Deep Water Steel Catenary Systems Installation Marin Abélanet, Subsea 7, Daniel Karunakaran, Subsea 7, Richard Jones, Subsea 7, Stéphan Eyssautier, Subsea 7 Patrick White, Subsea 7
Abstract Steel catenary risers (SCR) have been an attractive choice for deep-water field developments. This paper presents the latest advance and development of Subsea 7 technology in SCR configuration, fabrication and installation. It gives insight of deepwater SCRs from concept selection to ready for operation, and describes the fabrication process including consideration for welding operation, the latest development of Subsea 7 fleet for installation together with final hook up.Past experience of specific installation such as BC10 in Brazil will be shared.
Introduction Steel Catenary Risers (SCR) are an attractive choice for deepwater field developments. SCRs are simple in design with few complicated components. However, the design of SCRs requires high fatigue performance, especially at the top end and at sag bend. More and more often, risers are required to be wet stored on the seabed before the floating facility is moored in place for the risers to be hooked up. As SCRs are installed in deeper waters, their top tension increases beyond the capabilities of many existing vessels. This makes the installation of SCRs in deepwater challenging. The EPIC Contractor can improve the fatigue performance of SCR: By proposing the best riser configuration and installation method, they can reduce the motion that the SCR has to withstand during life of field and minimize the fatigue damage during installation. By focusing on welding technology improvement, they can increase the weld quality, which is particularly important for sour service where the welding of corrosion resistant alloys increases the complexity of the task. This paper will briefly present the different riser configurations: -
Free hanging SCR, Lazy Wave SCR, Buoyancy Supported Risers (BSR);
The different methods of installation: -
S-Lay, J-Lay, Reel Lay
And will describe solutions for overcoming the challenges of: -
Fatigue performance of Corrosion Resistant Alloy (CRA) weldings, especially in Reel Lay, Pre-installation of SCRs on the seabed and their subsequent recovery after the floating facility mooring for hook-up
And in particular share the experience and lessons learnt from the -
The first Lazy Wave SCR installed in Brazil for Shell BC-10 project, Wetstorage of SCR and recovery for Shell BC-10 in Brazil and Shell Gumusut in Malaysia.
Generalities on SCR Fatigue Design The SCRs usually require a fatigue life of 10 times their service life, which is equal to a total of 250 years in general. This results in a very large number of cycles and, even in mild environments, the accumulated fatigue damage is usually the main driver in dimensioning SCRs. The main causes of fatigue damage to risers are: • • • •
Shut-down and re-start Vortex Induced Vibration (VIV) Waves and associated riser excitation due to floating facilities motions Installation
Shut-down and re-start scenario is decided by oil operators and EPIC Contractor usually has no influence on this factor. VIVs are nowadays a much better known phenomenon: slender bodies interacting with an external fluid flow, produce periodical irregularities on this flow resulting in vibrations. If these vibrations’ period is close to the natural period of the system, this could lead to high amplitudes of movement and therefore high fatigue. Since sea current is usually strong in deepwater basins VIV is an especially relevant topic to deepwater SCRs.
Left Photo Courtesy of Langkhorst Mouldings
VIV Strakes going through Stinger Rollers, mounted under J-Lay Tower
The most common solution is to add helicoidal strakes to suppress the cause of these vibrations. It’s simple and efficient in-place. Their installation does not present major issues: They usually come in lightweight half-shells which do require additional time to be mounted offshore under the lay spread. In case the of S-Lay, the VIV Strakes have to pass through stinger rollers and therefore need to be very resistant to crush load and find their shape back after the exit of stinger. Waves and associated riser excitation due to floating facility motions are the main source of fatigue damage. It is obviously heavily dependant on weather conditions and the Response Amplitude Operators (RAOs) of the chosen floating facility. Both are given to the EPIC Contractor to propose the best riser configuration to suit.
