The Experts below are selected from a list of 132 Experts worldwide ranked by ideXlab platform
Jean-luc Legras - One of the best experts on this subject based on the ideXlab platform.
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Impact on Risers and Flowlines Design of the FPSO Mooring in Deepwater and Ultra Deepwater
Day 2 Tue May 06 2014, 2014Co-Authors: Jean-francois Saint-marcoux, Jean-luc LegrasAbstract:Abstract Ten years back the choice between turret-moored FPSO and spread-moored FPSOs was primarily dictated by local met ocean conditions: spread moored FPSO in West Africa, soft-(DICAS) mooring FPSO in Brazil, and turret-moored FPSO elsewhere. Over the recent years West Africa is turning to turret-moored FPSOs (internal and external), and Brazil has installed spread-moored FPSOs. Whereas spread moored FPSOs prevail in larger sizes (about 2MB), new built, turret-moored, FPSOs are usually smaller in size (1MB) with external-turret offering cost and schedule benefits to the operators over internal-turrets. This paper presents the impact of this new trend in FPSO mooring on the design of the flow lines and risers and related impact to field layout. The orientation of a spread-mooring is governed by the local met ocean conditions and may not be optimal for the routing of the flowlines; also compromises may have to be done with regards to flow assurance constraints. Turret-moored FPSO allow possibly a better use of the seafloor space especially in deeper water where the seafloor slope is gentler, and result in shorter flowlines. Risers for spread-moored FPSOs are decoupled unless they can be a small number and limited to the central part of the hull. For turret-moored FPSO, decoupled risers allow larger FPSO offset movements and are compatible with both internal and external turret. In the case of SHR or HRT, safety rules impose a significantly longer jumper lines to protect the FPSO from accidental Buoyancy Tank release. SCRs may also be feasible but highly insulated risers are very light and prone to fatigue in-service. Examples are being provided to evaluate the impact of the various FPSO mooring options.
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Tethered Catenary Riser: A Novel Concept for Ultradeep Water
All Days, 2013Co-Authors: Jean-luc LegrasAbstract:Abstract A new riser concept is proposed by Subsea 7 for field development in deep and ultradeep waters: the Tethered Catenary Riser (TCR)-patent pending. The concept consists of a number of steel catenary risers supported by a subsurface buoy which is tethered down to sea-bed by means of a single pipe tendon and anchored by means of a suction pile; flexible jumpers are used to make the connection between the Floating production Unit (FPU) and the buoy. Umbilicals run without interruption from the FPU to their subsea end while being supported by the buoy. The system has all the advantages of de-coupled riser arrangements: flexible jumpers effectively absorb platform motions, thereby the rigid risers and tendon have very small dynamic excitation. The system can be installed before FPU arrival on site, which improves the time before first oil. Analyses have shown that, with adequate geometry of the buoy, the latter is sufficient stable to induce acceptable tilt and twist when different arrangements of SCRs and flexible jumpers are installed, and under accidental scenarios during the in-place life. The riser system is best designed for a number of risers between 4 and 8, in addition to a number of umbilicals, thus convenient for one or two drilling centers. Results of the basic engineering work on the TCR clearly indicate that it is possible to have a robust design using presently qualified materials and technology. The components used in the TCR are all field proven as they are commonly used in existing riser systems. As a result of installation studies, a method very similar to the one commonly used by Subea7 for Single Hybrid Risers (SHRs) has been selected for the buoy and tether system. Placement of rigid risers, jumpers and umbilicals is as done by Subsea 7 for the BSRs. This method is well adapted for installation by the new Subsea 7 flagship vessel Seven Borealis which is able to perform heavy lift and pipe laying. The Tether Catenary Riser is a credible option for use in deep water developments all over the world. Since all the components, design methods and installation procedures are fully qualified and familiar to Subsea 7, the concept is cost effective and ready for project application. Introduction A lot of well proven riser concepts have been used in deepwater for different environments, in particular, steel or flexible risers in catenary or lazy-wave shape, and single or bundle Hybrid Riser Towers (HRTs). Nevertheless, for some application new concepts are deemed more attractive and selected, as the Buoy Supporting Riser (BSR) for ultra-deep water offshore Brazil. But other ideas of riser concept emerge from the review and comparison of pros and cons of existing riser systems, trying to take the better of each one. The TCR is an adaptation of the BSR, but with a simpler tether arrangement and easier installation method. It can also be seen as a SHR with a number of SCRs attached to the Buoyancy Tank. The concept is described below as well as design methodology, application example and installation outline procedures.
