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Shelburne Basin Venture Exploration Drilling Project
Marine Acoustic Monitoring Plan
Project Shelburne Basin Venture Exploration Drilling Project
Document Title Marine Acoustic Monitoring Plan
Document Number EP201601210732
Document Revision 04R
Document Status Issued for Authority Approval (IFAA)
Owner / Author L. Smandych/D. Smart (JASCO Applied Sciences)
Issue Date March 15, 2016
Expiry Date None
Security Classification Unrestricted
Disclosure External via CNSOPB and CEAA
TABLE OF CONTENTS
1. INTRODUCTION ............................................................................................................... 1
2. PROGRAM PURPOSE AND OBJECTIVE ......................................................................... 1
2.1. Predicted Sound Levels ............................................................................................ 2
2.2. Design ...................................................................................................................... 2
2.3. Equipment ................................................................................................................ 4
2.4. Recording Configuration and Field Operations .......................................................... 7
2.5. Analysis and Reporting ............................................................................................. 8
LIST OF FIGURES
Figure 1: Overview of the Program design ................................................................................. 3
Figure 2: Deep water static recorder configuration ..................................................................... 5
Figure 3: Catenary based drifting acoustic recorder ................................................................... 6
Figure 4: Example power spectral density levels and 1/3-octave-band pressure levels plotted
over frequency ........................................................................................................... 9
Figure 5: Sample of a sound source verification regression plot, showing peak SPL, 90% rms
SPL, and SEL versus range* ...................................................................................... 9
LIST OF APPENDICES
Appendix A Shelburne Basin Venture Exploration Drilling Project - Acoustic Monitoring Plan
(October 21, 2015 submission)
Shelburne Marine Acoustic Monitoring Plan
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1. INTRODUCTION
In accordance with Condition 3.12.3 of the Decision Statement issued under Section 54 of the
Canadian Environmental Assessment Act, 2012 (CEAA, 2012), to Shell Canada Limited (Shell)
for the Shelburne Basin Venture Exploration Drilling Project (the Project):
The Proponent shall monitor effects on fish and fish habitat, including marine mammals
and sea turtles, to verify the accuracy of the predictions made during the environmental
assessment and to evaluate the effectiveness of mitigation measures identified under
conditions 3.1 to 3.11, including:
3.12.3 Verifying predicted underwater noise levels with field measurements during
the first phase of the drilling program. The proponent shall provide to the Board a
plan on how this will be conducted at least 30 days in advance of drilling and the
monitoring results within 90 days after a well is suspended and/or abandoned.
Shell submitted the Shelburne Venture Exploration Drilling Project: Marine Acoustic Monitoring
Plan (the Plan) to the Canada-Nova Scotia Offshore Petroleum Board (CNSOPB) on October
21, 2015 outlining a program the collect acoustic data to verify the underwater noise levels
(Appendix 1). The Plan was to be implemented by JASCO Applied Sciences (JASCO) during
the first phase of Project drilling activities. An attempt was made to complete the Program
during the drilling of the first well (Cheshire, L-97), however offshore weather conditions and
other operational constraints precluded contractor safety and the safe deployment and retrieval
of the catenary recorder.
Given the constraints imposed by weather conditions on Plan implementation, Shell has been
working with JASCO to modify the Plan in an effort to lower health, safety and environment
(HSE) risk, circumvent potential weather restrictions, and improve the acquisition of quality data
to meet the intent of Condition 3.12.3. The proposed amendment to the Program involves the
addition of a second static recorder. The addition of a second moored recorder may provide
improved data that can be safely acquired in a wider range of weather conditions and during
shorter windows of drilling activity. This option offers a higher probability of gathering good
quality acoustic data with less overall risk. The catenary recorder will be used should there be
an opportunity to align drilling activity with a favorable weather window (break in weather and/or
less than Beaufort Scale, Sea State 2).
2. PROGRAM PURPOSE AND OBJECTIVE
Shell will implement the Plan during the first phase of the drilling program (i.e., the two well
drilling program which commenced in Q4 2015). The primary objective of this Plan is to describe
how underwater sound levels from a mobile offshore drilling unit (MODU) predicted in the 2014
Shelburne Marine Acoustic Monitoring Plan
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Project Environmental Impact Statement (EIS), will be verified with field measurements. The
predicted sound levels in the EIS were based on existing Environmental Assessment (EA)
reports, Strategic EAs, monitoring programs and scientific literature. For this proposed
program, field measurements will be verified based upon the sound generated by the Project
MODU, the Stena IceMax.