Selecting the best SCR configuration: The first SCR was installed in the Gulf of Mexico in 1994 to a Tension Leg Platform (TLP) – Shell Auger Project. Some of the characteristics of a TLP is that it has minimal excursion and heave even under harsh conditions and can support high loads. The SCRs were therefore promoted as a cheaper alternative to flexible pipe. SCRs are usually free-hanging. They consist of a rigid pipe that may differ in thickness and/or grade from the static rigid flowline, directly welded onto it (at the “transition Point”) a few hundred metres from the Touch Down Point (TDP) or via an anchored subsea structure. At the top end, a Flexjoint or a Stressjoint makes the interface with the hang-off receptacle, which is part of the hull of the floating facility. SCRs are all the more sensitive to dynamics when they are light in water. This can be caused by the following: - Risers with thick insulation coating - Gas production or injection risers - Risers combining both of the above, Risers with these properties are less resistant to fatigue. However, some new configurations are emerging to tackle the issue of excessive fatigue damage at the TDP and at the top end. Subsea7 (formerly Acergy) started in 2008 to analyse different ways to improve the fatigue performance of SCRs by adding weight or buoyancies: Buoyancies have been added midwater along SCR to form a Lazy Wave in order to reduce the heave transmitted from the floating facility to the SCR at the TDP. It also reduces the load at the top. The best results were achieved with a minimum amount of buoyancy modules located close to the TDP.
Mini Lazy Wave Concept simulated in Orcaflex
The Weight Distributed SCR is a concept which enhances the applicability of SCRs to harsher environments. In this concept, well qualified ballast elements are attached at certain sections fo the SCR to reduce the stresses around the touchdown point and enhance the fatigue performance. Both Weight Distributed SCRs and Lazy Wave SCRs have been proven as a very good way to reduce the stress at the TDP. When compared to a free hanging SCR, such configurations SCR can have an increased fatigue life by a considerable factor of between x2 and x5.
Steel Lazy Wave Risers (SLWR) were first installed by Subsea7 for Shell in Brazil for BC-10 Project in 2009. This project is discussed further in coming sections. Another new concept is the Buoyancy Supported Riser (BSR) that is being developed for Petrobras Guara-Lula in Brazil pre-salt very deep water. This system completely decouples the motions of the floating facility by anchoring a large structure sub-surface which will support the catenary load of the SCRs. It is essentially a hybrid system where flexible pipes are used to join the buoyancy supported riser to the floating facility. The BSR concept is best suited to ultra-deepwater developments. Subsea7 is set to complete the design and installation of the first BSR by 2013-4.
Guara Lula – BSR Concept: Riser Configuration and Buoyancy General Arrangement
During installation, for a given SCR configuration, the fatigue accumulated can differ a lot depending on the selected vessel. There is no strict standard but a usual value for fatigue budget during installation is 5% of the total fatigue acceptable damage. The fatigue damage during installation is influenced by the following factors: -
-
-
Strain due to bending along the lay spread: o Reel Lay is the worst method in this respect as it imposes important bending in the pipe (plastic domain), o S-Lay also applies large bending moment combined with high tension, so much that supporting by stinger is required, o J-Lay is the best method in this respect as the hog bend is eliminated from the pipe path Exposure time to vessel motion during lay: o Reel Lay is the quickest method as it mainly consists in unspooling offshore o Stick-Lay (in J-shape or S-shape) is slower as welding NDE and Field-Joint Coating are performed in critical time ; lay time may be divided by 2 to 4 by double jointing or quad-jointing onshore (prefabricate strings of 2 or 4 pipe joints together onshore or in hidden time onboard) Motion at the lay spread location: o The vessel heave is critical to all methods as it induces compression and bending in the pipe at the TDP - the larger vessels should be preferred as they are more stable, o If the lay spread is close to the centre of the ship, the amplitude of pitch and roll is reduced, so J-Lay Tower perform better if positioned midship instead of astern and a moonpool is an advantage too. o If the vessel can weathervane while laying, its motions are drastically reduced: This is possible in J-Lay if the Tower can tilt but not in S-Lay.
Once these main causes of the fatigue have been minimised, the resistance to fatigue depends intimately on the performance of the weld. This is where the EPIC Contractor can make a difference by proposing high quality welding during installation.