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Lessons Learned on the Design and Construction of Hybrid Riser Towers
All Days, 2011Co-Authors: Jean-francois Saint-marcoux, Jean-luc LegrasAbstract:Abstract Compliant Risers cover many different types of risers. Even among self-standing compliant risers, different architectures are possible. Nevertheless the paper will concentrate on bundle Hybrid Riser Towers (bundle-HRT). The paper will describe the several choices to be made for the design of a bundle-HRT. The selection is driven by the functional requirements, but also through the lessons learned and through reliability. Then the paper will review the various components of the bundle-HRT (Foundation, Lower Termination Assembly, Bundle, Upper Termination Assembly, Buoyancy Tank, Jumpers), and describe how each component incorporates the particular requirements of the project. Finally the paper will detail how the lessons learned on previous projects have been systematically introduced in the design of the following generation. 1.0 General Evolution of Hybrid Riser Towers The use of Hybrid Riser Towers now spreads over three decades. Early patents were filed in the late seventies (Panicker 1980). Research was conducted in particular by Mobil Corporation alone and then in cooperation with Institut Francais du Petrole -IFP - (Goodfellow Associates 1990). The first actual projects were carried out in the late eighties and early nineties in the Gulf of Mexico, first for Green Canyon 29 (Fisher 1988), then for Garden Banks 388 (Fisher 1995). The unit build for GC 29 was recovered, refurbished, extended, and reused for GB 388. Clearly drilling risers design was the blue-print of early hybrid riser designs. In particular the risers were jointed with threaded connection and were installed by semi-submersible drilling rigs.
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Management of Hybrid Riser Towers Integrity
All Days, 2011Co-Authors: Jean-luc Legras, Jean-francois Saint-marcouxAbstract:Abstract Field developments target deeper and deeper waters, for which Hybrid Riser Towers (HRTs) have become one of the solutions investigated almost systematically at bid stage. This is due, particular, to the capability of HRT's to accommodate the requirement for large diameter risers, reduced load on FPSO, demanding flow assurance requirements, and robust layout for later developments phases. Requirements of Integrity Management (IM) are nowadays at the heart of all offshore development; they are included in the criteria for selection of a riser system. Application of IM principles to a HRT project are summarized with the perspective of the Contractor. The first IM activity is a comprehensive risk assessment which requires the review of all components of the subsea system from wellhead to FPSO; all parts of the preferred architecture of a Bundle HRT (BHRT) are addressed here with emphasis on IM issues and the main failure modes identified. Finally a typical monitoring system of a BHRT is described as well as inspection; indeed it is from their results that the IM plan can be implemented during the operating phase of the project. Introduction HRTs include BHRTs and Single Hybrid Risers (SHRs) which have in common to be anchored in the seabed, include rigid pipe over the most part of the water depth, be tensioned by a Buoyancy Tank at the top, and linked to a Floating Production Unit (FPU) by a flexible. BHRTs that are mainly considered here are more complex because of the plurality of pipes of the column arrangement and of the specific installation method. Recent applications of BHRTs are offshore West Africa with now more than ten years of operation on the Girassol field, but designs at FEED stage have been made for ultra deep water fields of the Gulf of Mexico and Petrobras Pre-salt offshore Brazil. A practical example application of an IM plan has been proposed and implemented by Total for the Girassol BHRT's (Chapin, 2005). Since then the industry has set in place a Joint Industry Program (SCRIM JIP, 2007) for the integrity management of Steel Catenary Risers, and the program of this JIP has been extended to cover HRT's. The subject is also addressed in the DNV RP F206. The main IM activities are summarized below. From the Girassol (Rouillon, 2002) and Greater Plutonio (Sworn, 2005) experience, Subsea 7 (Alliot, Legras, 2006) has analyzed the lessons learned from these bundle HRT based projects. This has lead to an architecture which will be detailed hereafter and screened for the failure modes. Dynamic risers require attention because of the dynamic nature of their loading, whether this is due to their environment or to the fluid they convey. Companies have long recognized the importance of monitoring these and results are essential input for the fitness statements to be carried out during operation of the riser system.
