Résumé -Risers de forage en offshore profond et technologies associées -L'IFP a développé des outils et des technologies répondant aux attentes des contracteurs de forage qui veulent forer en offshore profond, dans des conditions d'environnement sévères avec des densités de boue élevées. La métho-dologie proposée vise à optimiser le dimensionnement des risers de forage en proposant des règles pratiques de design et un logiciel approprié. Pour réduire les temps morts en opération, un connecteur de riser de forage, le Clip Riser, a été développé. Il permet la connexion rapide des joints de riser. Cette technologie est unique car elle ne comporte aucun écrou ni filetage et ne requiert pas de précontrainte dans le connecteur lors de l'assemblage. Pour réduire la masse des équipements sur les bateaux de forage ainsi que la tension en tête du riser, l'IFP a mis au point une technologie appelée « tubes frettés » (tubes acier/composite). Ces tubes frettés pourront être utilisés pour remplacer les lignes de sécurité du riser de grand diamètre (kill and choke lines -φ 114,3 mm) par des lignes deux fois plus légères.Afin d'améliorer le comportement axial du riser, l'intégration hyperstatique des lignes de sécurité a été envisagée. Cette intégration consiste à solidariser les lignes aux extrémités de chaque connecteur si bien qu'elles participent à la résistance axiale du riser. Les avantages de ce système seront présentés dans cet article. Finalement, toutes ces technologies et tous ces outils devront répondre aux attentes des contracteurs de forage et permettre ainsi de repousser les limites des risers à des profondeurs plus grandes et des conditions opérationnelles plus sévères.Mots-clés : riser, forage, offshore profond, dimensionnement. Abstract -Ultra Deep Water Drilling Riser Design and Relative Technology -IFP has developed tools and technology to answer the waiting of contractors that wish to drill in deeper water

The main purpose of this paper is to present the technology of hybrid tubes developed to reduce the mass of auxiliary lines of drilling risers used in ultra deep water, by replacing conventional choke and kill lines with lighter tubes. They are composed of a steel core hoop wound with a strip made of carbon fibers impregnated with a polyamide thermoplastic resin.The paper describes the structure of hybrid tubes, the design methodology and the manufacturing process. It presents all the tests carried out to qualify the technology and the conditions of the field test in preparation aboard a drillship offshore Angola. The principle of their integration in riser joints is described. Finally, the architecture of drilling risers including hybrid tubes is commented and their technical benefits are discussed.In conclusion, studies performed at IFP prove that hybrid tubes reduce the weight of auxiliary lines by 50% and that this technology is well suited for ultra deep drilling risers.

With the current increase in water depth requirements for offshore drilling, the drilling riser has to overcome more and more severe issues regarding its weight and size. Its architectural optimization is therefore a great challenge for the future developments, especially for the upgrade of small rigs, since the necessary increase in buoyancy will be limited by maximum outside diameter considerations. In order to reduce the riser weight, the hybrid pipe technology, which consists in winding composite material under tension around a metallic core, has been developed to lighten the choke & kill lines. The technology and its advantages were already presented elsewhere [1,2] and the present paper deals with further results of qualification, through field and laboratory testing of C&K lines. In particular, numerous damages (shock, notch, punching) were created on different specimens to assess their influence on the resistance under internal pressure. As a further step in the qualification, three hybrid C&K lines were field tested on the Pride Angola drillship, to evaluate the technology under real drilling conditions. After the field test, the hybrid pipes were analyzed and burst tests were performed to estimate the potential influence of handling and ageing. This paper recalls the basis of the technology and describes the different laboratory tests. It finally details the phases of the field test and comments burst tests. The different results are very encouraging regarding the technology itself and show how some issues related to the assembly of the peripheral lines on the riser joint can be improved. Introduction The global trend of increase of oil prices has led the companies to increase their effort for E&P in new deep offshore fields. However, this trend is hindered by the saturation of the offer of the drilling rigs, increasing their daily cost. Therefore, within the next years, new drilling rigs will enter in service, but also upgrades of old ones. The drilling riser, which can be seen as the submerged part of the wells, is one of the crucial equipment of these new built and upgrade projects. This riser lying on the deck represents a lot of space and weight. In use, it undergoes very high pressure, tension and bending stresses. The increase in water depth requirements has led the current riser technologies close to their limits. This is the reason for developing new technologies that could be applied either on new rigs or for the upgrade of existing rigs. Conventional low pressure drilling risers are equipped with peripheral safety lines to control and kill the well in case of blow out. The standard full steel Choke & Kill lines, having to withstand high pressure in use, require a great wall thickness and consequently a high weight. In order to reduce this weight which may represent one third of the riser mass, IFP and its partners have developed a hybrid technology combining steel and composite material for 4 ½" ID × 15 ksi Choke & Kill lines. This technology allows a weight reduction of approximately 50 % for the lines.