Multi-beam echo sounders can be used for more than just bathymetry. They can be used for bottom classification, leak detection, harbor protection, and detecting sunken heavy oil. A test was conducted at the Ohmsett test facility to detect different types of sunken oil using multi-beam echo sounder data and acoustic backscatter properties. The results showed a 91% detection rate of oil areas with a 20% false alarm rate on non-oil areas.

1. Multi-beam Echo-sounders (MBES)
not only for bathymetry
The use of MBES for bottom classification, leak
detection, harbor protection and more.
by Simon M. Barchard
RESON
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2. Agenda
● Introduction
● MBES in survey configuration (bottom looking)
Bottom Classification
Sunken Heavy Oil Detection
● Forward looking MBES
Water side security (harbor protection)
Leakage Detection
● Q&A
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3. Introduction
● Advanced uses of MBES data require processing and integration with motion
and other sensors
● PDS2000 is the backbone of RESON’s advanced processing solutions
● Some facts about PDS2000:
PDS2000 Multibeam is a Hydrographic Survey software suite
Versions for Multibeam, Singlebeam and Dredging
Integrated multibeam data acquisition,
navigation and guidance.
Handles SeaBat 7k bathymetry, snippets and sidescan.
Interfaces to all commonly used navigation sensors
Scalable to installations with multiple sensors
3D Multibeam Data Editor with integrated CUBE processing
Data modeling & Volume computations
Data export to a variety of formats
● The SeaBat 7k platform is used for advanced applications
● Capabilities include:
Bathymetry
Backscatter (sidescan and/or snippets)
Forward looking sonar imagery
Watercolumn mapping
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4. Introduction continued…
PDS2000 also allows for interactive data processing of data with
snippets and CUBE
Snippet
data
CUBE
Model
An explanation of snippets will follow later in the presentation
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5. Bottom Classification
Backscatter corrections
GeoCoder is the tool used by PDS2000 to perform bottom
classification, licensed from UNH, developed by Luciano Fonseca)
● GeoCoder is a software application and include algorithms and
interface for visualization and analysis
● Bottom classification through the application of AVO (Amplitude
versus Offset) - Variation of acoustic backscatter with the angle
of incidence is a an intrinsic property of the seafloor.
● Backscatter is corrected for radiometric and
geometric distortions Acoustic model
Gain, power, pulse width, Beam pattern etc… Interface backscatter
Volume backscatter
● Objective is to determine parameters for the
backscatter inversion model
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6. Bottom Classification
GeoCoder examples
● Integrated approach
● Loading of backscatter, navigation and bathymetry data in GeoCoder directly from PDS2000 Log files
● PDS2000 executes the steps normally performed by GeoCoder user interface
● Write data to a PDS2000 Grid model
● Backscatter mosaic
● AVO parameters
● Seafloor properties
● Bottom types
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7. Detection of Sunken Heavy Oil
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8. Detection of Sunken Heavy Oil
Oil Spill Statistics & reason for USCG Study
● Analysts for the Oil Spill Intelligence Report, reported that spills
greater than 10,000 gallons (34 tons) have occurred in the waters of 112
nations since 1960. But they also reported (Etkin 1997) that oil spills
happen more frequently in certain parts of the world.
● No efficient solutions for detection of heavy fuel oil on
seabed exists
● Sunken Oil is a source of pollution that is of
significant detriment to the environment
● US Coast Guard’s Research and Development Center
(USCG RDC) identified remote detection and monitoring of
sunken oil as one of the key targets for further
government funded research
Requirements:
Wide area surveillance & identification
Localized positive identification of oil
● The USCG RDC awarded RESON, Inc. a contract to supply a Proof of Concept to
detect heavy oil on the sea floor along with partners:
Flemming Hvidbak of FlemmingCo environmental and oil spill professional with 24 years
of experience within the oil spill industry
University of New Hampshire: Center for Coastal & Ocean Mapping Joint Hydrographic
Center (UNH:CCOM JHC), Project scientist: Dr. Luciano Fonseca
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9. Detection of Sunken Heavy Oil
Sidescan & Snippets Imagery Outputs
● Sidescan and Snippets (aka
seafloor backscatter) both provide
imagery of the seafloor however,
due to the fact that Snippets
provides backscatter/ amplitude for
each footprint (versus average of
each side), the detail is much more
pronounced.
● The result are mosaics that are
easily overlain with digital terrain
models (bottom) that provide
invaluable information of seafloor
substrate and morphology.
