Acoustic Pipeline Leak Detection
Presented by Mark Wood
SALDS 2012 Houston TX
Ocean Sonics Ltd.
Design & Build Smart Hydrophones
Used for
•Ocean Science
•Environmental Monitoring
•Ocean Noise Measurement
•Sea Mammal Detection
•Pipeline Leak Detection
•Vessel Tracking
Data Presentation Software
Underwater Sound
Important Tool
Working in the Sea
Learning about the Ocean
Measuring the Health of the Sea
Visualization of Sounds
Always a Sub-plot!
Sounds can tell a story
Always a Sub-plot!
Ocean Pipelines
Safest way to transport energy
Pipelines age
Content is corrosive
Build-up
Damage
Storms
Anchors
Avalanche
Ocean Pipelines
Gulf of Mexico
Year
Damage Reports
2004
168
2005
542
2008
330
54,000 km of pipeline in 2007
2700 km of new pipeline/year avg.
GOM Pipeline Damage 2005
What is a leak?
Crack or split in pipe body
Stress, Construction, Movement
Spot Corrosion
Contents damage inside lining
Damaged Seal
Stress, Construction, Repair
Open Valve
Operator Error
Finding Leaks
Do we have a leak?
Hydrostatic Test
Unexplained pressure dip
How small is too small?
No agreement on this
Leak Sounds
Leak produces a ‘hiss’
Ultrasonic
Easier to detect visually
Leak Detection
Leak ‘Location’
Avoid False ‘Detects’
Physics of Leaks
Leak Types
Type
Liquid
Air
Ingress
1
3
Egress
2
4
Frequency
Increases with pressure & density
Decreases with leak cross sectional area
Intensity
Increases with pressure & density
Decreases with distance from the leak source
Physics of Leaks
Absorption Example
Assume a leak sound with average level of
140 dB re.1uPa
Range
10 kHz
100kHz
10 m
120 dB
120 dB
500 m
85 dB
70 dB
120 dB - Easy to detect
85dB - Fine in moderate noise
70 dB - Possible only in quiet environment
Pipeline Leak
Gulf of Mexico
Large Leak from Valve
ROV mounted
Ship
ROV
Smart Hydrophone
Pipeline Leak
ROV Thrusters & leak, no filtering
Pipeline Leak
ROV Thrusters & Leak - Filtered
Pipeline Leak
Gulf of Mexico
Diver
Gulf of Mexico
Pipe Repair after Storm
500 feet of water
Low visibility
Small leak prevented commissioning
Spent 5 weeks looking for leak
Cause: loose needle valve
Soundscape
Breathing regulator
Warm water circulator
Diver
Gulf of Mexico
Breathing
Diver
Gulf of Mexico
Leak Sound
Diver
Gulf of Mexico
Two Events
Large Submerged Pontoon
Gulf of Mexico
ROV Thrusters &
Leak
Unfiltered
Large Submerged Pontoon
Gulf of Mexico
Leak Signals
Progress
Challenges Addressed
Signal Quality
•80dB to 120dB dynamic range
•Lower noise floor to Sea State Zero
•Fully Calibrated - units in uPa
Simple Deployment
•Very Small, handheld, Single Cable
•Tactile Feedback
Progress
Challenges Addressed
Increase Reliability
•Tolerate ‘dirty power’
•Log all Survey Data Internally
Improve Event Detection
•Configurable Events based on frequency band &
energy
•Sends a message when event triggers
•Autonomous Operation
Progress
What’s left to do?
Develop Acoustic/Hydrodynamic Models
•Currently not well understood
•Account for sound channel effects, eg. depth,
sea bottom
Develop Feature Extraction Algorithms
•Filters that extract features unique to leaks
•Question of Funding still needs to be answered
Progress
Requirements
Discern False Detects
•Find Characteristics Specific to Leaks
•Develop Feature Extraction Algorithms
Modeling of Leak Hydrodynamics
Understand properties of Leaks Better
Leak Flow Dynamics
Modeling of Leak Hydrodynamics
Understand properties of Leaks Better
Environment Inside and Outside Pipe
Numerical model of pipe flow combined with leak flow
Other Leak Challenges
Pipe in Pipe
Is it possible to detect a leak?
Change construction to instrument pipe?
Buried Pipe?
Pipeline leaks
Passive Acoustics
Proven to be a powerful tool for finding pipeline leaks.
✴ Pipeline surveys using ROV or diver
✴ Deep water, up to 3500m depth
✴ Continuous pipeline health monitoring
✴ Max range function of leak sound intensity
Deeper understanding will improve detection quality
Thank You
Mark Wood
Ocean Sonics Ltd.
14 Nov. 2012 Nova Scotia