Generalities on SCR welding The main challenge in any SCR design remains the fatigue performance of the weld. SCR in deep water development can be subject to severe environmental loading and the fatigue performance is often limited by the girth weld.
Typical welding in J-Lay Tower
Grinding the weld cap improve fatigue performance
The prerequisites for fabrication of SCR welds include: •
•
•
Close control of pipe end tolerances and joint misalignment. Typical SCRs may require joint hi / lo to be controlled to a maximum tolerance of ± 0.5mm. In order to achieve this limit, it may be required to perform counter boring of the pipe ends, together with pipe end sorting and ID grouping. High integrity welding procedures. Close control of welding parameters is required to ensure freedom from lack of fusion defects and to provide satisfactory internal root and external cap profiles. Typical SCR specifications place stringent requirements on allowable welding defects. For high fatigue performance, it may also be necessary to flush grind the weld caps. This can achieve a significant improvement in fatigue life in riser pipelines where fatigue is limited by crack initiation at the cap weld toe.
Installation of carbon steel SCR’s by the reel-lay method has been demonstrated to be cost effective. A significant benefit for SCR fabrication is that the majority of the girth welds can be fabricated and inspected on-shore in a controlled environment making it easier to ensure that high weld integrity is achieved. In recent years, Subsea 7 has installed two reeled carbon steel riser projects namely Blind Faith and BC10. The former comprised two off SCR’s with dimensions of 7.625” x 25.4mm and 7.625” x 25.6mm in API 5L x 60, with a total length 2.6km. The latter comprised 7 off risers, with a total length of 21km in pipe with dimensions of 6” x 15.9mm and 12” x 19.1mm in API 5L x 60 (Please refer to Track Record). For both projects, the mechanised hot wire Pulse Gas Tungstene Arc Welding (PGTAW) welding process was used for the fabrication for the mainline girth welds. This process gave good assurance of weld integrity together with excellent mechanical properties. Please see Ref /6/ OTC 21655.
Qualification of Mechanically Bonded Clad Pipe for Reeled Lay Subsequently Subsea 7 has performed a development programme to qualify a welding solution for reelable clad pipe. Up until recently, the reel-lay installation of clad pipe has been impeded by the lack of fatigue performance data. The objective of this programme was to develop and qualify a welding procedure for clad pipe suitable for SCR service and to demonstrate that the required fatigue life could be achieved in the reeled condition. A weld solution was developed based on the mechanised Hot Wire PGTAW process using Alloy 625 filler wire.
Mechanised PGTAW equipment in operation and typical weld macrosection in clad pipe
A clad pipe weld procedure was qualified in accordance with the requirements of DNV OS F101 – 2007 and typical industry SCR specifications. Automatic Ultrasonic Testing (AUT) was selected as the primary Non-Destructive Examination (NDE) method. A validation of the AUT inspection procedure was performed to ensure that planar flaws of concern could be reliably detected and sized. Clad pipe strings compromising representative butt welds were then manufactured and inspected. These were subjected to a full scale simulated reeling and installation procedure which was representative for pipeline installation by the Seven Oceans reel lay vessel. These butt welds were subsequently subject to full scale fatigue testing using the high frequency resonance testing technique. The fatigue performance exceeded expectations, with most test samples failing in the parent material with fatigue levels close to the Class B mean curve. Although the mechanised PGTAW process is capable of producing high integrity girth welds, the welding productivity is limited. For this reason Subsea 7 has developed the mechanised Gas Metal Arc Welding (GMAW) process to achieve higher production rates whilst maintaining acceptable weld quality for SCR service.
Mechanised PGMAW equipment in operation
A critical feature of the developed welding solution is the use of the CMT (cold metal transfer) process for root welding. This is an advanced GMAW technique which allows the weld root to be deposited very precisely with minimum heat input, giving good control of the weld root quality and profile, as can be seen in pictures below.
