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SUBSEA MANIFOLD DESIGN FOR PENDULOUSINSTALLATION METHOD IN ULTRA DEEP WATER
Mario L. P. G. RibeiroFMC CBV Subsea
Milton V. B. SeguraFMC CBV Subsea
José A. N. FerreiraPETROBRAS
Summary
• Subsea manifold main features and components
• Current manifold installation methods
• P52 manifold design
• Manifold structural analysis – FEA
• Hydrodynamic analysis
• Closing remarks
Subsea Manifold
• Functions:– Oil production
– Gas production
– Gas lift injection
– Water injection
• Objectives:– Optimize the subsea layout arrangement
– Reduce flowlines cost
– Reduce the quantity of risers connected to the platform
– Full production in advance
More than 20 Diverless Subsea ManifoldsManufactured in Brazil
1997 Albacora Phase 25 Unit. – 400m WD
2001 Namorado
1 Unit. - 200m WD
2004Marimbá Leste
1 Unit. – 715m WD
2004Viola
1 Unit. – 300m WD
2002 Bijupira & Salema5 Unit. – 800 WD 2006
Roncador Phase 2 –2 Manifolds on going
1998 Marlim
2 Unit. – 820m WD
1996 Albacora Phase 12 Unit. – 640m WD
2002 Roncador Phase 1
1 Unit. – 1,892m WD
Subsea Manifold – Main parts
MarimbáMarimbá Leste Leste ManifoldManifold
Structure with piping
Mud mat
Flowlines Hubs
ChokesCheckValves
Manual & Hydraulic Actuated Gate ValvesPig Diverter Valve
SCM
Flowmeter
Sensors
Manifold Installation Methods in Brazil
• Conventional procedures up to 1000 m WD
– Installation by cable
– Installation by drilling riser
• Non-conventional procedures over 1000 m WD
– Sheave Installation Method (Roncador Manifold Phase 1)
– Pendulous Installation Method (PIM)
with AHTS
with Crane Barge
To be used in the To be used in the next two P52 Manifoldsnext two P52 Manifolds
Conventional Installation Methods
• Work wire (w/o heave motioncompensation)
• Drilling Riser
AHTS
CraneBarge
Sheave Installation Method
• Offshore facilities:– SS rig: Provides heave motion
compensation
– AHTS 1: Lift the Manifold together with the SS rig
– AHTS 2: Orient the Manifold
AHTS 2 SS rig
AHTS 1
Roncador Manifold 11885m WD
P52 Manifold
• Dimensions: 16.5m (L) x 8.5m (W) x 5.2m (H)
• Weight in air: 280 tons
• WD installation: 1900m
• CG: 3.15m
P52 Manifold: Retrievable Modules
• Almost all components are retrievable
• One SCM per X-Tree, six in total
Top view
Gas Lift ModulePig Diverter Module
P52 Manifold: SCM
• Subsea Control Module (SCM)– Electrical components: vibrations and pressure rate
Manifold Structural Analysis – FEA
• Structure life– Construction steps: manufacture, assembly, integration test
– Road and sea transportation
– Installation
– Operation
• Loads– Permanent loads
– Operational loads
– Enviroments loads
• Dynamic Amplification
Factor (DAF): 2
Manifold Structural Analysis – Global Model
• Global model: AISC - LRFD checking
Lifting condition: AISC checking for axial load plus bending moment
Manifold Structural Analysis – Local Model
• Local model: von Mises checking – 60% of yield strength – 345Mpa
Lifting condition: von Mises stress distribution (MPa)
Hydrodynamic analysis
• Excessive Oscillations (initial instability)
Hydrodynamic effect
CG positionMunk effectDragLiftVortex shedding
Hydrodynamic analysis (Cont.)
• Increase hydrodynamic stability– additional buoyancy in the line installation (1)
– a hydrodynamic-adapted geometry, e.g., vertical or near vertical panels around equipment (2) and open holes in the mud mat (3)
– dead weight at the manifold mud mat
(1)
(2) (3)
Hydrodynamic analysis (Cont.)
• Mechanism to avoid initial instability
Mechanical fuse
PolyesterRope
Chain
BGL-1 (Crane Barge)
Closing Remarks
• For increasing the manifold reliability most of all components are retrievable;
• The assumed value for DAF (2) is enough to cover all the operational conditions;
• SCM supports installation loads;
• Counterweight is essential for avoid oscillations;
• Additional work for next manifold project is required in order to develop a “hydrodynamic structurehydrodynamic structure” to avoid the excessive oscillations during initial moments.
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