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Rolf Baarholm - One of the best experts on this subject based on the ideXlab platform.
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Steel Lazy Wave Riser Configuration for Turret Moored FPSO With Disconnectable Turret in Deepwater
Volume 5B: Pipeline and Riser Technology, 2015Co-Authors: Daniel N. Karunakaran, Sankar Subramanian, Rolf BaarholmAbstract:Recently turret-Moored FPSOs have been used in many deep water developments worldwide, with consideration of disconnectable turrets for harsh environment applications. This trend makes the interactions between FPSO and Risers system more important. Further, Steel Lazy Wave Risers (SLWR), which is a compliant variant of the mostly commonly used Steel Catenary Risers (SCR), is becoming an attractive Riser option.The paper provides a review of the various Riser systems that can be considered for turret-moored FPSOs, and specific emphasis on Steel Lazy Wave Risers. A detailed case study of Steel Lazy Wave Risers for a typical turret moored FPSO with disconnectable turret is presented. This system is described in terms of design and functionalities, the fabrication and installation methods are presented. The case study shows clearly that SLWR are an attractive alternative to be used for FPSO with disconnectable turret and is very efficient to fabricate and install in a very cost effective manner.Pros and Cons for SLWR are discussed, with consideration of the particular challenges of turret-moored FPSOs with large floater motions, hang-off geometry constraints at turret, hang-off loads, Riser interferences, Risers pre-installation, and turret disconnection constraints.Copyright © 2015 by ASME
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drilling Riser viv tests with prototype reynolds numbers
ASME 2013 32nd International Conference on Ocean Offshore and Arctic Engineering, 2013Co-Authors: Henning Braaten, Jamison Szwalek, Massimiliano Russo, Rolf BaarholmAbstract:For deep-water Riser systems, Vortex Induced Vibrations (VIV) may cause significant fatigue damage. It appears that the knowledge gap of this phenomenon is considerable and this has caused a high level of research activity over the last decades. Small scale model tests are often used to investigate VIV behaviour. However, one substantial uncertainty in applying such results is scaling effects, i.e. differences in VIV response in full scale flow and small scale flow. To (partly) overcome this obstacle, a new innovative VIV test rig was designed and built at MARINTEK to test a rigid full scale Riser model. The rigid Riser model is mounted vertically and can either be elastically mounted or be given a forced motion. In the present version, the cylinder can only move in the cross-flow (CF) direction and is restricted in the in-line (IL) direction.The paper reports results from a drilling Riser VIV experiment where the new rest rig has been used. The overall objective of the work is to study possible VIV suppression to improve operability of retrievable Riser systems with auxiliary lines by adding Riser fins. These fins are normally used as devices for protection of the auxiliary lines.The test program has recently been completed and analysis is an on-going activity. However, some results can be reported at this stage and more results are planned to be published.A bare Riser model was used in a Reynolds number (Rn) scaling effect study. The Riser model was elastically mounted and towed over a reduced velocity range around 4 – 10 in two different Rn ranges, 75 000 – 192 000 (subcritical regime) and 347 000 – 553 000 (critical regime). The difference in the displacement amplitude to diameter ratio, A/D, is found to be significant.The elastically mounted Riser was also towed with various drilling Riser Configurations in order to study VIV/galloping responses. One Configuration included a slick joint Riser model with 6 kill & choke lines; another has added Riser fins too. The Riser model is based on a specific drilling Riser and the kill and choke lines have various diameters and have a non-symmetrical layout.The various Riser Configurations have also been used in forced motion tests where the towed model has been given a sinusoidal CF motion. Forces have been measured. Determination of the force coefficients is still in progress and is planned to be reported later.Scaling effects appear to be a significant uncertainty and further research on the subject is recommended.The slick joint drilling Riser Configuration generally increased the displacements compared to displacements of the bare Riser model. The drilling Riser Configuration with protection fins, kill and choke lines generally reduced the displacements compared to displacements of the bare Riser model. For both Riser systems, tests showed that the response is sensitive to the heading of the current.Copyright © 2013 by ASME
Y Drobyshevski - One of the best experts on this subject based on the ideXlab platform.