Bottom Detect
300 300
Snippets
Sample
Window Size
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10. Detection of Sunken Heavy Oil
DTM with Snippets Overlay
Rock Reef Sand Waves with
Gravel Troughs
Snippets Acoustic Backscatter Provides a quantitative method to identify different
substrates based upon their acoustic “reflectivity”. The harder returns (i.e. Rock) in
this image are dark grey while the softer returns (i.e. sand/silt) are light grey.
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11. Detection of Sunken Heavy Oil
Acoustic Detection Principle
● The detection algorithm has used the fact that the
backscattered acoustic field depends on the angle between
the incoming field and the seabed
● This angular response is different for different types of
sediment
Amplitude Snippet data over one beam footprint.
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12. Detection of Sunken Heavy Oil
Test Facility
● Prototype test performed at Ohmsett test facility in New
Jersey.
● Ohmsett’s above ground concrete test tank is one of the
largest of its kind, measuring 203 meters long by 20
meters wide by 3.4 meters deep.
● The tank is filled with 2.6 million gallons of saltwater.
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13. Detection of Sunken Heavy Oil
Test setup
An area of size 40 ft x 40 ft was applied with
10 trays of size 8 ft x20 ft.
Oil types used in the test: Oil #6, Tesoro, Sundex and asphalt
2
4
6
8
10
12
2 4 6 8 10 12
Photo of trays on bottom of test tank
Sketch of the entire test area for the Prototype
Demonstration Test at OHMSETT 2009
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14. Detection of Sunken Heavy Oil
Results
Detected area is calculated
and compared to the Actual
(according to USCG sketch)
Detection rate Λ Oil / ΓOil 91%
False alarm rate Λ NoOil / ΛTot 20%
If the OHMSETT test detection-
processing time is transferred to a
1 square mile survey at 30m
depth the processing time will be
about 12 hours.
RESON’s Solution is accepted
and now endorsed by the US
Coast Guard
Operational scenarios include use with Bathymetric MBES system located on
surface vessel or ROV
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15. Waterside Security (WSS)
Operational requirements:
● Detect combat swimmers
● Localize and track
● Illuminate entire surveillance area with each
ping
● Track long enough to distinguish between
marine life and threat
Automatic Detection & Tracking (ADT)
● Applied on all FLS Harbor Protection
● Analyzes sonar echo sequence and
suppresses static background
● Automatically detects and tracks moving
targets
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16. WSS Video
SeaBat 7112
NATO HPT2008 Trials - Germany
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17. Leakage Detection
for subsea environments
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18. Introduction
● RESON has developed a technology concept for the detection of leaks
from the vicinity of subsea templates and structures
● Leaks include hydrocarbons (gas or liquid), hydraulic fluids and other
pollutants
● Based on SeaBat sonar technology and includes automated detection
algorithms intended to be used in fixed long term subsea installations
Basic principle:
Sonar ‘ping’ transmits energy into water
Leak media reflects energy based on
Acoustic Reflection properties
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19. Leakage Detection
Are there other options?
Leakage Detection technologies:
● Chemical sniffers
point sensors, can’t cover an area
positive ID of leak substance possible
● Video cameras: limited range in turbid water
● Passive acoustics (hydrophones only):
leak has to make a significant level of noise
Sensitive to environmental background noise
Advantages of SeaBat (sonar) technology:
● Detection of leaks not emitting noise by use of acoustic backscatter
● Wide area coverage
● Able to detect various leak media (gas, oil, MEG etc.)
● Sonars are also passive – sonars can also detect leak noise in similar manner
to hydrophones
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20. Post processing of data collected at SINTEF
RESON participated in an evaluation of Leak Detection technologies at
SINTEF, Scandinavia’s largest research institute.
● A number of leak scenarios were tested and various equipment from
chemical sniffers to video technology were put to the test
Below: 10bar crude oil leak through 0.7mm nozzle – not easy to see in
raw data, tank in a nasty acoustic environment
The improvement from processing of the raw data is obvious
The tank was small, so only short range tests were possible
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21. RESON follow up testing at long range
Korsør Naval Harbor
Air
Leak
6bar
(6m range)
Air
Leak
2bar
(28m
range)
Only air gas leaks were possible sue
to environmental concerns
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22. ‘Real life’ operations - offshore leak detection from ROV
Some interesting data was gathered (videos follow) and the system was able to find
the leak
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23. The site of the big leak
As the majority here are hydrographers I’ll conclude with an interesting bathymetric image
There are many new and exciting applications for multi beam echo sounder technology and
RESON is at the forefront for new application development
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