structural monitoring of subsea pipelines and role in reducing
TRANSCRIPT
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Structural Monitoring of Subsea Pipelines and Role in Reducing Mitigation CostsSubsea Asia 2015 - Jakarta24th November 2015
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Agenda
• Introducing Pulse
• Pipeline Span Monitoring
• Slugging Monitoring
• FIV Monitoring
• Summary and Questions
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Introduction
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Monitoring Systems
software
Standalone logger Acoustic logger Dynamic curvature
sensors
Diver deployable holderfor mooring lines
ROV deployableholder
ROV deployablemagnetic holder
Field proven systems
Motion Strain SoftwareInterfaces
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Standalone Acoustic Hardwired Eexd
Data Loggers
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OverviewPipeline Integrity Monitoring Services
Slugging• Cyclic stress and inertial loading cause fatigue
Free Spans• Potential damage from VIV, FIV and slugging
• Increasing flow rates causing enhanced fatigue
FIV
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Pipeline Span Monitoring
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Pipeline Span Monitoring
• Span- unsupported areas of subsea pipeline
• Two types of span that can cause integrity concerns:– Natural spans (pipeline profile / geometry of seabed)– Pipeline sleepers (installed to control lateral displacement
and prevent pipeline buckling)
• Various potential fatigue damage– VIV (Vortex Induced Vibration), FIV (Flow Induced Vibration)
and slugging
Introduction
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Typical system layoutPipeline Span Monitoring
Current Meter
ROV Deployable Motion Logger
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Motion MonitoringPipeline Span Monitoring
Sensor Specifications*Tri Axial Accelerometers X,Y and ZRange [g] ± 2
Accuracy [m/s²] +/- 0.001
RMS Noise [m/s²] 0.0003
Resolution [m/s²] 0.000005
Tri Plane Angular Rate XZ, YZ and XY
Range [deg/s] ± 4
Accuracy [deg/s] +/-0.05
RMS Noise [deg/s] 0.008
Resolution [deg/s] 0.000001
Communication SpecificationSerial Communication Ports RS232
USB Port For Data Download
11*Based on INTEGRIpod Next Gen
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Mean Sea Level
Seabed = x/L =0
Rotary Table
Logger 56x/L= 0.000
Logger 55x/L= 0.112
Logger 54x/L= 0.160
Logger 53x/L= 0.208
Logger 52x/L= 0.257
Logger 51x/L= 0.305
Logger 50x/L= 1.000
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50
0.10.20.30.40.5
Frequency (Hz)
Acce
lera
tion
Ampl
itude
(m/s
2 )
Schiehallion Event 91 - Magnitude of Peak Response vs. Frequency
Acceleration
Amplitude (m/s2)Logger 56
x/L= 0.000
Logger 55x/L= 0.112
Logger 54x/L= 0.160
Logger 53x/L= 0.208
Logger 52x/L= 0.257
Logger 51x/L= 0.305
Logger 50x/L= 1.000
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50
0.10.20.30.40.5
Frequency (Hz)
Acce
lera
tion
Ampl
itude
(m/s
2 )
Schiehallion Event 91 - Magnitude of Peak Response vs. Frequency
Acceleration
Amplitude (m/s2)Logger 56
x/L= 0.000
Logger 55x/L= 0.112
Logger 54x/L= 0.160
Logger 53x/L= 0.208
Logger 52x/L= 0.257
Logger 51x/L= 0.305
Logger 50x/L= 1.000
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50
0.10.20.30.40.5
Frequency (Hz)
Acce
lera
tion
Ampl
itude
(m/s
2 )
Schiehallion Event 91 - Magnitude of Peak Response vs. Frequency
Acceleration
Amplitude (m/s2)
INTEGRIpods
Pipeline MonitoringVortex Induced Vibration
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Horizontal
Upper
Lower
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Pipeline Span Monitoring
Current monitoring
• Measures the speed and direction of ocean currents
• Battery Operated• 20-30min recording per hour
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Dynamic Curvature SensorPipeline Span Monitoring
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Sensor SpecificationsStick size 19mm OD – 506mm lengthWeight 1kg approx. in airDynamic Strain Measurement Accuracy 2µstrain RMSMeasurement Range ± 2,000µstrain
Note: Above specification for pipe Ø between 6” and 11.75”
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Sensor Interface Installation MethodsPipeline Span Monitoring
Motion
Strain
Current
Diver/ Topside ROV
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Recent projectsPipeline Span Monitoring
Pipeline bundle tow out & span monitoring - 2009
Pipeline bundle tow out & span monitoring - 2009
Gas pipeline span monitoring- 2010Gas pipeline span monitoring- 2010
Humber Estuary Pipeline- 2005Humber Estuary Pipeline- 2005
Gas pipeline span slugging monitoring- 2012
Gas pipeline span slugging monitoring- 2012
Gas pipeline span slugging monitoring- 2015
Gas pipeline span slugging monitoring- 2015
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Case Study: Humber Estuary Pipeline
• Monitoring pipeline free span in river estuary• Issue:
– Client wanted to determine the flow velocities and directions that are incident upon the exposed section of pipe
– Wanted to establish whether the pipeline is experiencing VIV and potential fatigue affects
• System– 2 x INTEGRIpod SM– 2 x current meters
Overview
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Case Study: Humber Estuary Pipeline
Outcome
0 1 2 3 4 5 6 7 8 9 100
1
2
3
2*|F
FT| o
f x-a
cc.