2.1. Predicted Sound Levels
The MODU will generate and release three main sources of underwater sound:
vessel operation sounds (mechanical and vibration);
thruster cavitation from the dynamic positioning (DP) systems; and
direct drilling sound from the drill string and drill bit.
During drilling, it is expected that all sources of sound will be emitted continuously (non-
impulsive). Sound Pressure Levels (SPLs) emitted from the operating MODU are likely to range
between 130 and 190 dB re 1uPa @ 1 m. All criteria (noise thresholds that may elicit impact on
fish, turtles, and marine mammals), are found in Section 7 of the EIS (http://www.ceaa-
acee.gc.ca/050/document-eng.cfm?document=101799).
Sound level (SL) measurements will provide reference source levels of the drilling vessel and
equipment used during drilling. Whereas the source levels applied in the EIS relied primarily on
estimated source levels derived from existing literature, the actual sound levels that will be
introduced into the underwater environment during drilling will be recorded and measured and
will be compared to those applied in the EIS.
The purpose of taking field (underwater) sound level recordings will be:
1. to measure the drilling sound levels at orientations to the MODU and characterize the
sound levels associated with drilling activities;
2. to analyze acquired data and verify the drilling sound data used in the EIS; and
3. to deliver the results in a final report.
2.2. Design
This Acoustic Monitoring Program will use two static recorders and a single drifting catenary
recorder, if weather and sea state conditions permit (Figure 1). The static recorders will be
deployed upon arrival in the Project area and will record continuously for approximately three (3)
days (Program duration). One recorder will be positioned along the beam of the MODU, and the
other along the stem-stern line of the MODU. It is anticipated that the sounds from the dynamic
positioning system thrusters will have a directional component that can be measured by having
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the recorders oriented at 0 and 90 degrees relative to the vessel. Both static recorders will be
deployed approximately 2000 m from the MODU.The continuous recordings will provide an
assessment of the variability in the sound levels from the MODU over its daily operating cycle
and in different sea states. The static recorders will also document the sound levels near the
seabed, which would be the levels encountered by deep diving odontocetes that are known to
be in the area. The static recorder sound levels will be back-propagated to determine the source
level of the MODU as a function of frequency. Conductivity-temperature-depth (CTD) data will
be collected as an input to the propagation loss modeling for the back propagation.
Figure 1: Overview of the Program design
Attempts will be made to have the drifting recorder collect data at multiple ranges from the
MODU at a depth of 100 m. Because the recorder drifts, the measurements will be relatively
short, on the order of 15 minutes each. The drifts will be arranged so that the recorder’s closest
points of approach (CPA) to the MODU will range between 600 m and 4000 m (4 km) The
sound levels from these drifts will be analyzed to determine the source level of the MODU.
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2.3. Equipment
The static recorders will be deployed approximately 2000 m from the MODU. The hydrophone
will be located approximately 25 m above the seabed (Figure 2). Each recorder will be left to
record continuously until completion of the Program (approximately three days). The static
recorders will be weighted to the seafloor by six (6) stacked 20 kg Olympic plates (40 cm
diameter). Upon completion of the monitoring, the release mechanism on the mooring will be
triggered from the surface allowing the recorder to disconnect from the anchor weight and rise
to the surface for retrieval. The anchor weights will remain on the sea floor.
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Figure 2: Deep water static recorder configuration
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The catenary mooring will be a drifting recording instrument that will be deployed over the side a
vessel used to support the Program. The mooring consists of a surface float and an ‘S’ shaped
catenary mooring that isolates the hydrophone from surface motion (Figure 3). The surface float
includes a visual flasher, radar reflector, and Iridium GPS beacon to track its location. Iridium
messages will be available to Shell representatives ashore, as well as on the MODU so that no
interference occurs with operations. The GPS logs will be used to infer the range of the
hydrophones from the project activities during the range-versus-received level analysis.
The catenary mooring acts as a spring to isolate vertical motion of the surface float from the
hydrophones. When properly designed and tuned for the sea state and the mass of the
recorders all of the surface motion is absorbed by the sinking section of the ‘S’ leaving the
floating section and hydrophone undisturbed. The mooring team will simulate and physically
tune the mooring to ensure the hydrophones remain isolated from the surface in all sea states
over which operations are expected to occur.
