safe practice for vessel positioning with mooring analysis(orcaflex)

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VEDAM DESIGN & TECHNICAL CONSULTANCY PVT. LTD.

504-506, Acropolis, Military Road, Marol, Andheri (E), Mumbai-59, INDIA

+91-22-67109192 , +91-22- 67257237 [email protected], www.vedamindia.com

Design & Technology Center


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Challenges in present Station Keeping

Mooring Analysis A glance

Mooring Analysis Usage

Mooring Analysis Stages, Categories

Advantage with FUGRO-Vedam collaboration


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Complex platform and sub-sea infrastructure

Vessel positioning in close proximity to assets

Stringent safety requirement

Longer mooring durations

Operational requirement: gangway connections, helicopter operations

Vessel response under accidental damage of a line

Support vessels movement in close proximity to barge

Unconventional requirements: Connection to Jacket leg, DP buoys etc..

MOORING ANALYSIS IS A TOOL TO SIMULATE COMPLEX NATURE OF STATION KEEPING

TO ENSURE SAFETY AND REDUCE RISK DURING OFFSHORE OPERATION


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Field

Survey

Anchor

Pattern

Mooring

Analysis

CLIENT/MWS


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Motion analysis & determining RAO

Modelling of mooring pattern

Quasi-static Mooring Analysis (equilibrium

position)

Rule Check as per API/ISO/DNV

Standards


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Catenary shape & positioning of mooring

buoy

o Safe vertical distance from sub-sea

pipelines

o Limiting anchor loads

o Chain lengths for DP buoys

One line Damage analysis

o Limiting line tensions

o Limiting vessel excursions


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Transient analysis

o Vessel trajectory after breakage

of a line

o Maximum vessel offsets from

platform/assets.

Detailed Report and Anchor Pattern

with catenary diagrams,


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Derivation of exact catenary shapes

Correct estimation of distance between subsea structure and

mooring lines/anchors.

Mooring optimization to meet stringent safety requirement

Stabilisation of vessel motion, excursion

Clash Check

Usage of Damage Prevention Buoys

Derivation of limiting weather

Vessel Relocation Capability


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Deployed wire length

Initial tension in the wire

Load on Anchor

Location and size of DP buoys

Load on vessels mooring fittings

Safe navigation zone around

moored vessel


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Limiting Vessel excursion

Distance from pipe lines

Distance from floating bodies

Uneven distribution of spread

mooring

Support from Jacket Leg


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Effect of different directional

weather

Effect of extreme weather condition

Effect of one line damage condition

Limitation to excursion

Factor of Safety of anchor, line &

mooring fittings


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Limiting vessel roll & pitch motion

Limiting vessels heave motion for

Better habitability

Safe operation of gangway, crane etc

Safe platform repair work

Limiting vessel excursion

For position keeping for subsea

repair work


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Platform to barge safe distance

Anchor to pipe line distance

Across the pipe

Along the pipe

Mooring line to subsea pipe distance

Line to line distance in cross mooring

Distance from platform helideck or flare


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DP Buoy parameters for effective

lifting of mooring line

Location

Capacity or size

Buoy chain length

Catenary shape with effect of DP

buoys

Optimum usage of DP buoys


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Analysis with extreme weather condition

Derivation limiting weather condition for

safe working condition

Contingency plan beyond limiting weather


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Transient Analysis for relocating

the vessel

Line tension and catenary for

relocation operation

Weather condition for safe

relocation operation

safe practice for vessel positioning with mooring analysis(orcaflex)

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