0 1 2 3 4 5 6 7 8 9 100
1
2
3
2*|F
FT| o
f y-a
cc.
frequency [Hz]
0 0.5 1 1.5 2 2.50
1
2x 10-3
2*|F
FT|w
of x
-acc
.
LO G G E R N O . T 14 - P E R IO D N O . 1737
0 0.5 1 1.5 2 2.50
1
2x 10-3
2*|F
FT|w
of y
-acc
.
0 0 .5 1 1.5 2 2.50
1
2x 10-3
2*|F
FT|w
of z
-acc
.
frequenc y [H z ]
• No evidence of VIV was found to be present in either the cross-flow or in-line direction
• Typical VIV Spectrum • Data monitored
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Case Study: Pipeline Bundle Tow
• Monitoring of a pipeline bundle for response to towing and in service operations
• Issue:– Client required confirmation of the
structural response and fatigue life– Part of design verification process
• System– 18 x INTEGRIpod SM– ROV deployable/ retrievable– Continuous logging
Overview
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Case Study: Pipeline Bundle Tow
Overview of Gravity Actuated Pipe
1.5km
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Case Study: Pipeline Bundle Tow
Outcome
• Fatigue damage was accumulated during tow out
• Response was found to be within limits
• Proved analysis model was fairly accurate
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Slugging Monitoring
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Slugging
• Occurs due to separation of liquids and gas in multiphase flow
• Causes cyclic loading leading to fatigue damage
• Certain infrastructure particularly susceptible to slugging:– Pipeline spans– Rigid jumpers– Sleeper crossings
• Can push structural utilizations above allowable limits
Introduction
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Case Study: Slugging Monitoring
• Monitoring of span on a gas flowline• Issue:
– Pipeline unsupported as it crosses subsea ridge– Vulnerable to fatigue from slugging & VIV
• System:– 6 x INTEGRIpod SM– 2 x INTEGRIstick– Record vertical & lateral
structural response– ROV installable/ retrievable
Overview
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High Speed Vibration Monitoring
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Flow Induced Vibration (FIV)
• Subsea vibration due to process excitation an increasing issue:– Higher flow rates– Increasing flexibility in pipework
• Particularly problematic on manifolds, jumpers and valves
• Issue may occur subsea with no obvious sign topsides
Introduction
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High speed vibration sensorsFIV Monitoring
Magnetic Sensor Lightweight Sensor
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Case Study: North Sea FIV Monitoring
• Monitoring a gas export pipeline in the North Sea
• Issue:– FIV inside pipe caused by trapped plug
tool– A vibration monitoring system was
requested for detecting the existence of such vibration
• System– High frequency monitoring system– Magnetic vibration sensor– 2 x INTEGRIpod SM High Speed
logging continuously
Overview
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Case Study: North Sea FIV Monitoring
• System found high frequency vibration present• Aided the operator to select a safe flow rate
Outcome
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0.01
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0.03
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0.07
0.08
0.09
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Frequency [Hz]
Am
plitud
e
X-Axis
Fast Fourier Transform (FFT) of the X-axis showing frequency of vibration
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Pipeline Monitoring
• Purpose of monitoring spans:• Understand the motion and its cause (wave, current,
VIV…)• Verify the design analysis and its operational integrity • Compare predicted motions to actual motions and calibrate
actual structural response• Verify effectiveness of VIV strakes
Summary
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Pipeline Monitoring
• Pipeline span doesn’t necessarily mean excessive motion and fatigue, understanding this can save on mitigation costs.
• Example from an ongoing project: • A client in GoM has for policy to mitigate all spans > 20m long• By monitoring their spans they expect to have to monitor less
spans and of longer length
Reducing Mitigation Costs
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Pulse Structural Monitoring LtdSteven GauthierM: +65 9722 [email protected]
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Thank you!