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The domestic demand of gas is increasing in Brazil. Petrobras is responding to this challenge by bringing several gas fields on stream offshore Brazil. Among them is the Canapu field, located east of the State of Espirito Santo, about 75 km off the coast, in a water depth of 1608 m. The produced gas is transported using a 20 km long pipe-in-pipe (PIP) system to the Cidade de Vitoria floating, production, storage and offloading system (FPSO) located in the Golfinho field to be processed and then exported onshore through an existing gas pipeline.Technip was awarded an engineering, procurement, construction and installation (EPCI) contract and was responsible for the detailed design and installation of the first ever reeled PIP system offshore Brazil. The project was awarded on a fasttrack basis, which required design, qualification, fabrication and installation of the PIP system in less than 18 months. The scope also included two pipeline end terminations (PLET) with seven gate valves, free span rectification, the crossing of three flexible flowlines, and, pre-commissioning activities (flooding, cleaning, gauging and hydrotesting). The PIP system was also prone to lateral buckling, which required definition of a robust mitigation strategy.The design requirements for the Canapu PIP system involved the design and qualification of several technically advanced components and novelties in PIP design including the application of the first ever reelable mechanically clamped waterstop system and the use of buoyancy modules for lateral buckling management on a PIP system. This paper presents the overview of the design, fabrication and installation of Canapu PIP system as well as a summary of the qualification test program performed for the different PIP system components.

Large diameter UOE pipes are being increasingly used for the construction of offshore pipelines. Since oil discoveries are moving towards ultra-deepwater areas, such as Pre-Salt in Brazil, collapse resistance is a key factor in the design of the pipelines. It is known that the cold forming, and the final expansion in the UOE linepipe manufacturing process, reduces the elastic limit of the steel in subsequent compression. Due to this, the DNV collapse formula includes a fabrication factor that derates by a 15% the yield strength of UOE Pipes. However, DNV also recognizes the effect of thermal treatments and the code allows for improvement of the fabrication factor when heat treatment or external cold sizing (compression) is applied, if documented. This paper presents the qualification of UOE pipes with enhanced collapse capacity focusing the use of a fabrication factor (αfab) equal to 1. TenarisConfab has performed a technology qualification process according to DNV-RP-A203 standard “Qualification Procedures for New Technology”. The main aspects of the qualification process are presented in this paper which included significant material and full scale testing, including combine load testing, and final analysis. The qualification process achieved successful results and this will allow use of a fabrication factor equal to 1 directly in deepwater and ultra-deepwater offshore pipeline projects with a possible reduction in material and offshore installation costs and also potentially enhancing the feasibility of many challenging offshore projects.

Subsea pipelines designed to operate under high pressure and high temperature (HP/HT) conditions tend to relieve their axial stress by forming buckles. Uncontrolled buckles can cause pipeline failure due to collapse, low cycle fatigue or fracture at girth welds. In order to control the lateral buckling phenomenon, a methodology was recently developed which consists of ensuring regular buckle formation along the pipeline. Distributed buoyancy is one of the most reliable initiation techniques utilized for this purpose which have been recently applied in some projects. The behavior of pipeline sections with distributed buoyancy is normally evaluated by Finite Element Analyses (FEA) even during preliminary design when analytical models could be adopted. FEA are also utilized in order to support reliability calculations applied within buckle formation problems. However, the referred analyses are usually time-consuming and require some experience to provide good results. This paper presents an analytical formulation for a pipeline section with distributed buoyancy, which can be utilized during preliminary design in order to evaluate the influence of buoyancy sections over buckle shape, feed-in length, tolerable Virtual Anchor Spacing (VAS), etc. Regarding buckle formation, this paper also presents a methodology to determine an expression for the critical buckling force to be used as part of the limit state function in reliability analyses, which combines the results obtained from the referred analytical formulation with Hobbs infinite mode.