Typical PGMAW girth weld samples in clad pipe showing CMT weld roots
The subsequent weld passes are performed with the PGMAW process which gives good weld fusion characteristics and mechanical properties. This welding solution has been developed and qualified for both carbon steel and clad / lined pipe. Early next year (2013) will see the first implementation of this welding solution for riser fabrication, namely the Guara and Lula projects in Brazil. A key factor for the reel-lay installation of mechanically lined pipe is the avoidance of wrinkling damage to the liner material. This is successfully accomplished by the use of internal pressurisation. Subsea 7 has performed a qualification programme in accordance with DNV recommended practice for new technology qualification RP-A203 (DNV-RP-A203, 2001). The tests were witnessed by DNV which also carried-out an independent review of the results and awarded the “fit-for-service” status to the technology. Full scale testing, supported by FE modelling demonstrated freedom from liner damage and a capacity to achieve the fatigue performance requirements for the Guara Lula project (Class F) in the reeled condition. Please see Ref /7/ OTC 23096.
Prefabrication of SCR onshore As previously explained, the highest performance welds can be achieved during onshore prefabrication of SCRs. Stalks of SCR are then assembled onto another and spooled onto a reel ship. The fabrication and spooling of a typical pipeline/SCR will be illustrated thereafter by Subsea 7’s state of the art spool base in Vigra, Norway.
Vigra Spool Base in Norway: Ariel View and Automated Welding Station
The fully automatic pipe handling system assembles the pipeline sections to be welded at the automated welding stations. The welding, AUT and field joint coatings are performed in sequence in the fabrication yard making the process very efficient with the highest quality welding. The SCR sections can be fabricated in stalk lengths of approximately 1,000 m. The stalk length will vary depending on the facility. When the stalks are fabricated, they are stacked-up before the spooling as shown below.
Fabricated Pipeline/SCR Stalks waiting to be spooled onto Seven Navica
The final step in the fabrication process is to spool the stalks onto the reel of the reel-lay vessel, which is shown above. The fabricated stalks are spooled onto the reel-lay vessel with certain back tension to avoid buckling during reeling. Once the first stalk is spooled in, the second stalk is welded on to the first stalk and the spooling continues. Subsea 7 has similar spool bases in Angola, Brazil and USA:
Subsea7 Spool Bases Across the Globe
Deepwater Installation Methods SCRs can be installed by all three methods of pipe-lay: -
S-Lay J-Lay Reeled Lay.
S-lay was the 1st method historically used to lay rigid pipe and is still employed in shallower waters. Soon after, the J-Lay method emerged with water depth increasing. Subsea 7 installed the first ever metallurgically bonded clad SCR in Bonga field using the J-Lay method and subsequently for Erha field development. Subsea 7 has also installed many SCRs by Reeled Lay such as; Roncador (P-36) in Brazil and Blind Faith in the Gulf of Mexico. Subsea7 has successfully completed more than 20 projects involving the installation of SCRs. Below is a summary of the deepest ones in recent years: Subsea7 Deepwater Track Record Max OD
WT
Config
Max Top Tension
Clad Pipe
/ Reel lay
10”
20.6mm
Free Hanging SCR
150Te
No
Seven Polaris
J-Lay
16”
29mm
Free Hanging SCR
350Te
Yes
2006
Seven Polaris
J-Lay
22”
35mm
Free Hanging SCR
387Te
Yes
US GoM
2007
Seven Oceans
Reel Lay
7.5”
25.4mm
Free Hanging SCR
~300Te
No
2,000m
Brazil
2009
Seven Oceans
Reel Lay
12”
19mm
Lazy Wave SCR
240Te
No
Shell
1,200m
Malaysia
Ongoing
Sapura 3000
J-Lay
18”
30.7mm
Free Hanging SCR
300Te
No
GuaraLula
Petrobras
2,100m
Brazil
Ongoing
Seven Oceans
Reel Lay
9.5”
21.1mm
BSR
~275Te
Yes (*)
Erha North Phase 2
ExxonMobil
1,200m
Nigeria
Ongoing
Seven Borealis
J-Lay
12”
25.4mm
Free Hanging SCR
~270Te
Yes
Project
Company
Water Depth
Country
Date
Vessel
Roncador
Petrobras
1,360m
Brazil
2000
Seven Navica
Bonga
Shell
1,150m
Nigeria
2005
Erha
ExxonMobil
1,200m
Nigeria
Blind Faith
Chevron
2,150m
BC-10
Shell
Gumusut
Method J-Lay
(*) Mechanically Bonded
Deepwater Installation Spread Deepwater installation of SCRs require vessels that provide the best stability offshore, large top tension capability and can efficiently handle large quantities of rigid pipe. Two state-of-the-art vessels are used by Subsea 7 to install deepwater SCRs; Seven Oceans to install by Reeled-Lay and Seven Borealis by J-Lay and S-Lay. Subsea 7’s multipurpose construction Seven Seas can also install SCRs by J-Lay. Subsea 7 has additional vessels that are capable of the installation of SCRs such as Seven Navica (Reel Lay) and Seven Polaris (S-lay). The Sapura 3000 is operated by the SapuraAcergy joint venture and is capable of both S-lay and J-lay operations.
