SUBSEA INSTALLATION WITHOUT A HEAVY LIFT VESSEL A STEP CHANGE IN - - PowerPoint PPT Presentation

Subsea Deployment Systems Ltd.

SUBSEA INSTALLATION WITHOUT A HEAVY LIFT VESSEL A STEP CHANGE IN SUBSEA INSTALLATION

Subsea Deployment Systems Ltd.

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PRODUCT

• An alternative to an HLV for the recovery of subsea structures
• Low cost
• Allows even the smallest crane vessel to recover large structures
• Operations largely independent of weather
• Safer than a conventional lift
• Schedule flexibility

Subsea Deployment Systems Ltd.

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MARKET

• Installation or decommissioning of subsea structures
• 100t to several 1000t
• Optimum range 200t to 1000t
• 80m to 3000m water depth
• Hostile environments

Subsea Deployment Systems Ltd.

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ECONOMICS

• SDS + AHT @ $50k/day compared to an HLV @$1m/day
• Minimal risk of weather delays
• Year round operation

+

VS

Subsea Deployment Systems Ltd.

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SAFETY AND ENVIRONMENT

• Low tech / fail safe
• Operations can be suspended at any time (no point of no return)
• Operations insensitive to weather
• Negligible dynamic loading
• Structures are not recovered to deck
• Reduced risk of catastrophic loss
• Fewer personnel
• Low carbon footprint

Subsea Deployment Systems Ltd.

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THE SDV MAIN COMPONENTS

CONTROL CHAIN CONTROL TOWER TOW CHAIN CLUMP WEIGHT CASTL E STRUCTUR E BUOYANCY MODULES FLOODABLE HULL BALLAST LOCKER CONTROL CHAIN CONTROL TOWER TOW CHAIN CLUMP WEIGHT CASTLE STRUCTURE BUOYANCY MODULES FLOODABLE HULL BALLAST LOCKER

Subsea Deployment Systems Ltd.

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SYSTEM VARIATIONS

Subsea Deployment Systems Ltd.

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LOAD OUT

• Lifted
• Float off
• Submersible barge
• Floating dock
• Dry dock
• SUBMERSIBLE BARGE

Subsea Deployment Systems Ltd.

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SURFACE TOW

• Shallow surface tow
• Flood tanks
• Insert tow chain clump weight
• Pay out tow wire

Subsea Deployment Systems Ltd.

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SUBMERGED TOW

• Adjust tow wire and

speed

• Slow down to lower the

system

• Pay out tow wire to

lower clump weight

Subsea Deployment Systems Ltd.

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LOWER STRUCTURE

• AHT disconnects the tow wire
• Lower control chains into the control chain towers
• Slew crane to create lead on control chains
• Pay out chain until the system is neutral

Subsea Deployment Systems Ltd.

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CONTROL CHAIN TOWERS

• Rotational control
• On‐bottom weight
• Lateral control
• Vertical control

Subsea Deployment Systems Ltd.

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DYNAMICS

• Response governed by the natural period of the system
• Typically the natural period of a >1000t system > 120s
• Increased weather window for set down
• Minimal dynamic loading on the surface crane and structure

Subsea Deployment Systems Ltd.

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INSTALLATION

• AHT manoeuvres the system to final

target

Subsea Deployment Systems Ltd.

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BALLASTING

• Lower system slowly on to target
• Pay out remaining control chain into

control chain towers

• Install ballast weight to balance the

payload weight

Subsea Deployment Systems Ltd.

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LIFT‐OFF

• WROV disconnects payload
• Deploy down lines and reconnect to the

control chains

• Recover the control chains until the

subsea deployment vessel starts rising

• Continue raising until well clear of subsea

assets

Subsea Deployment Systems Ltd.

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RETURN TO SHORE

• Recover control chains until clear of the

control chain towers

• AHT tows the subsea deployment vessel

back to shore

Subsea Deployment Systems Ltd.

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DYNAMICS

SDV CLOSE-UP (SHADOWS) VESSEL & SDV (SHADOWS) FULL (30x)

Subsea Deployment Systems Ltd.

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SEASTATE STATISTICS

• Subject to operational

windows and seasonal variations

Subsea Deployment Systems Ltd.

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INHERENT SAFETY

TOW WIRE FAILURE (10x)

• Total Loss Minimised – “Close To Neutral”
• Insensitive to weather
• No point of ‘no return’
• Rigging failure
• Buoyancy loss

Subsea Deployment Systems Ltd.

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Subsea Deployment Systems Ltd.

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POTENTIAL APPLICATIONS

DECOMMISSIONING

• Operation is fully reversible

for new structures

• Interfacing flexibility with

existing structures

• Minimal dynamic loading
• Existing structures recovered

without lifting to deck

• Large skip

INSTALLATION

• 100t to several 1000t

structures

• Water depth 80m – 3000m
• Hostile environments

Subsea Deployment Systems Ltd.

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ADVANTAGES

• Low CAPEX/OPEX
• Simple and robust technology
• Safe
• Suitable for deep water and harsh environments
• Heavy lift capacity
• Greater availability compared to HLV
• Potential for phased installation and early production
• Potential for fewer structures, tie‐ins and interfaces

Subsea Deployment Systems Ltd.

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HLV SUPPLY

• LIGHTER (<150t)
• Market is mainly over supplied
• Generally not suitable for deepwater / hostile locations
• MIDMARKET (150T – 400T)
• Most of the vessels have other primary functions
• Capacity drops significantly in deep water / hostile locations
• LARGER (400T+)
• Very limited availability
• Opportunities exist for alternative lifting solutions

Subsea Deployment Systems Ltd.

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STATUS

• UK patent was awarded September 2010.
• Outline designs and installation procedures have been developed

for the Gorgon and Shtokman developments.

• Detailed study performed for Apache for the installation of two

structures at Forties.

• Technical evaluation has been performed by a major installation

contractor resulting in an offer to buy the patent outright.

• SDS is seeking a partner to assist in bringing the system to market.

Subsea Deployment Systems Ltd.