Strategy Concerning Composite Flowlines, Risers and Pipework in Offshore Applications
Authors: Loureiro Junior Walter Carrara , dos Santos Junior Fernando Costa , Henriques Carlos Cunha Dias , Meniconi Luiz Claudio de Marco 
Published: May 2013

Composite materials can offer technologically viable and cost effective solutions for the production of highly corrosive fluids in very deep water. On the other hand, there is a need to access the key issues of durability and integrity assurance of the components made from composite materials in these very demanding operational environments. Research on this area seeks to address their safe use along the whole operating life of the production systems. This paper gives a general overview of ongoing research activities on the subject of offshore utilization of composites flowlines, risers and topsides piping. New possible applications are also briefly described. The company philosophy and the main drives of this research area are presented. The research projects that are currently in progress or are yet intentions, with traditional suppliers and newcomers are also briefly described. Focus is given in the development of non-metallic dynamic risers both bonded and unbonded and the benefits of their use for the production of corrosive fluids like the ones found in Brazilian Pre-salt fields. Petrobras views about riser configurations prone to take advantage of composite materials properties are given. An internal research on the development of a metal composite interface (MCI) for a hybrid catenary riser pipe is also presented. Finally, the developments concerning integrity assessment of glass reinforced polymer (GRP) piping for offshore production plants are presented and discussed.

Introduction

There is no need to spend much time in explaining the advantages of composite pipes for offshore operations as the high strength, light weight, corrosion resistance and good fatigue behavior of these materials are well known. The problems lie in two areas clearly identified: the long term behavior and the availability of trusted inspection methods. Much was achieved on these areas in recent times, and this is one of the reasons why the interest in composites for offshore operations raised again.

Petrobras has participated on composite riser research initiatives since their early beginnings. It was one of the sponsors of the composite drilling riser Joint Industry Project (JIP) of Vetco Grey and The University of Houston, started in 1995. Then, that research was continued through the CompRiser JIP that run from 1996 and 2001, involving AkerKvaerner, Conoco, EU Thermie, Chevron, Hydro, Statoil, Shell and Petrobras (1). There was a plan to deploy an instrumented composite drilling riser joint in different positions along a drilling riser operating in a given platform. The idea was to submit the composite joint to different load levels - dependant on the position of the joint alongside the riser - and by doing that to address and its structural behavior in a real operational environment.

In the meantime, Petrobras also followed and focused on the development of composite wires for tensile armors of flexible unbonded risers. Following that and because of possible operational and inspection issues, the research on this area cooled a bit, but now, given the Pre Salt scenario with its very deeper waters and very corrosive fluids the prize to be won by adopting composite risers got even higher, which is the essential condition and driver for a technological breakthrough.

Also, the idea of using thermoplastic composite bonded pipes became a reality through studies and efforts of companies new to the offshore pipe market. Petrobras has been involved with the majority of these studies and this paper aims to provide its vision and strategy concerning this very interesting application development. Finally, given the similarity of issues involved, an internal comparative study on the fatigue behavior of composite topside piping joining systems is presented and a discussion is made about similar evaluation of their pressure surge response.