The Seven Borealis is a new build vessel and is due to be commissioned by November 2012. It has capabilities including; J-Lay pipelay, S-Lay pipelay and heavy lift. The vessel has been designed for deepwater and ultra-deepwater applications in the world’s harshest environments. The J-Lay tower onboard the Seven Borealis is a 2nd generation design which improved efficiency and versatility compared to Acergy Polaris. Seven Borealis Principle Particulars
Vessel Size
Length; 182m and Beam; 46m
J-Lay Capabilities
937Te top tension and up to 24” pipe
S-Lay Capabilities
600Te top tension and up to 46” pipe
Pipe Storage
2,800Te
Crane Capacity
5,000Te
Seven Borealis
The large top tension and pipe size capabilities of the Seven Borealis J-Lay tower mean that even the largest SCR’s can be installed. The tower can also “gimble” up to 15 degrees (tilt compared to vertical in any direction relative to vessel) so Seven Borealis can freely change her heading during J-Lay: this reduces drastically the vessel motion and hence the fatigue damage during installation. The Sapura 3000 is a pipelay and heavy lift vessel fitted with a 3000te mast crane and an Slay firing line. Recently, she was upgraded with the addition of a J-lay tower. With this functionality, the Sapura 3000 is capable of the installation of all types of SCRs.
Sapura 3000 Principle Particulars
Vessel Size
Length; 151m and Beam; 38m
J-Lay Capabilities
400Te top tension and up to 20” pipe
S-Lay Capabilities
240Te top tension and up to 60” pipe
Crane Capacity
3,000Te
Sapura 3000
The Seven Polaris (previously Acergy Polaris and Seaway Polaris) has previously installed many SCR’s, as described in the section above. Her J-lay tower is now mobilised on Sapura 3000. The Seven Oceans is a pipelay vessel complete with a sophisticated reeled pipelay system capable of both rigid and flexible pipelay. With a top tension of 400Te, the Seven Oceans is capable of installing large SCR’s up to 16”. The lay system includes a 450te A&R winch that can be used for the SCR transfer operations. Seven Oceans Principle Particulars
Vessel Size
Length; 157.3m and Beam; 28.4m
Reel-Lay Capabilities
3500Te reel
Pipe Sizes
6” – 16”
Crane Capacity
350Te
Seven Oceans
The Seven Seas is a construction and flexlay vessel, complete with a J-lay tower for rigid pipelay. A sister ship of the Seven Oceans, the Seven Seas J-Lay tower lays through the moonpool effectively increasing the maximum sea state for pipelay activities. The vessel has a maximum top tension of 400Te for rigid pipelay.
