Tailoring the Local Design of Deep Water Composite Risers to Minimise Structural Weight

Abstract

Following the rising technological advancements on composite marine structures, there is a corresponding surge in the demand for its deployment as ocean engineering applications. The push for exploration activities in deep waters necessitates the need for composite marine structures to reduce structural payload and lessen weights/loads on platform decks. This gain is achieved by its high strength–stiffness modulus and light-in-weight attributes, enabling easier marine/offshore operations. Thus, the development of composite marine risers considers critical composite characteristics to optimize marine risers’ design. Hence, an in-depth study on composite production risers (CPR) is quite pertinent in applying composite materials to deep water applications. Two riser sections of 3 m and 5 m were investigated under a 2030 m water depth environment to minimise structural weight. ANSYS Composites ACP was utilized for the CPR’s finite element model (FEM) under different load conditions. The choice of the material, the fibre orientation, and the lay-up configurations utilised in the modelling technique have been reported. In addition, the behaviour of the composite risers’ layers under four loadings has been investigated under marine conditions. Recommendations were made for the composite tubular structure. Results on stresses and weight savings were obtained from different composite riser configurations. The recommended composite riser design that showed the best performance is AS4/PEEK utilising PEEK liner, however more work is suggested using global design loadings on the CPR.

Review of Composite Marine Risers for Deep-Water Applications: Design, Development and Mechanics

“…Comparisons based on the mechanical, chemical and physical properties of composites against steel and wood have shown that composites to have excellent behaviour in coastal environments, as opposed to mild steel [295][296][297][298][299][300]. To evaluate the strength of marine risers, effective tension profiles are usually used [11,[24][25][26][27]98,[137][138][139][140][141][142][149][150][151][152][153]. Details of similar effective tension profiles on marine hose risers are available in earlier studies [48][49][50][51][52][53].…”

“…Presently, the scale tends to shift more towards small-scale methods. The tests conducted include failure tests, fatigue, collapse and burst pressures [148][149][150][151][152]. There are limitations to fullscale testing, as can be seen in the size of composite risers as shown in Figure 19.…”

“…Numerical analysis on composite risers is critical for ensuring the validity and accuracy of the chosen discretisation by examining its properties [140][141][142][143][144][148][149][150][151]331]. There have been a number of investigations on composite risers, including nonlinear failure analysis, mechanics and fatigue due to compression, tension, bending, torsions and their combined loading, internal fluid pressure and sea water hydrostatic pressure, as tabulated in Table 7.…”

“…This has also led to advances in the use of TCP pipes on composite risers and related marine composite tubulars for water injection, transport, product transfer and loading and fluid discharge services [31,51,150]. Based on numerical models presented on different CPR models of well-validated composite risers with safety profiles from results of the stress analysis, conducted in ANSYS APDL [137][138][139][140][141][142] and ANSYS ACP [143][144][145][146][149][150][151][152], respectively. Additionally, both researchers used different platforms-while the former used a TLP (tension leg platform), the later used a SPAR (single-point anchor reservoir) and a PCSemi (paired-column semisubmersible).…”

Review on Fixed and Floating Offshore Structures. Part II: Sustainable Design Approaches and Project Management

“…In addition, there are supporting attachments for these offshore installations that are used for a variety of functions and in a variety of water depths and environments globally. These components included drilling/production marine risers [17][18][19][20][21][22][23], composite risers [24][25][26][27][28][29][30], mooring lines [31][32][33][34][35][36][37][38][39], and marine hoses [40][41][42][43][44][45][46][47][48][49]. Figure 1 depicts some offshore platform installations.…”