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Design of the Greater Plutonio Riser Tower
Volume 3: Pipeline and Riser Technology, 2009Co-Authors: Francis Djia, Charles-alexandre Zimmermann, Daniel De La Cruz, Gre´goire De Roux, Jean-luc LegrasAbstract:The Greater Plutonio Riser Tower is installed in Angola in a Water depth of 1310 meters (4300 feet), and gathers 11 risers (two production loops, three water injection, one gas injection and three gas lift lines) and one gas lift umbilical. The total mass of this unique riser system is more than 4000 tons. This paper aims at describing the main challenges associated to the Riser Tower design. After a description of the riser tower main elements (flexible jumpers, Buoyancy Tank, guiding frames welded to the core pipe, gas lift manifolds...), numerical analyses are presented (in place extreme and fatigue analyses). Assessment of the friction developed by the risers against the guiding frames and associated effects on the global behaviour of the riser tower are detailed. Various sources of conservatism, lessons learned and ways of improvements are also shared for future projects.
Charles-alexandre Zimmermann - One of the best experts on this subject based on the ideXlab platform.
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The Greater Plutonio Riser Tower.
All Days, 2009Co-Authors: Daniel De La Cruz, Charles-alexandre Zimmermann, Pierre Neveux, Franck LouvetyAbstract:Abstract The paper presents a general overview of the Greater Plutonio Hybrid Riser Tower. It covers the various phases that led to the realization of this unique system: conception, procurement, fabrication, offshore installation and start up. This Riser Tower is now installed and operating in Angola in a water depth of 1310m (4300 feet). It gathers 11 risers and one umbilical. It is the largest in diameter and weight installed in the world so far. After concept selection and a detailed design phase, all elements were procured from numerous suppliers and assembled on the Lobito yard in Angola. The tower was then towed in a submerged configuration and upended on the Greater Plutonio site. It was then anchored in position, connected to the flowlines and the FPSO before being tested and used for production. Some lessons learned for future projects by the Oil Company and the Contractor with particular emphasis on the possibility of extending the use of this concept in ultra deepwater are presented. Introduction The Hybrid Riser Tower (HRT) is one of the riser system concepts suitable for deep and ultra deep water field developments. This concept has been used previously on the Garden Banks, Girassol and Rosa Lirio fields. The Greater Plutonio HRT is believed to be the largest installed in the world today. It allows conveying all production and injection fluids of the five BP operated fields on the Greater Plutonio site which are: Galio, Cromio, Paladio, Cobalto and Plutonio. In comparison, the oil production passing through this tower is about the same as the one passing through the three towers of the Girassol field. The Greater Plutonio HRT was part of a turnkey contract executed by Acergy to provide Umbilicals, Risers and Flowlines to BP and its partners to allow production, injection, mooring, offloading and control functions between the Subsea Production Systems and a spread moored FPSO. The contract was awarded in February 2004 and the first oil production occurred in October 2007. The present paper provides an overview of the main phases leading to the delivery of the Riser Tower package within the project and some associated Lessons Learned. Description of the tower The riser configuration selected for the Greater Plutonio Field Development consists of one single Riser Tower, with a Buoyancy Tank. The overall configuration is shown hereunder. A riser tower is a bundle of several risers, anchored to the seabed and tensioned by means of Buoyancy. It is connected to the FPSO by means of flexible jumpers and to the seabed flowlines termination assemblies by means of spools. These spools are designed to accommodate tower inclination (mainly due to the FPSO excursions), as well as expansion of both risers and flowlines.
