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Fugro Survey Ltd,

Overview of acoustics pipeline inspection techniques. A discussion on the current techniques being employed for non visual

pipeline inspection.

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Introduction

• Overview– Side Scan Sonar– Pinger

• Platforms– Near shore– ROTV – Focus-2

• Enhancements and Data Quality• Processing and Interpretation

• High Resolution MBE– Additional Benefits– Products

• Future

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Geophysical Tools

• SSS– Primary Tool

• Detection of Exposures, Damage, Spans, Debris, Position– Mounted on

• Tow fish• ROV• ROTV

• Pinger (Sub Bottom Profiler)– Depth of Burial– Mounted on

• Hull of Vessel• Tow fish

– Lateral crossing of pipeline• Key components of risk based inspection regime • Often first phase of pipeline inspection, flowed by Visual Inspection programme

– ROV Based

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Near shore Pipeline Inspection

• Near shore - Shallow Water –– ROV not practical– ROTV not practical– Typically small vessel with free tow SSS fish – Tow fish positioning by logged cable layback from stern– Or small USBL system– Also high resolution MBE

• Can be limited in shallow water due to survey offset from pipe

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ROTV for API

• FOCUS 400 Remotely Operated Towed Vehicle (ROTV) introduced in 1995

• FOCUS 1000 and 1500 used by other contractors• ROTV used extensively for North Sea pipeline inspections. • Typically used as a SSS platform, • Typical Fugro annual inspection distance in excess of 6000 kilometres• New vehicles in 2006 FOCUS-2…. In use by a number of contractors

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FOCUS-2

• Based Upon FOCUS-400 experience– 100+% Redundancy

• 2 Vehicles – HOT SWAP• 2 Tow cables• Plus additional spares

– Minimal Downtime – Maximum Utilisation– Fast Results

• 400m Depth Range• Fibre Optic Tow Cable• State-of-the-Art Technology…

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FOCUS-2 Technological Advances

• Carbon-Fibre Body– Lighter, Stronger– More Manoeuvrable

• Enhanced Man Machine Interface– Auto Pilot tools

• Follow Pipeline• Maintain Altitude, Offset

• Fibre Optic Multiplexer– High Bandwidth

• Increased Payload Diversity…

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Acoustic Pipeline Inspection Payload

• Digital Side Scan Sonar– EdgeTech Full Spectrum 4200– 410kHz 50m Range– Improved Image Resolution

• Fibre-Optic Gyrocompass (Heading Sensor)– Oceantools MiniFOG– Pitch and Roll– Improved Positioning Accuracy

• Altimeter• Depth Sensor• USBL Responder• Optional

– Multibeam Echosounder– Doppler Velocity Log

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Data Example - Exposed Pipeline

ROTV Advantages:

Stable Vehicle

Quiet Platform

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Data Examples – Rock Dumps

ROTV Advantages:

Optimum Position

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Data Examples - Structures

SSIV

Valve Prot.

ROTV Advantages:

Optimum Altitude

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Data Examples – Pipe Displacement

ROTV Advantages:

Rapidly Manoeuvrable

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Data Examples – Weightcoat Damage

ROTV Advantages:Onboard Gyrocompass

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Data Examples - Debris

ROTV Advantages:Speed of Survey3 ½ - 4 Knts140-160km/day

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Improved Positioning

• MiniFOG provides true heading information on ROTV • Sonar interpretation is corrected in processing to produce

accurate pipe event positions

• Partnered with accurate USBL and HP Surface positioning– (HiPAP and StarfixXP/HP)

If the difference between Heading and CMG (tow direction) is 20°, at 20m range this would produce an error of over 7m

With a FOG fitted we see severe changes in heading - 40° in less than a minute

FOG Heading

CMGROTV

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Processing and Interpretation

• Core of specialist personnel– Senior Geophysicist – Interpretation Team Leader

(3-4 years experience, 70 - 100 days/year inspection)– Three Geophysicists– Senior Surveyor/Data Processor – Processing Team Leader– Two Data Processors

• Annual training course involving all key personnel• Company training manuals for interpreters/data processors• Annual 6 month programme in North Sea• On-going development programme

– Efficiency– Enhancements

• Exports to Asset Management systems

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Optimised Interpretation Software

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Data Management

Database for Status Tracking

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Result Presentation - GIS

• Data lends itself to display in GIS• Primary 2D data

•ArcGIS the most popular format for the oil and gas Industry

•Products supplied in geo-referenced databases with attributes for further query

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Result Presentation - Charts

• Automated Chart Production Tools• Year on Year comparison

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Multibeam Echosounder

• High Resolution Vessel Mounted MBE – Reson 8125, EM710

• Shallow Water solution to provide additional information about the situation of the pipeline and the surrounding seabed. Increased depth range with systems like EM710.

• Additional Tool for determination of Pipe position– Increased position certainty - surface sensor

• High resolution bathymetric model of seabed including pipeline.– Cross Profiles

• Or ROTV Mounted MBE ( EM3002)• ROTV geometry not ideal for acquisition of MBE during SSS

phase

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20m

50m

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MBE – Pipeline in its surroundings.

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MBE – Pipeline in its surroundings.

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MBE – Pipeline in its surroundings.

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MBE – Pipeline in its surroundings.

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Result Presentation - MBE

• Incorporating– ROTV– MBE– Pinger

• Presenting– Contours– Shaded Relief– Cross Profiles– Plan Events– Seabed Profile– Depth of Burial– Pipe Status

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Eyeball ROV on Acoustic Inspection Vessel

• Spot Dives on critical events from ROTV survey as identified• Small Sections of GVI / CVI • Digital Stills Photography• CP (Contact, Proximity & Field Gradient)• One vessel, one mobilisation, fast results…

Inspection

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Future Developments

• Synthetic Aperture Sonar (SAS)– Increased resolution

• Automated processing tools– Pipe detection

• MBE Backscatter– Hull mounted and ROV based.– Typically around a 20 fold increase in data volume– Tool for detection of pipe position, automated

• AUV ?• ROTV positioning

– DVL– INS

• Presentation tools– Raw data viewer with results for Operator

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Summary

ACOUSTIC INSPECTION SURVEYS• Accurate delineation of pipeline position• Accurate Event Listings• Higher resolution survey data• Fast Results• Reduced Vessel Mobilisations• Reduced ROV Inspection Scope

• Limitations– Burial

• limited to pinger crossings• Additional phase of survey

– One pass operations are offset from pipeline