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.

Despite very attractive properties, aerogels have been limited to specialist industrial applications due to complex and expensive production procedures. Aspen Aerogels Inc. have developed a revolutionary process of fabrication that significantly reduces production time and costs. Aspen Aerogels Inc. have also developed a fibre reinforced flexible blanket aerogel. Aerogels can also be produced under several alternate forms to fit a wide range of industry applications at competitive costs. Aspen Aerogels Inc. and Technip have collaborated on the development of a flexible aerogel blanket for the insulation of a reelable pipe-in-pipe that can meet the lowest overall heat transfer coefficient (OHTC) requirements without a significant increase in overall size and costs. A qualification programme has been carried out to demonstrate the integrity and thermal performance of the aerogel blanket during the pipe-in-pipe fabrication, reel-lay and service life. The successful results of these qualification tests are presented along with a design example demonstrating the thermal performance of the system. Introduction The emerging trend for the development of deepwater and ultra deepwater offshore fields is a requirement for flowline and risers with very high insulating performance in order to minimize the risks of hydrates or wax formation. Technip have already a significant track record of design, construction and reel installation of pipe-in-pipes (PiP), which can meet the insulation requirements. Figures 1 and 2 show the evolution of the OHTC and water depth specifications of PiP installed by Technip of future PiP for contracts awarded to Technip where engineering is in progress. A clear trend towards lower OHTC (below the 1 W/m2K mark) and greater water depths (in excess of 1,000 m) can be seen. The aerogel based system produced by Aspen Aerogels Inc. combines the qualities that allow Technip to design a cost effective, lighter reelable PiP with higher insulating performance. The system is now qualified for reeling and offshore operation. Aerogel Material Aerogels were first produced by Klister in 1931. His original aim was to demonstrate that a light solid structure existed within a liquid gel. After several attempts, he managed to extract the liquid phase out of the solid structure, without collapsing it. The new product, called aerogel, gathered a range of attractive physical properties such as very low thermal conductivity, high temperature resistance, good mechanical properties combined with very light weight, sound proofing and high impact energy absorption capabilities. Aerogels owe their qualities to their structure. It consists of a network of molecular chains, which can be organic or silica based, see Figure 3. Aerogel product is a "micoporous material" having a tridimensional nano-strucutre with pores sizes smaller and more "coherent" than the well known microporous based on fumed or pyrogenated silica used or proposed for years in many industries including offshore pipelines [1]. There are three forms of heat transfer mediums through any porous material, which are conduction, convection and radiation. The long molecular chain generates a very long and tortuous conduction path for heat transfer. The heat exchange due to gas convection is minimized because of the small size of the material pores.

There is an increasing demand for submarine pipelines which can transport highly corrosive products. Due to the significant cost of solid stainless steel pipes, the interest in more economical mechanically lined pipes (i.e. carbon steel pipes lined with a thin stainless steel layer) is growing. There is further incentive to combine this technology with the highly efficient reel-lay method, which is an alternative to the S-lay and J-lay methods for installation of small to medium size steel submarine pipelines. Reeled pipelines, however, are subjected to at least two symmetrical plastic strain cycles during installation. The plastic straining associated with reeled installation may trigger wrinkling of the corrosion resistant liner. Technip have undertaken a development programme in accordance with DNV-RP-A203 to design and qualify mechanically lined pipes for reeling without the use of internal pressure. The proposed novel design enables a safe and reliable reeled installation and a subsequent lifetime operation of mechanically lined pipes by controlling the liner thickness.

There is an increasing need for transport of corrosive constituents in the subsea oil and gas sector, which generates a high demand for corrosion resistant alloys. Stainless steel, such as duplex, is routinely used for subsea pipelines. Clad pipe with a thin CRA layer metallurgically bonded to a carbon steel pipe is also widely applied, especially for high temperature pipelines and SCRs as it does not suffer from significant strength reduction at high temperature and has an excellent fatigue performance in sour environment. The interest has grown in lined pipe, which combines the benefits of clad pipe with more attractive procurement costs and shorter lead times. Here, CRA and carbon steel are adhered by means of an interference fit. The authors have patented and qualified a lined pipe design, which enables safe reeled installation without internal overpressure. To extend the field of applications of lined pipe, large scale bending and fatigue tests have been carried out in this work. It has been confirmed that the novel reeled lined pipe is suitable for SCR service.

The reel-lay method is a fast and cost efficient alternative to the S-lay and J-lay installation methods for steel pipelines up to 20″ in diameter. The quality of the pipeline construction is high due to onshore welding under controlled conditions. However, reeled pipelines are subject to plastic straining (up to approx. 2.3%) during installation. It is therefore common practice to specify a minimum required wall thickness to avoid on-reel buckling. For a given pipe outside diameter and bending radius, formulae developed for pipes under pure bending are generally used. In addition, to ensure the integrity of pipelines during reeling, a minimum spooling-on tension is specified and tolerances on pipe properties, such as wall thickness and yield strength, are constrained. Tolerance limits are specified to reduce the likelihood of spooling two consecutive pipe joints, which have a significant difference in plastic moment capacity (mismatch). It has been shown previously that high levels of mismatch can trigger an on-reel buckle [1]. The reliability of the reeling process is indeed related to the uniformity of pipe properties. It can therefore be supposed that more uniform pipe properties may allow reeling of thinner-walled pipes, while achieving the same level of reliability. This issue has been investigated as part of a wider evaluation of reeling mechanics and the development of procedures for optimized assessment of the process, including such aspects as the effect of the geometry of pipelay equipment [2]. This paper explores methods that can be used to evaluate the reliability of reeling a given pipe onto a given vessel. Particular focus is given on the selection of appropriate material variation parameter for the assessment. The concept of an averaging factor is introduced as a means to relate variations in individual wall thickness and yield strength measurements to the variation in pipeline cross-section, which determines the likelihood of buckling. It is suggested that, in the future, this factor could be used as a method for optimizing design for reeling when using higher quality pipe.