Monitoring slugging in subsea pipeline spanspipeline spansSPIM‐May 2013
Agenda
Introducing PulsegTypes of SpansWhy Monitor?Why Monitor?Typical System LayoutTrack RecordCase StudiesQuestions
2
Introducing Pulse
Established in 1998 as part of 2H pOffshore
Independent company since 2010
More than 500 subsea monitoring systems deployed worldwidesystems deployed worldwide
Offices in UK, US, Brazil and Singapore
An Acteon company 3
An ACTEON company
Types of spans
Free spansUnsupported section of subsea pipelineUnsupported section of subsea pipelineCaused by:
Pipeline profile does not conform to seabed geometrylocal sea bed mo ementlocal sea bed movement
U UU U
Onset of scour Tunnel erosion Lee-wake erosion Equilibrium stage
D
U
D e
eS
U
D D
e Soil
W1 W2 Potential fatigue damage to pipelineVortex induced vibration (VIV)Flow induced vibration (FIV)
Pipeline sleepersMethod of preventing lateral buckling on pipeline
Flow induced vibration (FIV)
However‐ can cause issues due to slugging6
Why Monitor?
•Improving decision making and scheduling
•Controlling hazards
making and scheduling
Enhance operational
Improve operational efficiency
Asset life
Controlling hazards to prevent pipeline failure •Provides evidence to
support Field Life E t ioperational
safety extension
To quantify the unknown
Extension
Proactive integrity
management
Design improvements
Calibrate the model• Continuous tracking
of fatigue to R d i i iimprovements
for future facilities
gdemonstrate “fitness for service”
•Reducing conservatism in analysis models
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•Improved understanding of materials and system functionality
Typical System Layout
Current Meter
Standalone Data LoggersLoggers
8
Free span monitoring system:Data loggerData logger
Standalone data logger monitoring systemTri axial accelerationTri plane angular rateExternal hydrostatic pressure sensor (for direct changes in water depth)The following parameters can be derived:
Linear displacementA l ti d t tiAcceleration due to motionAverage Inclination
Typical battery life of 3 months at 10hz intermittent samplingTypical battery life of 3 months at 10hz intermittent sampling
9
Free span monitoring system:Current meter
Current Meter
Current meter
Measures the speed and direction of ocean currents
Horizontal
direction of ocean currents using the principle of “Doppler shift”.
Upper
Battery Operated20‐30min recording per hour
Lower
2D 3D10
Interfaces
ROV/Diver deployable/ p ySeabed framesMagnetic InterfacesMagnetic Interfaces
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Interfaces:Rapidly deployable ROV clampRapidly deployable ROV clamp
Quick and easy to install using a y gstandard ROVLight weight ‐made from advancedLight weight made from advanced polymers ‐ does not corrode like metal holdersmetal holdersControlled clamping force – fit for pipe insulationpipe insulationCan be used on a range of pipe di tdiametersCan be used to retrofit sensor systems onto existing pipelines
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Operating principles
Single point ROV grab bars to operate clampAdapter developed to suit a range of ROVs ensuring any ROV can install clampTakes responsibility off the ROV in terms of resulting clamping force
Springs with adjustable pre load Stroke limit plates which effect the closed clamp stroke
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Operating principles
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Operating Principles
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Free span monitoring:Relevant ExperienceRelevant Experience
Humber estuary pipeline (UK) –2005y p p ( )
N th S i li ib ti 2009North Sea pipeline span vibration‐ 2009
Pipeline bundle tow out & span monitoring (Malaysia) ‐ 20092009
Gas pipeline span monitoring (Trinidad) – 2010
Gas pipeline span monitoring (Australia) – 2012‐13 16
Case StudyHumber Estuary PipelineHumber Estuary PipelineDetails: Monitoring of pipeline free
span in a river estuaryspan in a river estuaryIssue:
Client wanted to determine the flow velocities and directions that are incident upon the exposed section of pipep pWanted to establish whether the pipeline is experiencing VIV and potential fatigue affectspotential fatigue affects
System deployed:2 x INTEGRIpod SMp
2 x current meters
OutcomeNo evidence of VIV was found to be present in either the cross‐flow or in‐line direction 17
Humber Estuary PipelineData Analysis:Data Analysis:
32
x 10 -3
cc.
LO G G E R N O . T 14 - P E R IO D N O . 1737
0 1 2 3 4 5 6 7 8 9 100
1
2
3
2*|F
FT| o
f x-a
cc.
0 0 .5 1 1.5 2 2.50
1
2*|F
FT|w
of x
-a
2x 10 -3
y-ac
c.
0 1 2 3 4 5 6 7 8 9 10
1
2
3
2*|F
FT| o
f y-a
cc.
0 0 .5 1 1.5 2 2.50
1
2*|F
FT|w
of
1
2x 10 -3
w o
f z-a
cc.
0 1 2 3 4 5 6 7 8 9 100
2
frequency [Hz] 0 0.5 1 1.5 2 2.502*
|FFT
|w
frequenc y [H z ]
Acceleration Frequency Spectra for the Time Period Spanning the Maximum Current Event
Acceleration [FFT] Spectrum of Cylindrical Pipe Experiencing VIV
Typical VIV Spectrum Data monitored
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Case StudyPipeline Bundle Tow & Free SpanPipeline Bundle Tow & Free Span
Details: Monitoring of a pipeline bundle for response to towing and in service operations
Issue:Client required confirmation of the structural response and fatigue lifep gPart of design verification process
S l tiSolution:18 x ROV deployable/ retrievable INTEGRIpod SM
Continuous data loggingContinuous data logging
Outcome:Fatigue damage accumulated during tow outFatigue damage accumulated during tow outResponse found to be within limits 19
Pipeline Bundle Tow & Free SpanData Analysis:Data Analysis:
Fatigue damage g gwas accumulated during tow outgResponse was found to be withinfound to be within limitsProved analysisProved analysis model was fairly accurateaccurate
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Case StudyPipeline Span Monitoring‐ Trinidad & TobagoPipeline Span Monitoring‐ Trinidad & TobagoDetails: Monitoring 6 spans on a gas pipeline
i i id d & bin Trinidad & TobagoIssue:
Client wanted to determine:Span natural frequencies;Estimate pipeline span damping coefficients f dfrom measured response.
Solution:2 x INTEGRIpod SM to monitor vibration2 x INTEGRIpod SM to monitor vibration2 x diver deployable holders INTEGRIpod SM
Outcome:Movement induced on pipeline (ram)Data gathered allowed span dampening coefficient to be estimatedcoefficient to be estimated.
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Pipeline Span MonitoringData Analysis:Data Analysis:
For each span, it is observed that the span response p , p pfrequency identified during each of the strikes is consistent.
0.04
0.06q y p g @ gg
Y AccelerationResponse of Sigle DOF
0
0.02
atio
n(m
/s2)
0 04
-0.02
Acc
eler
a
0 5 10 15-0.06
-0.04
Time(sec)
Filtered Acceleration Response from INTEGRIpod vs Analytical Response using Estimated Damping Ratio for Span 435
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Thank YouThank Youwww.pulse‐monitoring.com
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