paper 43 - opt 2015_bhi 9_2_15
TRANSCRIPT
OPT 2015 – February 25, 2015
John Grover
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Deepwater Pipelines – the latest developments using coiled tubingdown-lines for pre-commissioning and contingency dewatering
OPT 2015 – February 25, 2015
John Grover
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Presentation Contents
Recent advances using large bore coiled tubingas a down-line
What do we mean by pre-commissioning?
Why do we need a down-line?
Down-line types and comparison
Latest developments in coiled tubing down-lines
What governs down-line size and capacity?
Custom coiled tubing system design
Connecting to the pipeline
Blue-water marine challenges
Innovative WBC solution using coiled tubing
Why do we need wet buckle contingencysystems?
Using coiled tubing to partially dewater anddepressurise a deep water pipeline section
Summary and conclusions
OPT 2015 – February 25, 2015
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What do we mean by pre-commissioning?
CleaningFlooding Gauging System PressureTesting
Dewatering Conditioning Drying Inerting
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Why do we need a down-line?
Wet End to Wet End Pipeline Dry End to Dry End Pipeline
Dry End to Wet End Pipeline
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Down-line types and comparison?
3 ½” x 2,200m
2 3/8” x 2,200m
3 ½” x 2,000m
3 ½” x 1,800m
Coiled Tubing Composite Flexible Hose
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Down-line types and comparison?
Attribute Coiled Tubing Composite Down Line
Delivery Time Better – 8 to 9 months Worse – 12 to 18 months
Cost Better Worse – approx.. 2 x CT price
Deck Space Much Better Much Worse
Mobilisation Better – can move by roadMuch Worse – at 150 tonnes for reel
alone only by sea
ReliabilityBetter – over 100 subsea deployments
and millions of well deployments
Worse – some history of composite
down lines failing during test and
deployment
Contingency
Much Better – a spare coiled tubing
string and reel can be supplied quickly
and at low cost
Much Worse – cost of spare line and
reel approx.. 20 x that of CT with 12
month + delivery
Vessel Installation Better – heaviest lift approx. 41,000 KGWorse – heaviest lift approx.. 150
tonnes
Maximum Internal
Temperature
Better – can withstand 90°C typical of
air booster discharge
Worse – limited to 60°C hence
additional air cooling required
Size AvailabilityWorse – current design limited to 3 ½”
OD CT pipe
Better – we believe up to 6” ID
available
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What governs down-line size and capacity?
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What governs down-line size and capacity?
Line NPS 16”
Wall Thickness 20mm
Line Length 8KM
Water Depth at launcher 1500m
Water Depth at receiver 1500m
Water Temp at surface 28°C
Water Temp at Seabed 4°C
Average dewatering velocity required 0.3 m/sec Average
Free air delivery flow / pressure at
pipeline injection point to achieve
0.5m/sec
11,000 cfm @ 152 barg plus friction loss
through hose. See below
Down-line
Internal Diameter
Down-line
Length
Pressure Top of
Downline (barg)
Pressure Drop
(barg)
2” 2,200m 277barg 125barg
3” 2,200m 173barg 21barg
4” 2,200m 157barg 5barg
OPT 2015 – February 25, 2015
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Custom coiled tubing system design
1
2
3
4
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Custom coiled tubing system design
Capable of operating in water depths
up to 3000m
Designed for large diameter coiled
tubing of 2 7/8” or 3 ½”
DNV certified to allow offshore lifting
Road transportable in two loads
Standard basic components giving
easy access to spare parts and
trained mechanics / operators
Flexible frame to allow use on a wide
variety of vessels, either through a
moon pool or over the side
Subsea connection assembly installed
on deck then injector frame jacks out
overboard
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Connecting to the pipeline
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Blue-water deployment challenges
• The main issue is the impact of current onthe coiled tubing string and the vesselmovement, resulting from wave action,which can cause fatigue in the pipe string.
• Problem not present down-hole
• Each project modelled using softwarebased systems such as OrcaFlex™
• Custom bend stiffener deployed whererequired
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Why do we need wet buckle contingency systems?
• System to mitigate against the effects of a wet buckle
• A wet buckle is best defined as an unplanned event where thepipeline has been damaged and the integrity of the pipeline hasbeen lost
• The sea water enters the air filled pipeline and displaces the air
• Increased weight of the seawater in the pipeline may overloadthe tensioners on the lay vessel and cause the pipeline to bereleased to the seabed
• The lay vessel typically will not be able to recover the pipelineuntil the pipeline has been emptied of water and a suitableconnection point is installed on the pipeline.
• Significant project costs usually recovered through projectinsurance.
• Insurers are aware of such risks and often insist that a wetbuckle contingency system be available at short notice duringthe offshore pipe lay period.
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Wet buckle contingency for deep water pipelines
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Partial dewatering and depressurisation – step 1
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Partial dewatering and depressurisation – step 2
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Partial dewatering and depressurisation – step 3
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Partial dewatering and depressurisation – step 4
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Partial dewatering and depressurisation – step 5
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Partial dewatering and depressurisation – comparison
Key Issue Partial Dewatering Conventional Dewatering
Dewatering Time
Much Better – 2 days
including deployment &
recovery
Much Worse – 31days @ min
of 0.3m/sec
Deck Space
Much Better – a spread
designed for 0.1m/sec requires
approx. 880 m2 of deck space
Much Worse – a spread
designed for min 0.3m/sec
requires in excess of 3,300m2
Fuel UsageMuch Better – total of 25,600
litres
Much Worse – total of
7,300,000 litres
Equipment Cost
Significantly Better – even
excluding fuel 1/3 of the cost of
std. WBC.
Much Worse – excluding fuel
at least 3 x the cost of partial
dewatering.
Installation Vessel
Standby
Better – excluding flooding
vessel standby could be less
than 5 days
Worse – excluding flooding
standby could be 40 days
OPT 2015 – February 25, 2015
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Summary and conclusions
1. Down-lines play an important role in the pre-commissioning of deep waterpipelines
2. Coiled tubing should be considered as the preferred down-line system exceptwhere very large bore down-lines are required. Even then multiple coiledtubing down-lines can be considered as an alternative
3. Custom marine coiled tubing systems provide the flexibility for moon-pool orover-the-side deployment and are largely self-supporting once installed
4. Engineering and modelling is required prior to deploying coiled tubing in ablue-water environment
5. Coiled tubing down-lines today being deployed in Australia, Bulgaria, Norwayand Brazil
6. Deep, large bore gas pipelines require vast air compression systems todewater the line post any wet buckle event
7. A partial dewatering system offers a faster, lower cost alternative to a full wetbuckle contingency dewatering system, especially for pipelines not intendedfor hydrostatic pressure testing
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Thank you and any questions?