Figure 3: Catenary based drifting acoustic recorder
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The AMAR at the base of the drifting system is fitted with a Star Oddi depth sensor that is used to confirm the correct functioning of the catenary line and settled depth of the hydrophones.
2.4. Recording Configuration and Field Operations
Both static and catenary recorders will sample at a rate of 128 000 samples per second (128
ksps) using a JASCO AMAR recorder and a GeoSpectrum M14 hydrophone. The M14 is a
specially designed hydrophone that provides calibrated sound levels from below 2 Hz to above
20 kHz. The combined response of the M14 and AMAR will return all of the data necessary to
perform a complete analysis of all radiated sound from the drilling activity.
The ability to perform the measurements will depend on weather conditions and sea state. Good
weather conditions are required to safely handle, deploy and retrieve the two static systems and
catenary recorder, however unlike the catenary system, which requires a sea state of
approximately 2 m, the static recorders are easier to deploy and may be deployed in higher sea
states (up to Sea State 5). The deployment of the static recorders may be completed in a
higher seas state because the overall mooring is less complex (reduce fouling risk) as
compared to the catenary mooring, therefore requiring less time to deploy. Each static recorder
will require a shorter favorable weather window of approximately two hours to deploy and two
hours for retrieval. Other advantages of the static recorders include:
once the mooring is in place on the sea floor, the recorders are not impacted by surface
conditions and can be left to record continuously through all sea states. The quality of
measurements may therefore be improved;
the moorings can be left on the sea floor and retrieved at the end of three days
(recorders have a recording capacity of five days). This may provide more opportunity to
capture favourable weather windows;
the depth of recorder is approximately 25 m off the seabed, therefore more favourable
for capturing drilling noise measurements;
data will be recorded continuously therefore there is more opportunity to align with the
Project drilling schedule to capture drilling noise. Unlike the catenary system, periods of
continuous drilling are not required because the static moorings will record all activity
over the three days operation period. Sounds can then be sourced/confirmed post field
via the MODU operations logs and be back-propagated to determine the source level of
the MODU as a function of frequency; and
depth of recorder is advantageous for documenting the sound levels near the seabed,
which would be encountered by deep diving odontocetes in the area.
If the MODU is fully operational with a sea state of approximately 2, it may be possible to perform the required drift measurements within approximately 30 to 45 minutes at each ranges (between 600 m and 4 km CPA). For each MODU machinery state to be measured JASCO will:
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Test and calibrate the recorders, hydrophones, and Iridium beacon;
Deploy the mooring approximately 4 km downwind from the MODU, then move the deployment vessel at least 1 km from the recorder and minimize the sounds (engine noise) produced by the vessel;
After approximately 15 minutes, return to the mooring and use a boat hook to grab the 20 m tether line. Secure this line to the vessel side. Verify from the deployment and retrieval GPS locations that the mooring is drifting downwind and is not being taken towards the MODU by a water current. During the transit, download the data from the AMAR and verify that the MODU sounds are being recorded above the sounds from the deployment vessel and any surface motion induced noise; and
Slowly tow the mooring to another location(s) downwind of the MODU and repeat the measurements.
2.5. Analysis and Reporting
On completion of the field measurement phase, the data will be downloaded from the AMAR
recorders and the full data set will be processed to determine the per-second peak, rms SPL,
SEL and 1/3-octave-band rms SPLs. The MODU operations logs will be reviewed to select
periods with different machinery states for analysis. The data from the static recorders will be
back-propagated to determine the source spectrum (Figure 4) of the MODU in each machinery
state, as well as the source level variability. Since the recorders will be located within
approximately 2000 m of water, simple spherical spreading is expected to be accurate for the
back propagation, however, acoustic propagation models using the locally measured sound
speed profile will also be used in case there is significant refraction in the environment.
Summary of the data from the static recorders will also be provided that include percentile
exceedance levels, decade band levels and histograms, and long term spectral averages of the
received sound levels.
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Figure 4: Example power spectral density levels and 1/3-octave-band pressure levels
plotted over frequency
For the catenary recorder, for the time periods where the deployment vessel was idling far from the recorder the peak rms SPL and SEL levels will be plotted versus range to the MODU, and then a regression applied to the data to determine the source levels and spreading loss (Figure 5).