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Greater Plutonio Riser Tower Installation: Studies and Lessons Learnt
Volume 3: Pipeline and Riser Technology, 2009Co-Authors: Charles-alexandre Zimmermann, Guilhem Layrisse, Daniel De La Cruz, Jeremy GordonnatAbstract:The BP operated Greater Plutonio field development offshore Angola comprises a spread-moored FPSO in 1,300 m water depth, serving as a hub processing the fluids produced from or injected into the subsea wells. The selected riser system is a Hybrid Riser Tower comprising 11 risers bundled around a central structural tubular (Core Pipe), tensioned by a steel Buoyancy Tank at its top and maintained by an anchor base at its bottom. The Riser Tower is fabricated onshore and then towed to the field for final installation in deepwater near the FPSO. Once the Riser Tower installation is completed the risers are connected to the FPSO by means of flexible jumpers and to the flowlines by means of rigid spools. All fabrication and installation work has been performed by Acergy. This paper presents the studies performed to cover all the steps of the installation phase: build-up of the Orcaflex model, miscellaneous studies to determine model and analyses parameters, towing analysis, upending analysis, Buoyancy Tank ballasting and deballasting analyses, and contingency analyses. This paper is mainly focused on the Riser Tower installation but also covers the installation of the Riser Tower anchor and of the flexible jumpers in order to give a complete overview of the operations related to the Riser Tower system. A comparison between computed data and data measured during operations is also presented to support the overall installation analysis methodology. Lessons learned are provided for future improvement of Riser Tower installation covering main challenges such as Riser Tower modeling, weight/Buoyancy repartition along the Riser Tower, Buoyancy Tank ballasting adjustment in Lobito bay, fatigue issues during surface and subsurface tow, bending moment issues during upending, etc.Copyright © 2009 by ASME
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Design of the Greater Plutonio Riser Tower
Volume 3: Pipeline and Riser Technology, 2009Co-Authors: Francis Djia, Charles-alexandre Zimmermann, Daniel De La Cruz, Gre´goire De Roux, Jean-luc LegrasAbstract:The Greater Plutonio Riser Tower is installed in Angola in a Water depth of 1310 meters (4300 feet), and gathers 11 risers (two production loops, three water injection, one gas injection and three gas lift lines) and one gas lift umbilical. The total mass of this unique riser system is more than 4000 tons. This paper aims at describing the main challenges associated to the Riser Tower design. After a description of the riser tower main elements (flexible jumpers, Buoyancy Tank, guiding frames welded to the core pipe, gas lift manifolds...), numerical analyses are presented (in place extreme and fatigue analyses). Assessment of the friction developed by the risers against the guiding frames and associated effects on the global behaviour of the riser tower are detailed. Various sources of conservatism, lessons learned and ways of improvements are also shared for future projects.
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Design of the Greater Plutonio Riser Tower
Volume 3: Pipeline and Riser Technology, 2009Co-Authors: Francis Djia, Charles-alexandre Zimmermann, Daniel De La Cruz, Gre´goire De Roux, Jean-luc LegrasAbstract:The Greater Plutonio Riser Tower is installed in Angola in a Water depth of 1310 meters (4300 feet), and gathers 11 risers (two production loops, three water injection, one gas injection and three gas lift lines) and one gas lift umbilical. The total mass of this unique riser system is more than 4000 tons. This paper aims at describing the main challenges associated to the Riser Tower design. After a description of the riser tower main elements (flexible jumpers, Buoyancy Tank, guiding frames welded to the core pipe, gas lift manifolds...), numerical analyses are presented (in place extreme and fatigue analyses). Assessment of the friction developed by the risers against the guiding frames and associated effects on the global behaviour of the riser tower are detailed. Various sources of conservatism, lessons learned and ways of improvements are also shared for future projects.Copyright © 2009 by ASME
Daniel De La Cruz - One of the best experts on this subject based on the ideXlab platform.
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The Greater Plutonio Riser Tower.
