Flow assurance is among the main design issues for the development of deepwater fields. The hydrocarbon product must be transported from a remote well up to the topsides, without experiencing significant heat losses to the environment. In addition to high 'steady state' insulating performance, the system muat also provide good transient cool down behaviour to prevent the formation of wax or hydrate during shut down and to minimise the time required to resume production.A number of solutions have emerged to address these challenges. These are high performance passive insulation, dual insulated lines allowing a pigging loop, extended cool down pipeline concepts based on phase change materials and active pipeline heating. This paper compares the practicality, performance and cost of these generic concepts on the basis of some typical field development scenarios. It also presents a range of pipeline products developed and qualified by Technip on the basis of these concepts.

In the design of flexible pipelines for offshore field developments, the determination of the pipe resistance while subjected to external pressure and bending is very important in deepwater and is now required by the ISO and API standards. One of the critical failure modes being associated with this type of loads is the hydrostatic collapse. The collapse value of flexible pipe is calculated with a model validated with over 200 tests performed on all possible pipe constructions. This model has an analytical basis, and has been established in the past, leading to a fast and straightforward use. In order to address the bent collapse failure mode, Technip and IFP have therefore developed and improved over the past few years an analytical calculation model, based on the collapse model for straight pipes. The purpose of this paper is to present this design methodology and its validation. The modelling principles of the collapse calculation of straight flexible pipes are firstly presented, along with the main hypotheses. The adaptation to the case of curved pipes is detailed in the sequel of the paper. Many types of flexible pipe samples have been tested up to collapse both in straight and curved configurations. The results of these tests have been used to validate this model. In the paper, several tests results will be presented and compared with the calculations. This model is effective, of straightforward use, and has been certified by a third party. It allows Technip to optimize the flexible pipe design in particular for ultra-deep water applications, where external pressure resistance is very important.

The paper is relevant to riser technology and specifically, qualification of flexible pipes for water depths up to 3,000m.This paper describes a comprehensive program aimed at the qualification of flexible pipes for ultradeep water applications. The primary design driver for ultradeep water flexible pipe applications is the resistance to hydrostatic pressure, in combination with dynamic curvature cycling. The two associated critical failure modes are hydrostatic collapse and lateral buckling of armour wires.Technip have developed dedicated flexible pipe components to address the severe loading conditions encountered in water depths up to 3,000m. Hydrostatic collapse resistance has been addressed by a thick inner carcass layer and a PSI pressure vault. Armour wire lateral buckling, which is induced by axial compression in the armour wires in combination with dynamic curvature cycling, has been addressed by the design and industrialization of new tensile armour wires.The design qualification process for these improvements was completed on two levels. Initially, a large number of pipes were subjected to dynamic cycling testing under high hydrostatic pressure in a hyperbaric chamber so as to determine design limits in terms of pipe diameter, water depth and component sizing. Then, design combinations were selected for testing in a real deepwater environment in the Gulf of Mexico. This second level of tests referred as Deep Immersion Performance (DIP) tests aimed at validating the results obtained from hyperbaric chamber tests. The DIP tests replicated the actual design conditions to which a flexible pipe would be subjected during installation and operation.The development of new and modified flexible pipe components provided a suite of flexible pipe designs suitable for extended water depth application. The final phase of the qualification program, namely the DIP tests, was completed in 2010. It provided design limitations of the new designs for both 9" and 11" internal diameter flexible pipes, in sweet and sour service in water depths up to 3,000mThis paper clearly demonstrates the suitability of flexible pipes as a valid solution for ultradeep water applications as long as the mechanical behavior of the pipe components is adequately addressed.

This paper presents the latest progress on the armor wires lateral buckling phenomena with the qualification of flexible pipes for water depths up to 3,000m. The design challenges specific to ultra deep water are governed by the effect of the external pressure: Armor wires lateral buckling is one of the failure modes that needs to be addressed when the flexible pipe is empty and subject to dynamic curvature cycling. As a first step, the lateral buckling mechanism is described and driving parameters are discussed. Then, the program objective is presented together with flexible pipe designs: - Subsea dynamic Jumpers applications; - Sweet and Sour Service; - Internal diameters up to 11″. Dedicated flexible pipe components were selected to address the severe loading conditions encountered in water depths up to 3,000m. Hydrostatic collapse resistance was addressed by a thick inner carcass layer and a PSI pressure vault. Armor wires lateral buckling was addressed by the design and industrialization of new tensile armor wires. The pipe samples were manufactured using industrial production process in the factories in France and Brazil. The available testing protocols are then presented discussing their advantages and drawbacks. For this campaign, a combination of Deep Immersion Performances (DIP) tests and tests in hyperbaric chambers was selected. The DIP test campaign was performed End 2009 beginning 2010 in the Gulf of Mexico using one of Technip Installation Vessel. These tests replicated the actual design conditions to which a flexible pipe would be subjected during installation and operation. The results clearly demonstrated the suitability of flexible pipes as a valid solution for ultra deep water applications. In addition, the DIP tests results were compared to the tests in hyperbaric chambers giving consistent results. This campaign provided design limitations of the new designs for both 9″ and 11″ internal diameter flexible pipes, in sweet and sour service in water depths up to 3,000m.

The development of Ultra Deep Water (UDW) oil and gas fields, down to 3000 m and beyond, requires high specification flowline and riser systems. At these depths, the flexible pipes must withstand high axial loads and severe dynamic loadings generated by currents, waves and vessel motions. Moreover, the constraints generated by the dynamic loadings are often combined to corrosion issues linked to the presence of CO2 and H2S. In case of sour service application, the structural layers of a classical flexible pipe require the use of steel with reduced mechanical properties compared to a sweet service application. The combination of UDW and sour service applications consequently lead to a riser design of considerable top tension. The main challenges of such applications are the suspended weight and the fatigue / corrosion performances. Carbon fiber composite have demonstrated high specific strength and outstanding corrosion and fatigue damage resistance. The use of carbon fiber composite instead of conventional steel for the tensile armour layers of flexible pipes represents a great alternative for the development of UDW applications combined with sour service conditions. Technip has been engaged for a number of years in the development and qualification program of Carbon Fiber Composite (CFC) Armour. In 2011, an important step has been passed with the successful realization of a full-scale tension-flexion dynamic test. The program of the full-scale dynamic test is based on a representative Brazilian offshore project, a typical UDW application. The CFC prototype structure was designed considering a 9” gas export riser installed at a water depth of 2140m, in free hanging configuration. The riser is made of 2 parts: a top riser with CFC armours and a bottom riser with steel armours. 1.8 millions of cycles were performed without damage, combining internal pressure, tensile loading and bending cycling. The whole test was monitored by acoustic emission to detect the potential damage of the CFC armours. After explaining the advantages of CFC structures compared to traditional steel structures, the paper will focus on the realization of the full-scale dynamic test program. It will detail the design and manufacture of the prototype structure, the construction of the test program representative of the offshore conditions first and then extended to more severe loadings. The paper will also present fatigue analysis and the construction of the CFC fatigue curves.