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integrated analysis of mooring and Riser systems for fpso s in harsh shallow water environments
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: M Martens, J R Whelan, Y DrobyshevskiAbstract:Shallow water mooring and Riser systems for permanently turret moored FPSOs present significant design challenges. Many FPSOs, in particular in the South-East Asia region, are required to remain on-station in 100-year return period tropical revolving storm (typhoon) conditions. Extreme sea states combined with the restricted height of the water column generate large mooring loads and make it difficult to accommodate conventional Riser Configurations. Metocean conditions in such areas can be highly directional. This directionality can be exploited by undertaking an integrated mooring and Riser design analysis. The critical interface between the mooring and Riser systems is the turret offset and the associated turret heave. The conventional approach is to identify a single offset envelope for each design case, comprising the mooring system (intact or damaged) and FPSO condition (loaded or ballasted), which is then used in Riser design. This paper presents a more developed approach, the integrated approach, which is based on conducting the mooring and Riser analyses simultaneously for a common set of design cases. To exploit the directionality of the metocean conditions, an offset envelope for each governing metocean condition is calculated from time domain mooring simulations, followed by a parameterisation scheme. As a result, multiple turret offsets and associated metocean conditions and FPSO headings are identified which form a family of offsets for each compass octant of the environment. The integrated approach is applied to an example FPSO with an external turret supporting seven Risers arranged in double wave tethered Configuration. The drivers and advantages for selecting a particular Riser Configuration are discussed. It is shown how application of an integrated analysis approach leads to less conservative combinations for use in the Riser design, and enables the development of a feasible Riser system. An optimal mooring pattern, both leg make-up and orientation for Riser layout, is also developed.Copyright © 2011 by ASME
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integrated analysis of mooring and Riser systems for fpso s in harsh shallow water environments
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: M Martens, J R Whelan, Y DrobyshevskiAbstract:Shallow water mooring and Riser systems for permanently turret moored FPSOs present significant design challenges. Many FPSOs, in particular in the South-East Asia region, are required to remain on-station in 100-year return period tropical revolving storm (typhoon) conditions. Extreme sea states combined with the restricted height of the water column generate large mooring loads and make it difficult to accommodate conventional Riser Configurations. Metocean conditions in such areas can be highly directional. This directionality can be exploited by undertaking an integrated mooring and Riser design analysis. The critical interface between the mooring and Riser systems is the turret offset and the associated turret heave. The conventional approach is to identify a single offset envelope for each design case, comprising the mooring system (intact or damaged) and FPSO condition (loaded or ballasted), which is then used in Riser design. This paper presents a more developed approach, the integrated approach, which is based on conducting the mooring and Riser analyses simultaneously for a common set of design cases. To exploit the directionality of the metocean conditions, an offset envelope for each governing metocean condition is calculated from time domain mooring simulations, followed by a parameterisation scheme. As a result, multiple turret offsets and associated metocean conditions and FPSO headings are identified which form a family of offsets for each compass octant of the environment. The integrated approach is applied to an example FPSO with an external turret supporting seven Risers arranged in double wave tethered Configuration. The drivers and advantages for selecting a particular Riser Configuration are discussed. It is shown how application of an integrated analysis approach leads to less conservative combinations for use in the Riser design, and enables the development of a feasible Riser system. An optimal mooring pattern, both leg make-up and orientation for Riser layout, is also developed.Copyright © 2011 by ASME
M Martens - One of the best experts on this subject based on the ideXlab platform.
