OFFSHORE ENERGY Turret Design and Operational Integrity Andrew Newport, Technology Director, SBM Offshore
Turret Design and Operational Integrity 1 2 3 Overview of turret mooring systems Design and Operational integrity Overview of the Stones turret mooring 19.09.2017 2
Weathervaning systems
Turret System Components 19.09.2017 4
Internal versus External 19.09.2017 5
Permanent versus Disconnectable 19.09.2017 6
16 floating units in the fleet USA Brazil Equatorial Guinea Angola Asia 19.09.2017 7
Turnkey turrets 19.09.2017 8
Turret Design and Operational Integrity 1 2 3 Overview of turret mooring systems Design and Operational integrity Mooring legs and Out of Plane (OPB) bending Weathervaning system Swivels Overview of the Stones turret mooring 19.09.2017 9
Mooring legs 19.09.2017 10
Traditional chain connectors
Anchor Leg Configuration 19.09.2017 12
Out of Plane Bending Fatigue T M A Interlink angle a int M B MA=-MB+Tsin( a total - a int )*4d 4d T a total Tension Angle Out of Plane Bending (OPB) fatigue was first identified in 2002 (Girasol Deep Water Buoy) 19.09.2017 13
OPB Guidance OTC-25779-MS Chain Out of Plane Bending (OPB) Joint Industry Project (JIP) Summary and Main Results Lucile Rampi, SBM Offshore, Fata Dewi, SBM Offshore, Pedro Vargas, Chevron OMAE2016-54195 Chain Out of Plane Bending (OPB) Joint Industry Project (JIP) Static Test Program and OPB Interlink Stiffness Lucile Rampi, SBM Offshore, Fata Dewi, SBM Offshore, Michel Francois, Bureau Veritas, Arnaud Gerthoffert, Bureau Veritas, Pedro Vargas, Chevron Energy Technology Co. OMAE2016-54198 Chain Out of Plane Bending (OPB) Joint Industry Project (JIP) FEA Results and Multiaxiality Study Results Lucile Rampi, SBM Offshore, Andre Bignonnet, Ab Consulting, Cedric Le Cunff, Principia, Francois Bourgin, Principia, Pedro Vargas, Chevron Energy Technology Co OMAE2016-54199 Chain Out of Plane Bending (OPB) Joint Industry Project (JIP) Fatigue Test Program Result and Methodology Lucile Rampi, SBM Offshore, Arnaud Gerthoffert, Bureau Veritas, Michel Francois, Bureau Veritas, Andre Bignonnet, Ab Consulting, Pedro Vargas, Chevron Energy Technology Co. 19.09.2017 14
Double articulated chain connector Roll Body Pitch Body Hawse Pipe Chain Long hawse pipe and low friction bushes ensures the connector rotates before the chain links bend significantly
Articulated Rod Connecting Arm (ARCA) 19.09.2017 16
Technology Readiness Level 4 19.09.2017 17
Turret Design and Operational Integrity 1 2 3 Overview of turret mooring systems Design and Operational integrity Mooring legs and Out of Plane (OPB) bending Weathervaning system Swivels Overview of the Stones turret mooring 19.09.2017 18
Load transfer between fixed turret and rotating vessel Single forged 3 race roller bearings are limited to approximate 10m diameter. This limits load capacity and riser count. 19.09.2017 19
Segmental Bearings Segmental bearings can be used on top mounted turrets and external turrets Available in diameters up to 21m, but with limited offshore experience 19.09.2017 20
3 race roller bearings are used in all main turret configurations External BMIT TMIT
Loads on the bearing Mooring and riser loads Inertia of the turret system Vessel deformations Bearing companion structure deformations 19.09.2017 22
Loads on the bearing Mooring loads, riser loads and inertia loads are all directly imposed on the bearing system 19.09.2017 23
Hull hogging and sagging ovalizes the deck around the moonpool 19.09.2017 24
Isolated from vessel deformations to avoid additional loads on rollers
Companion structure deformations must be limited Bearing support structure (Rotating part) Bearing Outer ring Inner & Outer bolts Rollers Inner ring Seals arrangements
Regular slamming loads on the bearing should be avoided
Bogie bearings provide a high capacity alternative to roller bearings Virtually no limit on riser number Virtually no limit on mooring loads Bogies and radial wheels are standard components Bogies and radial wheels are inspectable and replaceable