Figure 5: Sample of a sound source verification regression plot, showing peak SPL,
90% rms SPL, and SEL versus range*
*Solid line is best fit of the empirical function to Lp90 values. Dashed line is the best-fit shifted to exceed
90% of the Lp90 values (90th percentile fit). The equations show the effective source level (in this case
213.4 dB) and the spreading loss (16.4 log (R)) in the environment.
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Verification and comparison of the analyzed drilling sound levels will be made with those
predicted in the EIS for the Project. Shell will submit a Final Acoustic Monitoring Report to the
CNSOPB within 90 days after the well is suspended and/or abandoned.
Appendix A: Shelburne Basin Venture Exploration Drilling Project - Acoustic Monitoring Plan (October
21, 2015 submission)
Shell Canada Energy 400 - 4th Avenue S.W.
P.O. Box 100, Station M
Calgary, Alberta T2P 2H5
Internet www.shell.ca
October 21, 2015
Eric Theriault
Advisor, Environmental Affairs
Canada-Nova Scotia Offshore Petroleum Board
1791 Barrington Street, 6th Floor, TD Centre
Halifax, NS, B3J 3K9
RE: Shell Shelburne Venture Exploration Drilling Project
CEAA Condition 3.12.3; Marine Acoustic Monitoring Plan
On June 15, 2015, Shell Canada Limited (Shell) received the Decision Statement Issued under
Section 54 of the Canadian Environmental Assessment Act, 2012 for the Shelburne Basin
Venture Exploration Drilling Project (the Project). CEAA Condition 3.12.3 states:
The Proponent shall monitor effects on fish and fish habitat, including marine mammals and
sea turtles, to verify the accuracy of the predictions made during the environmental
assessment and to evaluate the effectiveness of mitigation measures identified under
conditions 3.1 to 3.11, including:
3.12.3 verifying predicted underwater noise levels with field measurements during the first
phase of the drilling program. The proponent shall provide to the Board a plan on how this
will be conducted at least 30 days in advance of drilling and the monitoring results within 90
days after a well is suspended and/or abandoned.
In compliance with CEAA Condition 3.12.3, Shell submitted a draft Shelburne Venture
Exploration Drilling Project: Marine Acoustic Monitoring Plan (the Plan) to the Canada-Nova
Scotia Offshore Petroleum Board (CNSOPB) on September 17, 2015. Shell has since
contracted JASCO Applied Sciences (JASCO) to complete the acoustic monitoring
program for the Project. Based upon their experience and expertise, the Plan has been
updated (please see attached). The implementation of the Plan will occur during the drilling
of the first Project well (Cheshire).
As part of the acoustic monitoring, Shell proposes to use one (1) static recorder that will be
deployed 2000m from the MODU and left in place for approximately 3 days. The recorder
will be weighted to the seafloor by six (6) stacked 20kg Olympic plates (40cm diameter).
Upon completion of the monitoring, the release mechanism on the mooring will be triggered
Shelburne Acoustic Monitoring Plan October 21, 2015
2
from the surface allowing the recorder to disconnect from the anchor weight and rise to the
surface for retrieval. The anchor weight will remain on the sea floor.
Residual environmental effects of the deployment of the recorder are predicted to be not
significant. There are no Special Areas located within 2km of the proposed well location. The
deployment of the recorder to the sea floor could result in mortality of sessile benthic fauna
and infauna directly under the anchor weight, however given the size of the weight (40cm
diameter) disturbance, if any, will be minimal. Entanglement in the rigging between the
weights and the top of the mooring is likely not to occur given the short duration the mooring
will be in place. Although the stainless steel weights will remain on the sea floor, it is
anticipated that they will likely be colonized by epifauna over time and will not result in
significant adverse environmental effects on the benthos.