All Days, 2009Co-Authors: Daniel De La Cruz, Charles-alexandre Zimmermann, Pierre Neveux, Franck LouvetyAbstract:Abstract The paper presents a general overview of the Greater Plutonio Hybrid Riser Tower. It covers the various phases that led to the realization of this unique system: conception, procurement, fabrication, offshore installation and start up. This Riser Tower is now installed and operating in Angola in a water depth of 1310m (4300 feet). It gathers 11 risers and one umbilical. It is the largest in diameter and weight installed in the world so far. After concept selection and a detailed design phase, all elements were procured from numerous suppliers and assembled on the Lobito yard in Angola. The tower was then towed in a submerged configuration and upended on the Greater Plutonio site. It was then anchored in position, connected to the flowlines and the FPSO before being tested and used for production. Some lessons learned for future projects by the Oil Company and the Contractor with particular emphasis on the possibility of extending the use of this concept in ultra deepwater are presented. Introduction The Hybrid Riser Tower (HRT) is one of the riser system concepts suitable for deep and ultra deep water field developments. This concept has been used previously on the Garden Banks, Girassol and Rosa Lirio fields. The Greater Plutonio HRT is believed to be the largest installed in the world today. It allows conveying all production and injection fluids of the five BP operated fields on the Greater Plutonio site which are: Galio, Cromio, Paladio, Cobalto and Plutonio. In comparison, the oil production passing through this tower is about the same as the one passing through the three towers of the Girassol field. The Greater Plutonio HRT was part of a turnkey contract executed by Acergy to provide Umbilicals, Risers and Flowlines to BP and its partners to allow production, injection, mooring, offloading and control functions between the Subsea Production Systems and a spread moored FPSO. The contract was awarded in February 2004 and the first oil production occurred in October 2007. The present paper provides an overview of the main phases leading to the delivery of the Riser Tower package within the project and some associated Lessons Learned. Description of the tower The riser configuration selected for the Greater Plutonio Field Development consists of one single Riser Tower, with a Buoyancy Tank. The overall configuration is shown hereunder. A riser tower is a bundle of several risers, anchored to the seabed and tensioned by means of Buoyancy. It is connected to the FPSO by means of flexible jumpers and to the seabed flowlines termination assemblies by means of spools. These spools are designed to accommodate tower inclination (mainly due to the FPSO excursions), as well as expansion of both risers and flowlines.
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Greater Plutonio Riser Tower Installation: Studies and Lessons Learnt
Volume 3: Pipeline and Riser Technology, 2009Co-Authors: Charles-alexandre Zimmermann, Guilhem Layrisse, Daniel De La Cruz, Jeremy GordonnatAbstract:The BP operated Greater Plutonio field development offshore Angola comprises a spread-moored FPSO in 1,300 m water depth, serving as a hub processing the fluids produced from or injected into the subsea wells. The selected riser system is a Hybrid Riser Tower comprising 11 risers bundled around a central structural tubular (Core Pipe), tensioned by a steel Buoyancy Tank at its top and maintained by an anchor base at its bottom. The Riser Tower is fabricated onshore and then towed to the field for final installation in deepwater near the FPSO. Once the Riser Tower installation is completed the risers are connected to the FPSO by means of flexible jumpers and to the flowlines by means of rigid spools. All fabrication and installation work has been performed by Acergy. This paper presents the studies performed to cover all the steps of the installation phase: build-up of the Orcaflex model, miscellaneous studies to determine model and analyses parameters, towing analysis, upending analysis, Buoyancy Tank ballasting and deballasting analyses, and contingency analyses. This paper is mainly focused on the Riser Tower installation but also covers the installation of the Riser Tower anchor and of the flexible jumpers in order to give a complete overview of the operations related to the Riser Tower system. A comparison between computed data and data measured during operations is also presented to support the overall installation analysis methodology. Lessons learned are provided for future improvement of Riser Tower installation covering main challenges such as Riser Tower modeling, weight/Buoyancy repartition along the Riser Tower, Buoyancy Tank ballasting adjustment in Lobito bay, fatigue issues during surface and subsurface tow, bending moment issues during upending, etc.Copyright © 2009 by ASME
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Design of the Greater Plutonio Riser Tower
Volume 3: Pipeline and Riser Technology, 2009Co-Authors: Francis Djia, Charles-alexandre Zimmermann, Daniel De La Cruz, Gre´goire De Roux, Jean-luc LegrasAbstract:The Greater Plutonio Riser Tower is installed in Angola in a Water depth of 1310 meters (4300 feet), and gathers 11 risers (two production loops, three water injection, one gas injection and three gas lift lines) and one gas lift umbilical. The total mass of this unique riser system is more than 4000 tons. This paper aims at describing the main challenges associated to the Riser Tower design. After a description of the riser tower main elements (flexible jumpers, Buoyancy Tank, guiding frames welded to the core pipe, gas lift manifolds...), numerical analyses are presented (in place extreme and fatigue analyses). Assessment of the friction developed by the risers against the guiding frames and associated effects on the global behaviour of the riser tower are detailed. Various sources of conservatism, lessons learned and ways of improvements are also shared for future projects.