Seven Seas
SCR Hook-Up Offshore Installation challenges not only reside in laying the pipe but also connecting it to the floating facility. FPSOs are usually delivered with a schedule constraint and a very congested deck. The EPIC Contractor can add value to the field development by de-coupling SCR Hook-Up operations from the pipelay itself: In order to avoid the risk of having an installation vessel waiting for the FPSO to be moored to the field, risers can be preinstalled prior to the FPSO delivery and then recovered from seabed and hooked-up by a smaller vessel once the FPSO is moored. Wet storing SCR brings its own challenges: First, SCRs must be laid down under the FPSO theoretical position: either in separate curve corridors or crossing on top of one another. It is important to accurately determine these wet storage routes with respect to first oil risers, minimum bend radius of products, crossing protection and stability of the products on the seabed, always in a very congested area as many risers converge to the same point. Subsea7 has successfully completed this operation for the Shell BC-10 project in Brazil (see further) and is going to undertake it again for Shell Gumusut in Malaysia next year.
Gumusut SCR Wetstorage Pattern
Typical Suction Anchor for SCR Initiation
In order to contain the risers near the touch down point (TDP), SCRs may be anchored to suction piles on the sea-floor both in temporary and in-place position, which add complexity to the installation. The top end must be protected during the temporary laydown: the flexjoint is immobilised in rotation relative to the pipe by 2 metal half-shells so the elastomer is not crushed by hydrostatic pressure and thermal shrinkage in deepwater and not overbent during the laydown/recovery. This add-on must be removed before hang-off at surface.
Typical Laydown Tool Mounted on Flexjoint
The key points of the deepwater SCR recovery to surface are: • High pulling loads, especially if the SCR is flooded (up to 450Te is field proven and developments for up to 600Te are currently envisaged) • Large angle of pulling (usually between 12° and 20° from vertical at top in place, which prevents from using a crane due to offlead restrictions) • Congestion subsea : o Interference with mooring lines. o Cross-haul under FPSO hull; if the properties of the SCR do not allow them to be curved on the seabed. • FPSO Deck congestion: o Little to no footprint allocated to the Riser Pull-in Equipment onboard the FPSO: the entire spread may have to be located on a cantilevered platform and demobilised after use. o No assistance from the FPSO crane: Additional winches to the main pulling system required to guide the flexjoint in its receptacle. o Receptacle below seawater level even when FPSO is fully de-ballasted (requiring diving intervention). Please see Ref /4/ MOSS 054.
Erha Riser Pull In System Arrangement
For Erha project in Nigeria, Subsea7 very successfully used a purpose built 400Te chain jack system that was designed entirely to cantilever over the side of the FPSO hull. It slid from one slot to the other along the riser porch and could operate independently from any support from the FPSO. It was split into modules of less than 30Te each that were able to be lifted by a light construction vessel for demobilisation. It could have enabled relocation to opposite side of the FPSO, too.
BC-10 Lazy Wave SCR Experience The Parque das Conchas (BC-10) field is located off the coast of Brazil in the Campos Basin in water depths from 1190 m to 1940 m. During Phase 1 of the project, the Ostra, Abalone and Argonauta B-West fields were tied-back via Steel Lazy Wave Risers (SLWR) to the turret-moored FPSO in approximately 1,800m water depth as shown below.
BC10 Field Layout
Shell developed the SLWR concept to improve fatigue performance and to reduce payload on the FPSO turret in ultra deep water. Buoyancy elements were attached to the risers in the sagbend region near the TDP to achieve an SLWR configuration providing better compliance of the riser to FPSO motion responses in harsh environmental conditions, thereby improving fatigue life. A 23 m long flexjoint assembly comprised of forgings is provided at the top end.
BC-10 Buoyancy Module and Flexjoint installation on Seven Oceans
Installation of the risers was performed using Subsea 7’s reel lay vessel Seven Oceans. In principle, the flow lines were initiated from the pipeline end terminations (PLETs) and laid
towards the FPSO. The initial plan was to pre-install the risers on the seafloor prior to the FPSO arriving on site. However, only half of the risers were pre-installed with the remaining risers a direct handover to the FPSO.
BC-10 Ostra SCR spooling onto Seven Oceans Reel at Ubu Spool Base
The key steps for the installation of the SLWR and flow line are: 1. 2. 3. 4. 5. 6.
