SAFE OFFSHORE VESSEL POSITIONING PRACTICE
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Veda m 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 SAFE OFFSHORE VESSEL POSITIONING PRACTICE ORCAFLEX WORKSHOP, 23 RD JUN 2012 IDEC, INTERCONTINENTAL, MUMBAI MOORING ANALYSIS
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SAFE OFFSHORE VESSEL POSITIONING PRACTICE. MOORING ANALYSIS. Orcaflex Workshop, 23 rd Jun 2012 IDEC, Intercontinental, Mumbai. AGENDA. Challenges in present Station Keeping Mooring Analysis … A glance Mooring Analysis – Usage Mooring Analysis – Stages, Categories - PowerPoint PPT Presentation
Transcript of SAFE OFFSHORE VESSEL POSITIONING PRACTICE
Vedam
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
SAFE OFFSHORE VESSEL POSITIONING PRACTICE
ORCAFLEX WORKSHOP, 23RD JUN 2012IDEC, INTERCONTINENTAL, MUMBAI
MOORING ANALYSIS
Design & Technology CenterVedam
Challenges in present Station Keeping
Mooring Analysis … A glance
Mooring Analysis – Usage
Mooring Analysis – Stages, Categories
Advantage with FUGRO-Vedam collaboration
AGENDA
Design & Technology CenterVedam
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 vessel’s 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
CHALLENGES IN PRESENT STATION KEEPING
Design & Technology CenterVedamGlobal Standards…
Design & Technology CenterVedamPOSITIONING SERVICE – WAY AHEAD…
Field Survey
Anchor Pattern
Mooring Analysis
CLIENT/MWS
Design & Technology CenterVedamMOORING ANALYSIS – AN OVERVIEW...
INPUT• Anchor Pattern• Environment• Location
MOORING ANALYSIS• RAO
CALCUATION• MOORING
ANALYSIS• CODE CHECK
OUTPUT• LINE TENSIONS• LIMITNG
ENVIRONMENT• DP BUOYS
Design & Technology CenterVedam
Motion analysis & determining RAO
Modelling of mooring pattern
Quasi-static Mooring Analysis (equilibrium
position)
Rule Check as per API/ISO/DNV
Standards
MOORING ANALYSIS – AN OVERVIEW...
Design & Technology CenterVedam Catenary shape & positioning of
mooring buoyo Safe vertical distance from sub-sea
pipelineso Limiting anchor loadso Chain lengths for DP buoys
One line Damage analysiso Limiting line tensionso Limiting vessel excursions
MOORING ANALYSIS … AN OVERVIEW
Design & Technology CenterVedam 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,
MOORING ANALYSIS … AN OVERVIEW
Design & Technology CenterVedam
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
USAGE OF MOORING ANALYSIS …
Design & Technology CenterVedam
Deployed wire length
Initial tension in the wire
Load on Anchor
Location and size of DP buoys
Load on vessel’s mooring fittings
Safe navigation zone around
moored vessel
MOORING ANALYSIS… CATENARY SHAPE
Design & Technology CenterVedam
Limiting Vessel excursion
Distance from pipe lines
Distance from floating bodies
Uneven distribution of spread
mooring
Support from Jacket Leg
MOORING ANALYSIS… COMPLEX FIELD LAYOUT
Design & Technology CenterVedam
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
MOORING ANALYSIS… STRINGENT SAFETY CRITERIA
Design & Technology CenterVedam
Limiting vessel roll & pitch motion
Limiting vessel’s 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
MOORING ANALYSIS… VESSEL STABILISATION
Design & Technology CenterVedam
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
MOORING ANALYSIS… CLASH CHECK
Design & Technology CenterVedam
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
MOORING ANALYSIS… USAGE OF DP BUOYS
Design & Technology CenterVedam
Analysis with extreme weather condition
Derivation limiting weather condition for
safe working condition
Contingency plan beyond limiting weather
MOORING ANALYSIS… LIMITING WEATHER
Design & Technology CenterVedam
Transient Analysis for relocating
the vessel
Line tension and catenary for
relocation operation
Weather condition for safe
relocation operation
MOORING ANALYSIS… RELOCATION ANALYSIS
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