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Asset Management Made SimplerSubsea Asset Location Technologies
(SALT) Ltd.Lisa Symes
–
Principal Engineer
Agenda
• Introduction to the SonarBell®
• Unique features of the SonarBell®
• Case Studies:• Commercial Applications
• Case Study : Monitoring movement of a subsea
cable using a Geographical Information System
SonarBell®
–
ProvenanceSonarBell®
developed by UK MoD Defence Science
Technology Laboratories (DSTL) to provide:
• A highly efficient & non magnetic sonar target
• Easy to handle
• Minimal maintenance
• Can
be
tuned
to
resonate
at
a
specific
frequency
‐
or multiple frequencies
• Multiple Echo Response
• Better value than alternatives
• The SonarBell®
works through the
constructive interference of sound waves
when they meet after transiting the shell
and core
• It is totally passive and omni‐directional.
• Maximum target strength varies from ‐3dB
to ‐20dB across the range of 4kHz to
900kHz*
• The frequencies at which this phenomena
occurs depends on the shell thickness
• The range depends on SonarBell®
size, and
frequency of the sonar
Technology –
What is the SonarBell®?
* For a 200mm sphere
Sonar Reflector• Ability to see at range 0 – 2km
• Ability to detect over and above reverb
• Very distinctive echo structure not found naturally
• Environmentally inert / stable
• Limited acoustic energy in the water
• Quick / easy to measure
• Accurate
• Ability to locate in absolute coordinates
• Import locations in to a GIS
• Unique acoustic signature
• Manage
position
of
asset
throughout
life
cycle
(up
to
25
years)
Independently validated by
SonarBell®
frequency responseEach SonarBell®
unit can be customised to give the
following results:
• Calibrated to a target strength at a required frequency
• A broadband frequency response• A single / multiple frequency response peaks• Coated to only respond at certain frequencies
Top Image: Indicates the ability to have a general “broadband”
signal response.
Bottom Image: (red‐
front reflection / blue is rear echo) – designed
to provide peak response.
SonarBell®
Calibrations
Front Echo Back Echo
Target Stren
gth (dB)
Frequency (kHz)
Target Stren
gth (dB)
Rotation ( °)
Independent validation
Target strength validated by
PhD student: Alan Islas
CitalPhD supervisor: Philip Atkins
200mm
• How to Measure SonarBells
Acoustic Size
• SonarBell®
has a two echo response
• See graph (Time history)
• First echo (Point A)
o Front face of unit
o Low level
• Second Echo (point B)
o Inside shell face
o High level focused return
• Use second echo because :‐
• Higher levels
• detectable over longer distances
SonarBell®
MeasurementsPoint A Point B
200mm50mm
• Distinguishing
between
different
SonarBells
acoustically,
is
made
easier
by
changing
the
overall
diameter of the SonarBell®.
• The
acoustic
diameter
can
be
found
by
measuring
the
time
difference
between the front and back echo.
• The
acoustic
diameter
is
larger
than
the balls physical diameter due to the
speed
of
sound
in
the
core
being
slower
than
the
speed
of
sound
in
water
Distinguishing between different diameters
Sonar data
Process
feature’1’
Process feature’2’Process feature’3’
Process feature’n’
SonarBell®
locations
Process feature’4’
Detecting SonarBells
unique echo structure
• SonarBell®
software enables:
• Automated accurate
location positioning
• SonarBell®
characterised
by unique features
• SonarBell®
software “searches”
for these unique features to
label SonarBell®
locations
Raw sonar data Detection SoftwareRaw data turned off;
detections left on
Detection software in use
Application : Installation and Identify
Case Studies
Commercial Market ApplicationsThere are a huge number of commercial opportunities for
SonarBell®:
• Seismic cable monitoring
• Subsea pipes and cables
• Scientific instrument location
• Diver location
• ROV/AUV monitoring / docking
• Fishing net recovery
• Marking wrecks / obstructions / dredging
• Wreck artefacts
Commercial Market applications cont...Fishing:• 1.4 million commercial (<12m LOA) fishing vessels• Supports fishing operations, net / pot and trap recovery• Plans to make SonarBell®
a legal requirement for commercial
fishing
gear in EU
Sensor Calibration:• Accurate target strength up to ‐3dB target strength• Simple calibration of MBES systems without need for reference site • Supporting major manufactures e.g. Kongsberg, Reson, Atlas
Wreck Marking:• 116,880 wrecks listed worldwide• Accurate location of valuable artefacts (including GPS positioning)• Supporting
UK
listed
wrecks
management,
conservation
and
recreation
Marine Archaeology
Countess of Erne
SonarBell®
Scientific instrument location:• Marking and identifying scientific environmental
equipment during deployment e.g. BAS, GHD and
Oceaneering• Aids through project management and future recovery
of asset
Subsea pipes and cables:• Site
selection,
planning,
deployment,
maintenance,
retrieval and disposal of assets• Operational
support
for
seismic,
geo‐physical
and
hydro‐carbon related projects
Commercial Market applications cont...
Monitoring the Movement of Subsea CablesOverlay of geo‐referenced sonar data SonarBell®
individual coordinates
referenced
SonarBell®
used as a node along cable
SonarBell®
coordinates plotted Each unit labelled with an identifier and
lat / long
Subsequent survey
Thankyou
For Listening