The final connection between the OLT and the shuttle tanker is made by floating hoses. The single length of each flexible pipe can be typically 2,300 meters or higher, and the internal diameter is generally very large in the order of 15_23″ to minimize the pressure drop and the offloading time. Conventional flexible pipe is the most suitable solution for this application. However, its long length and large diameter require a large number of buoyancy modules which are necessary to support the substantial weight generated by the steel armor wires. An alternative to steel is Carbon Fiber Composite (CFC). This material is not only twice as strong and five times lighter than a high strength steel but it is also characterized by its exceptional performance in fatigue. As the weight of the composite armor flexible pipe is significantly reduced, the use of buoyancy is no longer necessary. The pipe can also be manufactured in a single length without intermediate connection. A qualification program based on a 19″ internal diameter prototype has been launched. This is the first time that a large internal prototype with Carbon Fiber Composite Armor (CFA) and end-fittings have been designed and manufactured. The main goals are to confirm the suitability of the CFA flexible pipe for oil offloading application in accordance with the design tools. The mechanical behavior responses of the CFA are monitored by strain gages when the flexible pipe is in straight and curved positions under internal pressure and bending cycles. The paper will present the main mechanical properties and the overall performance of the flexible pipe designed and tested. The economic viability will be demonstrated by showing how the CFC material cost is positively offset by the removal of the buoyancy modules and a faster offshore installation.

Since the early 2000’s singing risers phenomenon has been encountered. The so called Flow Induced Pulsations (FLIP) phenomenon occurs in dry gas risers (such as Gas Export lines) and may generate high tonal noises up to 110 dB but may also lead to high vibration of adjacent equipment leading to significant fatigue failure. This publication presents the recently developed model that aims at performing FLIP assessment for rough bore gas flexible pipes. The developed model provides the FLIP onset velocity and frequency for a given rough bore. It will also describe the main contributing factors such as the inner layer corrugation profile, the operating conditions (pressure, temperature and flow rate) and adjacent equipment’s acoustic reflection contributions. In addition, a Flow Induced Pulsation test carried out in 2003 to 2006 will be presented. Test outcomes will be compared to model presented in the first part. Finally, reliability of the model will be presented detailing benchmark with past tests and FLIP experienced on fields. To conclude, the model enables predictions and recommendations to avoid FLIP at an early stage prior to project execution.

Large gas field developments are an important trend of the oil and gas industry and is likely to be reinforced in the next decades. For these developments, flexible pipes with larger Inner Diameter (ID) and high flow rates are more and more required. This paper presents solutions developed to improve flow assurance in gas flexible pipes by assessing and removing flow induced pulsations (FLIP) risk occurrence and optimizing the maximum allowable flow rate. This trend leads the industry to have a kind interest in FLIP free flowlines and risers as well as in flexible pipes with improved flow rates capacities for equivalent diameters. Beginning of the 2000’s smooth bore gas export flexible riser was a pioneered FLIP free solution which is now a well-known, field proven and recognized technology. In addition, the market and industry trend have led to develop a full panel of solutions to answer new market requirements: FLIP and pressure losses methodologies, appropriate selection of conventional carcass and smooth bore flexible pipes (smooth carcass & plastic smooth bore). This paper describes the different solutions to enhance the flow assurance of flexible pipes for gas applications (less pressure losses & FLIP proof) with different flexible pipes solutions. Then a focus is done on the development of a cost-effective solution applicable to all types of pipes: the smooth carcass. This new carcass is an incremental improvement of existing technology. The industrialization, prototype manufacturing, qualification program and technical performances obtained so far including FLIP aspect, pressure loss and global mechanical behavior are detailed. Results have demonstrated that the smooth carcass allows reducing the pressure losses compared to flexible pipe with standard carcasses and thus to optimize the fluids flow rates or to reduce the flexible pipe internal diameters. Complete API 17J qualification compliance is planned for end 2018 for both static and dynamic applications. Specific dedicated competencies and technologies were developed to answer market requirements of the new gas field developments. Furthermore, the development of smooth carcass will tackle the singing phenomenon on gas flexible lines, and provide an optimized solution for flow assurance improvement to oil and gas operators.

Flexible pipe is a cost-effective and tailor made pipeline solution. Nevertheless, today's demanding market conditions call for new solutions with further increased cost effectiveness to satisfy demand for a reliable and very economical solution. The paper will focus on a new qualified solution whereby the interlocked pressure shaped armour wire is replaced by single strip made of carbon steel wound on the pipe with 50% overlapping. A large percentage of the market is dominated by smaller diameter (<12″) pipe for low pressure, static flowline/jumper applications in shallow water, such solution will typically cover such domain range. In this paper will be covered the profile description and associated qualification tests, as well as the cost effectiveness and economic viability. Currently, flexible pipes are suitable for a wide range of technical specifications, including inner diameters (ID) from 2″ up to 21″ ID, design pressure up 20,000psi, temperature up to 150°C and water depths to 3,000m. Such pipes are made of an interlocked pressure armour wire (shaped wires), resulting in relatively high inertia pipe, with added weight leading to manufacturing challenges and associated cost. This new pressure armour strip profile was developed and qualified with the following outcomes: Reliable qualification of a technology from 4″ to 12″ ID following API RP 17B process.Significant cost reduction compared to current design in similar cases when this new technology is applied.Simple and cost effective installation feasibility facilitated by weight optimisation and associated top tension reduction (horizontal over boarding of the flexible pipe over a gutter using a tensioner or use of low tension vertical pipelay systems). The new pressure armour strip profile (profiling of the strip) was engineering detailed, a reliable qualification program was conducted on 6″ flexible pipe following API RP 17B process. Such qualification program implies pipe characterization against: crushing, bending, internal pressure, burst limit, and deviated tension. Finally, cost impact assessment was conducted. Some additional benefits associated with this innovative design include the elimination of pressure armour unlocking phenomenon during service or installation and reduced gas diffusion into the annulus.