Acoustic Pipeline Leak Detection

Presented by Mark Wood

SALDS 2012 Houston TX

Design & Build Smart HydrophonesUsed for

Data Presentation Software

•Ocean Science•Environmental Monitoring•Ocean Noise Measurement•Sea Mammal Detection•Pipeline Leak Detection•Vessel Tracking

Ocean Sonics Ltd.

Underwater SoundImportant ToolWorking in the Sea

Learning about the OceanMeasuring the Health of the Sea

Visualization of SoundsAlways a Sub-plot!

Sounds can tell a story Always a Sub-plot!

Ocean Pipelines

Safest way to transport energy

Pipelines ageContent is corrosive

Build-up

DamageStormsAnchors

Avalanche

Ocean PipelinesGulf of Mexico

54,000 km of pipeline in 20072700 km of new pipeline/year avg.

YearDamage Reports

2004 168

2005 542

2008 330

GOM Pipeline Damage 2005

What is a leak?

Crack or split in pipe bodyStress, Construction, Movement

Spot CorrosionContents damage inside lining

Damaged SealStress, Construction, Repair

Open ValveOperator Error

Finding LeaksDo we have a leak?

Hydrostatic TestUnexplained pressure dip

How small is too small?No agreement on this

Leak Sounds

Leak produces a ‘hiss’

UltrasonicEasier to detect visually

Leak Detection

Leak ‘Location’

Avoid False ‘Detects’

Physics of LeaksLeak Types

Frequency Increases with pressure & density

Decreases with leak cross sectional area

Intensity Increases with pressure & density

Decreases with distance from the leak source

Type Liquid Air

Ingress 1 3

Egress 2 4

Physics of LeaksAbsorption Example

Assume a leak sound with average level of 140 dB re.1uPa

120 dB - Easy to detect85dB - Fine in moderate noise

70 dB - Possible only in quiet environment

Range 10 kHz 100kHz

10 m 120 dB 120 dB

500 m 85 dB 70 dB

Pipeline LeakGulf of Mexico

Large Leak from ValveROV mounted

Ship

ROV

Smart Hydrophone

Pipeline LeakROV Thrusters & leak, no filtering

Pipeline LeakROV Thrusters & Leak - Filtered

Pipeline LeakGulf of Mexico

DiverGulf of Mexico

Pipe Repair after Storm500 feet of water

Low visibility

Small leak prevented commissioningSpent 5 weeks looking for leak

Cause: loose needle valve

SoundscapeBreathing regulator

Warm water circulator

DiverGulf of Mexico

Breathing

DiverGulf of Mexico

Leak Sound

DiverGulf of Mexico

Two Events

Large Submerged PontoonGulf of Mexico

ROV Thrusters & Leak

Unfiltered

Large Submerged PontoonGulf of Mexico

Leak Signals

ProgressChallenges 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

ProgressChallenges 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

ProgressWhat’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

ProgressRequirements

Discern False Detects

•Find Characteristics Specific to Leaks

•Develop Feature Extraction Algorithms

Modeling of Leak HydrodynamicsUnderstand properties of Leaks Better

Leak Flow Dynamics

Modeling of Leak HydrodynamicsUnderstand properties of Leaks Better

Environment Inside and Outside PipeNumerical model of pipe flow combined with leak flow

Other Leak ChallengesPipe in Pipe

Is it possible to detect a leak?Change construction to instrument pipe?

Buried Pipe?

Pipeline leaksPassive 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 YouMark Wood

Ocean Sonics Ltd.

14 Nov. 2012 Nova Scotia