Spooling of the flow line and riser at Ubu spool base Initiation of the PLET Installation of buoyancy modules Installation of VIV fairings Welding of the Flex-joint Riser transfer to FPSO
BC-10 Ostra SCR PLET Initiation under Seven Oceans Lay Spread
Critical activities were: • • •
Buoyancy modules installation, because of their heavy weight and large dimensions. This was completed successfully without any incident. Flexjoint weld. This was completed successfully with the highest quality. The pre-installation configuration of the risers on the sea floor was extremely complex due to both installation and recovery requirements. Subsea 7 performed detailed riser and umbilical lay and recovery analyses, Please see Ref /5/.
The entire pipe lay campaign was completed in nine months including time for transits, mobilizations for pipe spooling, loading equipment, deck reconfiguration and re-fuelling, plus delays due to weather. Delays due to weather were mitigated by performing extensive upfront analysis as well as specific detailed analysis based on actual site observations and short-term weather forecasting. For some of the flow line and risers, the lines were installed full of water to improve vessel weather performance. The Seven Oceans was capable of installing all lines in the flooded conditions with no special modifications. Please see Ref /8/ OTC 20605
SCR Transfer from Seven Oceans to BC-10 FPSO in Brazil
Conclusions Deepwater SCR installation presents many challenges around the selection of the configuration, material selection, fabrication and installation methodology which when they are all well addressed will ensure the success of the projects. It requires a close cooperation between the design and the installation teams and a careful planning of the offshore operations: SCR welds, being one of the weakest link of the assembly, have attracted a substantial R&D effort from Subsea 7 that has been performed in its extensive welding R&D facilities in Glasgow. A very high quality SCR welding process was achieved, especially for clad SCR. Subsea 7 vessels offer the possibility to install all types of SCR by the best appropriate method.
Acknowledgement The authors would like to thank Subsea 7 colleagues for their support during the assembly of this paper.
Bibliography /1/ Duquesne, V & Tenet, C 2006, ‘Steel Catenary Riser Installation on FPSO’, Proceedings of the Eighteenth D.O.T Conference, Deep Offshore Technology, Houston, Texas /2/ Hansen, V, Sodahl, N, Aamlid, O & Jenkins, P 2001, ’Reeling and J-lay Installation of SCR’s on Roncador Field’, Proceedings of the 2001 Offshore Technology Conference, Houston, Texas /3/ Barthnel, K, Macklin, J & Weustink, O 2002, ‘Madison-Marshall Hookup to Hoover Diana DDCV: The Choreography of the SCR Installation’, Offshore, vol. 62, no. 12, pp. 52. /4/ Quintin, H & Abélanet, M 2008, ‘Design and Installation of Steel Catenary Risers in Deep to Ultra Deep Water’, MOSS 054, Proceedings of the Marine Operations Specialty Symposium 2008 /5/ Sarkar, T, Tahirovic, J & Sriskandarajah, T 2009, ‘Modelling of Steel Catenary Risers(SCRs) Installation by Pre-Abandonment Recovery & Transfer Method’, Proceedings of the 2009 International Conference on Floating Structures for Deepwater Operations, Glasgow, Scotland /6/ Jones, R, Karunakaran, D, Wang, H & Mair, J 2011, ’Reeled Clad SCR Weld Fatigue Qualification’, OTC 21655, Proceedings of the 2011 Offshore Technology Conference, Houston, Texas /7/ Toguyeni, G. & Banse, J 2012, ‘Mechanically lined pipe: Installation by reel lay’ – Paper OTC 23096, Proceedings of the 2012 Offshore Technology Conference, Houston, 30 April 3 May, 2012 /8/ Sarkar, T, Benirschke , A & Thomas, B 2010, ‘Parque das Conchas (BC-10) Steel Lazy Wave Riser Installation: Pre-Abandonment, Recovery and Transfer Challenges’, OTC 20605, Proceedings of the 2010 Offshore Technology Conference, Houston, Texas,