The bogie bearing system incorporates bogies and radial wheels TO TOPSIDE GANTRY BOGIES RADIAL WHEELS DECOUPLING BOGIE SUPPORT STRUCTURE Sea level
Lowering the turret cyclinder through the moonpool Bogies support axial loads Radial wheels support radial loads The bogie design is standard, and the number used is selected to accommodate the design loads (N+1) Dry access in turret for inspection and maintenance
The system provides dry access for inspection and maintenance
Stoppers gives a massive increase in load capacity for extreme events Gap only closed during extreme loads Lower stoppers then provide additional load path Lower stoppers limit uplift on the bogies SCHIEHALLION Mooring force ~ 2000T SKARV, PRELUDE, ICHTYS Mooring force > 5000T
Turret Design and Operational Integrity 1 2 3 Overview of turret mooring systems Design and Operational integrity Mooring legs and Out of Plane (OPB) bending Weathervaning system Swivels Overview of the Stones turret mooring 19.09.2017 33
Swivels transfer fluids, utilities, power and signals
A range of swivel types are required Fluid Swivels for oil, water and gas (Pipe Swivels) Fluid Swivels for oil, water and gas (Toroidal Swivels) Utility Swivels for transfer of chemicals, hydraulics, air/gas, firewater and vents) Electrical and Optical Swivels for the transfer of power and signals / information
Swivels are assembled into swivel stacks
Torodial fluid swivels are the principal component of most swivel stacks
Sealing concepts are fundamental to swivel design Isolation & primary seals form the Oil Barrier cavity The Oil Barrier is maintained at a higher pressure than the process fluid Secondary seals are used to back-up primary seals, and permit leak monitoring
Seal replacement method should minimize disruption to production SBM s approach is to preinstalled spare seals Seals can also be replaced in-situ using seal welding technology No impact on adjacent swivels Tools to aid seal changeout are provided with the swivel stack
Seals can be replaced in-situ
Turret Design and Operational Integrity 1 2 3 Overview of turret mooring systems Design and Operational integrity Overview of the Stones turret mooring 19.09.2017 41
The Stones fieldis located 200 miles (320 km) south of New Orleans
FPSO Turritella is an Suezmax conversion with 7000 t topsides
The novelty was concentrated in the turret mooring system Remains connected in winter storms Disconnectable to avoid hurricanes Installed in 2,900m water depth Buoy supports steel lazy wave risers (SLWR) 6000 t displacement buoy Buoy is a hybrid construction of steel and syntactic foam Heave compensation system provided to pull in the buoy Distributed locking system to connect and disconnect the buoy
Syntactic foam used to counter high water pressure on the buoy
A trial fit of the lower turret and buoy was carried out in the fabrication yard
A distributed locking system connects the buoy to the turret
A generic prototype was developed to reach TRL 4
The locking devices were installed in the lower turret prior to integration
Successful dynamic drop test of the buoy
Installation of the bogie bearing support
The first application of steel risers on a disconnectable mooring system
Summary Operational integrity is highly dependent upon the system design, particularly at component level Out of Plane (OPB) bending fatigue is now recognized and well understood, and chain connector design must account for this phenomenon Bearing design must account for all external loads, including future loads and the effects of the riser installation program. The bearing companion structure should be stiff enough to avoid excessive deflections of the bearing, and should isolate the bearing from deck strains A distributed bearing system such as a bogie bearing allows redundancy in design, and the ability to change out components offshore In the event of damage to a seal, quick seal change-out with minimum disruption to production is paramount
Thank you for your attention Andrew Newport Technology Director SBM Offshore 19.09.2017 54