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Design of the Greater Plutonio Riser Tower
Volume 3: Pipeline and Riser Technology, 2009Co-Authors: Francis Djia, Charles-alexandre Zimmermann, Daniel De La Cruz, Gre´goire De Roux, Jean-luc LegrasAbstract:The Greater Plutonio Riser Tower is installed in Angola in a Water depth of 1310 meters (4300 feet), and gathers 11 risers (two production loops, three water injection, one gas injection and three gas lift lines) and one gas lift umbilical. The total mass of this unique riser system is more than 4000 tons. This paper aims at describing the main challenges associated to the Riser Tower design. After a description of the riser tower main elements (flexible jumpers, Buoyancy Tank, guiding frames welded to the core pipe, gas lift manifolds...), numerical analyses are presented (in place extreme and fatigue analyses). Assessment of the friction developed by the risers against the guiding frames and associated effects on the global behaviour of the riser tower are detailed. Various sources of conservatism, lessons learned and ways of improvements are also shared for future projects.Copyright © 2009 by ASME
Lyu Don - One of the best experts on this subject based on the ideXlab platform.
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Structural strength analysis on Buoyancy Tank of middle water arch
Computer-Aided Engineering, 2014Co-Authors: Lyu DonAbstract:As to the Buoyancy Tanks of middle water arch which is the accessory of the dynamic flexible pipe /cable system used in the shallow water,the structure features and functions are introduced and the basic parameters are given; the structural strength of the Buoyancy Tanks is analyzed by ANSYS,and the general rule of the effect of wall thickness change on the strength and mass of Buoyancy Tanks is obtained;the effect of Buoyancy Tank damage on the overall functionality of middle water arch is studied; the curve of Buoyancy Tank stress and chamfering radius of the connection between internal baffle plate and outer hull is summarized and the scope of the best chamfering radius is given. The research results can improve the safety and reliability and the design level of the middle water arch.
Jean-francois Saint-marcoux - One of the best experts on this subject based on the ideXlab platform.
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Impact on Risers and Flowlines Design of the FPSO Mooring in Deepwater and Ultra Deepwater
Day 2 Tue May 06 2014, 2014Co-Authors: Jean-francois Saint-marcoux, Jean-luc LegrasAbstract:Abstract Ten years back the choice between turret-moored FPSO and spread-moored FPSOs was primarily dictated by local met ocean conditions: spread moored FPSO in West Africa, soft-(DICAS) mooring FPSO in Brazil, and turret-moored FPSO elsewhere. Over the recent years West Africa is turning to turret-moored FPSOs (internal and external), and Brazil has installed spread-moored FPSOs. Whereas spread moored FPSOs prevail in larger sizes (about 2MB), new built, turret-moored, FPSOs are usually smaller in size (1MB) with external-turret offering cost and schedule benefits to the operators over internal-turrets. This paper presents the impact of this new trend in FPSO mooring on the design of the flow lines and risers and related impact to field layout. The orientation of a spread-mooring is governed by the local met ocean conditions and may not be optimal for the routing of the flowlines; also compromises may have to be done with regards to flow assurance constraints. Turret-moored FPSO allow possibly a better use of the seafloor space especially in deeper water where the seafloor slope is gentler, and result in shorter flowlines. Risers for spread-moored FPSOs are decoupled unless they can be a small number and limited to the central part of the hull. For turret-moored FPSO, decoupled risers allow larger FPSO offset movements and are compatible with both internal and external turret. In the case of SHR or HRT, safety rules impose a significantly longer jumper lines to protect the FPSO from accidental Buoyancy Tank release. SCRs may also be feasible but highly insulated risers are very light and prone to fatigue in-service. Examples are being provided to evaluate the impact of the various FPSO mooring options.
