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

Pendulous Installation Method

• By pendulous – Barge and AHTS

FFUULLLL

SSCCAALLEE

TTEESSTT

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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