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integrated analysis of mooring and Riser systems for fpso s in harsh shallow water environments
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: M Martens, J R Whelan, Y DrobyshevskiAbstract:Shallow water mooring and Riser systems for permanently turret moored FPSOs present significant design challenges. Many FPSOs, in particular in the South-East Asia region, are required to remain on-station in 100-year return period tropical revolving storm (typhoon) conditions. Extreme sea states combined with the restricted height of the water column generate large mooring loads and make it difficult to accommodate conventional Riser Configurations. Metocean conditions in such areas can be highly directional. This directionality can be exploited by undertaking an integrated mooring and Riser design analysis. The critical interface between the mooring and Riser systems is the turret offset and the associated turret heave. The conventional approach is to identify a single offset envelope for each design case, comprising the mooring system (intact or damaged) and FPSO condition (loaded or ballasted), which is then used in Riser design. This paper presents a more developed approach, the integrated approach, which is based on conducting the mooring and Riser analyses simultaneously for a common set of design cases. To exploit the directionality of the metocean conditions, an offset envelope for each governing metocean condition is calculated from time domain mooring simulations, followed by a parameterisation scheme. As a result, multiple turret offsets and associated metocean conditions and FPSO headings are identified which form a family of offsets for each compass octant of the environment. The integrated approach is applied to an example FPSO with an external turret supporting seven Risers arranged in double wave tethered Configuration. The drivers and advantages for selecting a particular Riser Configuration are discussed. It is shown how application of an integrated analysis approach leads to less conservative combinations for use in the Riser design, and enables the development of a feasible Riser system. An optimal mooring pattern, both leg make-up and orientation for Riser layout, is also developed.Copyright © 2011 by ASME
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integrated analysis of mooring and Riser systems for fpso s in harsh shallow water environments
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: M Martens, J R Whelan, Y DrobyshevskiAbstract:Shallow water mooring and Riser systems for permanently turret moored FPSOs present significant design challenges. Many FPSOs, in particular in the South-East Asia region, are required to remain on-station in 100-year return period tropical revolving storm (typhoon) conditions. Extreme sea states combined with the restricted height of the water column generate large mooring loads and make it difficult to accommodate conventional Riser Configurations. Metocean conditions in such areas can be highly directional. This directionality can be exploited by undertaking an integrated mooring and Riser design analysis. The critical interface between the mooring and Riser systems is the turret offset and the associated turret heave. The conventional approach is to identify a single offset envelope for each design case, comprising the mooring system (intact or damaged) and FPSO condition (loaded or ballasted), which is then used in Riser design. This paper presents a more developed approach, the integrated approach, which is based on conducting the mooring and Riser analyses simultaneously for a common set of design cases. To exploit the directionality of the metocean conditions, an offset envelope for each governing metocean condition is calculated from time domain mooring simulations, followed by a parameterisation scheme. As a result, multiple turret offsets and associated metocean conditions and FPSO headings are identified which form a family of offsets for each compass octant of the environment. The integrated approach is applied to an example FPSO with an external turret supporting seven Risers arranged in double wave tethered Configuration. The drivers and advantages for selecting a particular Riser Configuration are discussed. It is shown how application of an integrated analysis approach leads to less conservative combinations for use in the Riser design, and enables the development of a feasible Riser system. An optimal mooring pattern, both leg make-up and orientation for Riser layout, is also developed.Copyright © 2011 by ASME
Mark Oconnor - One of the best experts on this subject based on the ideXlab platform.
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the evolution of lazy s flexible Riser Configuration design for harsh environments
ASME 2012 31st International Conference on Ocean Offshore and Arctic Engineering, 2012Co-Authors: Keith Anderson, Mark OconnorAbstract:Flexible Riser Configurations in harsh environments require Riser buoyancy in order to decouple vessel induced motions from the seabed interface. This is achieved through either wave (distributed buoyancy) or S (subsea buoy) solutions.In the UK sector of the North Sea circa 30% of all floating production system field developments utilise subsea buoys in Lazy-S Configurations. The majority of these fields have been in service for many years and designed prior to the widespread adoption of current industry standards, the analytical rigour available today, and better characterisation of the metocean environment. In many cases original system design has also been for 50yr return period conditions, compared to the specified 100yr return period events required in todays codes and standards, e.g. ISO 13628-2 [1].Therefore, when replacement Riser or life extension work is performed on existing structures or new developments are being designed there can be significant challenges in confirming the applicability of traditional system Configuration designs.The principal challenges with these Configurations is minimising sag bend compressions driven by differential buoy vs. vessel motions and maintaining the Riser or umbilical minimum curvature and compression criteria at the seabed touch down. The latter point is a particular problem for umbilicals routed via Lazy-S Configurations owing to their relatively low weight and stiffness, and constraining MBR criteria.This paper considers the applicability of Lazy-S Configurations as a solution to modern harsh environment field developments and the evolution in Lazy-S system design to address the design challenges with particular emphasis on the TDP response.Copyright © 2012 by ASME
J R Whelan - One of the best experts on this subject based on the ideXlab platform.