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Lessons Learned on the Design and Construction of Hybrid Riser Towers
All Days, 2011Co-Authors: Jean-francois Saint-marcoux, Jean-luc LegrasAbstract:Abstract Compliant Risers cover many different types of risers. Even among self-standing compliant risers, different architectures are possible. Nevertheless the paper will concentrate on bundle Hybrid Riser Towers (bundle-HRT). The paper will describe the several choices to be made for the design of a bundle-HRT. The selection is driven by the functional requirements, but also through the lessons learned and through reliability. Then the paper will review the various components of the bundle-HRT (Foundation, Lower Termination Assembly, Bundle, Upper Termination Assembly, Buoyancy Tank, Jumpers), and describe how each component incorporates the particular requirements of the project. Finally the paper will detail how the lessons learned on previous projects have been systematically introduced in the design of the following generation. 1.0 General Evolution of Hybrid Riser Towers The use of Hybrid Riser Towers now spreads over three decades. Early patents were filed in the late seventies (Panicker 1980). Research was conducted in particular by Mobil Corporation alone and then in cooperation with Institut Francais du Petrole -IFP - (Goodfellow Associates 1990). The first actual projects were carried out in the late eighties and early nineties in the Gulf of Mexico, first for Green Canyon 29 (Fisher 1988), then for Garden Banks 388 (Fisher 1995). The unit build for GC 29 was recovered, refurbished, extended, and reused for GB 388. Clearly drilling risers design was the blue-print of early hybrid riser designs. In particular the risers were jointed with threaded connection and were installed by semi-submersible drilling rigs.
-
Management of Hybrid Riser Towers Integrity
All Days, 2011Co-Authors: Jean-luc Legras, Jean-francois Saint-marcouxAbstract:Abstract Field developments target deeper and deeper waters, for which Hybrid Riser Towers (HRTs) have become one of the solutions investigated almost systematically at bid stage. This is due, particular, to the capability of HRT's to accommodate the requirement for large diameter risers, reduced load on FPSO, demanding flow assurance requirements, and robust layout for later developments phases. Requirements of Integrity Management (IM) are nowadays at the heart of all offshore development; they are included in the criteria for selection of a riser system. Application of IM principles to a HRT project are summarized with the perspective of the Contractor. The first IM activity is a comprehensive risk assessment which requires the review of all components of the subsea system from wellhead to FPSO; all parts of the preferred architecture of a Bundle HRT (BHRT) are addressed here with emphasis on IM issues and the main failure modes identified. Finally a typical monitoring system of a BHRT is described as well as inspection; indeed it is from their results that the IM plan can be implemented during the operating phase of the project. Introduction HRTs include BHRTs and Single Hybrid Risers (SHRs) which have in common to be anchored in the seabed, include rigid pipe over the most part of the water depth, be tensioned by a Buoyancy Tank at the top, and linked to a Floating Production Unit (FPU) by a flexible. BHRTs that are mainly considered here are more complex because of the plurality of pipes of the column arrangement and of the specific installation method. Recent applications of BHRTs are offshore West Africa with now more than ten years of operation on the Girassol field, but designs at FEED stage have been made for ultra deep water fields of the Gulf of Mexico and Petrobras Pre-salt offshore Brazil. A practical example application of an IM plan has been proposed and implemented by Total for the Girassol BHRT's (Chapin, 2005). Since then the industry has set in place a Joint Industry Program (SCRIM JIP, 2007) for the integrity management of Steel Catenary Risers, and the program of this JIP has been extended to cover HRT's. The subject is also addressed in the DNV RP F206. The main IM activities are summarized below. From the Girassol (Rouillon, 2002) and Greater Plutonio (Sworn, 2005) experience, Subsea 7 (Alliot, Legras, 2006) has analyzed the lessons learned from these bundle HRT based projects. This has lead to an architecture which will be detailed hereafter and screened for the failure modes. Dynamic risers require attention because of the dynamic nature of their loading, whether this is due to their environment or to the fluid they convey. Companies have long recognized the importance of monitoring these and results are essential input for the fitness statements to be carried out during operation of the riser system.
