Monitoring slugging in subsea pipeline spanspipeline spansSPIM‐May 2013

Agenda

Introducing PulsegTypes of SpansWhy Monitor?Why Monitor?Typical System LayoutTrack RecordCase StudiesQuestions

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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

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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

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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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