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integrated analysis of mooring and Riser systems for fpso s in harsh shallow water environments
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: M Martens, J R Whelan, Y DrobyshevskiAbstract:Shallow water mooring and Riser systems for permanently turret moored FPSOs present significant design challenges. Many FPSOs, in particular in the South-East Asia region, are required to remain on-station in 100-year return period tropical revolving storm (typhoon) conditions. Extreme sea states combined with the restricted height of the water column generate large mooring loads and make it difficult to accommodate conventional Riser Configurations. Metocean conditions in such areas can be highly directional. This directionality can be exploited by undertaking an integrated mooring and Riser design analysis. The critical interface between the mooring and Riser systems is the turret offset and the associated turret heave. The conventional approach is to identify a single offset envelope for each design case, comprising the mooring system (intact or damaged) and FPSO condition (loaded or ballasted), which is then used in Riser design. This paper presents a more developed approach, the integrated approach, which is based on conducting the mooring and Riser analyses simultaneously for a common set of design cases. To exploit the directionality of the metocean conditions, an offset envelope for each governing metocean condition is calculated from time domain mooring simulations, followed by a parameterisation scheme. As a result, multiple turret offsets and associated metocean conditions and FPSO headings are identified which form a family of offsets for each compass octant of the environment. The integrated approach is applied to an example FPSO with an external turret supporting seven Risers arranged in double wave tethered Configuration. The drivers and advantages for selecting a particular Riser Configuration are discussed. It is shown how application of an integrated analysis approach leads to less conservative combinations for use in the Riser design, and enables the development of a feasible Riser system. An optimal mooring pattern, both leg make-up and orientation for Riser layout, is also developed.Copyright © 2011 by ASME
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integrated analysis of mooring and Riser systems for fpso s in harsh shallow water environments
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: M Martens, J R Whelan, Y DrobyshevskiAbstract:Shallow water mooring and Riser systems for permanently turret moored FPSOs present significant design challenges. Many FPSOs, in particular in the South-East Asia region, are required to remain on-station in 100-year return period tropical revolving storm (typhoon) conditions. Extreme sea states combined with the restricted height of the water column generate large mooring loads and make it difficult to accommodate conventional Riser Configurations. Metocean conditions in such areas can be highly directional. This directionality can be exploited by undertaking an integrated mooring and Riser design analysis. The critical interface between the mooring and Riser systems is the turret offset and the associated turret heave. The conventional approach is to identify a single offset envelope for each design case, comprising the mooring system (intact or damaged) and FPSO condition (loaded or ballasted), which is then used in Riser design. This paper presents a more developed approach, the integrated approach, which is based on conducting the mooring and Riser analyses simultaneously for a common set of design cases. To exploit the directionality of the metocean conditions, an offset envelope for each governing metocean condition is calculated from time domain mooring simulations, followed by a parameterisation scheme. As a result, multiple turret offsets and associated metocean conditions and FPSO headings are identified which form a family of offsets for each compass octant of the environment. The integrated approach is applied to an example FPSO with an external turret supporting seven Risers arranged in double wave tethered Configuration. The drivers and advantages for selecting a particular Riser Configuration are discussed. It is shown how application of an integrated analysis approach leads to less conservative combinations for use in the Riser design, and enables the development of a feasible Riser system. An optimal mooring pattern, both leg make-up and orientation for Riser layout, is also developed.Copyright © 2011 by ASME