Sincerely,
Lara Smandych
Senior Environmental Planner
Shell Canada Limited
Shelburne Acoustic Monitoring Plan October 21, 2015
3
Shelburne Venture Exploration Drilling Project: Marine Acoustic Monitoring Plan
I. Introduction
In accordance with Condition 3.12.3 of the Decision Statement issued under Section 54 of
the Canadian Environmental Assessment Act, 2012, to Shell Canada Limited (Shell) for the
Shelburne Basin Venture Exploration Drilling Project (the Project):
The Proponent shall monitor effects on fish and fish habitat, including marine mammals and
sea turtles, to verify the accuracy of the predictions made during the environmental
assessment and to evaluate the effectiveness of mitigation measures identified under
conditions 3.1 to 3.11, including:
3.12.3 verifying predicted underwater noise levels with field measurements during the
first phase of the drilling program. The proponent shall provide to the Board a plan on
how this will be conducted at least 30 days in advance of drilling and the monitoring
results within 90 days after a well is suspended and/or abandoned.
Shell prepared a draft Shelburne Venture Exploration Drilling Project Marine Acoustic
Monitoring Plan to be implemented during the first phase of Project drilling activities. This Plan
was submitted to the Canada-Nova Scotia Offshore Petroleum Board (CNSOPB) on
September 17, 2015, approximately 30 days in advance of the commencement of drilling in
compliance with the CEAA condition. Below is the amended plan that will be executed by
JASCO Applied Sciences (JASCO), based out of Dartmouth, Nova Scotia.
II. Program Purpose and Objective
Shell will implement an acoustic monitoring program during the first phase of the drilling
program (i.e. the two well drilling program commencing Q4 2015). First Phase is understood
as the time period post spud and approximately mid-way through the 130 day drilling
schedule of the first well. At this time, field work would likely commence late Q4 2015 or early
Q1 2016.
The primary objective of this Plan is to describe how underwater sound levels from a mobile
offshore drilling unit (MODU) predicted in the 2014 Project Environmental Impact Statement
(EIS) will be verified with field measurements. The predicted sound levels in the EIS were
based on past Environmental Assessment (EA) reports, Strategic EAs, monitoring programs
and scientific literature. For this proposed program, field measurements will be verified based
upon the sound generated by the Project MODU, the Stena IceMax.
Shelburne Acoustic Monitoring Plan October 21, 2015
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Predicted Sound Levels:
The MODU will generate and release three main sources of underwater sound:
Vessel operation sounds (mechanic and vibration);
Thruster cavitation from the dynamic positioning (DP) systems; and
Direct drilling sound from the drill string and drill bit.
During drilling, it is expected that all sources of sound will be emitted continuously (non-
impulse). Sound Pressure Levels (SPLs) emitted from the operating MODU are likely to range
between 130-190 dB re 1uPa @ 1m. All criteria (noise thresholds that may elicit impact on
fish, turtles, and marine mammals), are found in Section 7 of the EIS (http://www.ceaa-
acee.gc.ca/050/document-eng.cfm?document=101799).
Sound level (SL) measurements will provide reference source levels of the drilling vessel and
equipment used during drilling. Whereas the source levels applied in the EIS relied primarily
on estimated source levels derived from existing literature, the actual sound levels that will
be introduced into the underwater environment during drilling will be recorded and
measured and will be compared to those applied in the EIS.
The purpose of taking field (underwater) sound level recordings will be:
1. To measure the drilling sound levels at different distances and depths from the MODU
and characterize the sound levels associated with drilling activities.
2. To analyze acquired data and verify the drilling sound data used in the EIS.
3. To deliver the results in a final report.
Design:
The acoustic monitoring will use two components: a single drifting catenary recorder and a
single static recorder (Figure 1). The drifting recorder will collect data at multiple ranges from
the MODU at a depth of 100 m. Because the recorder drifts, the measurements will be
relatively short, on the order of 15 minutes each. The drifts will be arranged so that the
recorder’s closest points of approach (CPA) to the MODU are approximately 600, 1000, 2000,
5000, and 10000 m.
Time and weather permitting the drifts at each range will be repeated multiple times to
measure different operating states of the MODU and / or provide a larger statistical sample
in the normal operating condition. The sound levels from these drifts will be analyzed to
determine the source level of the MODU.
The static recorder will document the sound levels near the seabed, which can be
encountered by deep diving odontocetes. This recorder will record continuously for
approximately three (3) days which will provide an assessment of the variability in the sound
levels from the MODU over its daily operating cycle and different sea states.
Shelburne Acoustic Monitoring Plan October 21, 2015
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Figure 1: Overview of the program design
Equipment:
The catenary mooring will be a drifting recording instrument that will be deployed over the
side the chartered vessel used to support the acoustic measurement program. The mooring
consists of a surface float and an ‘S’ shaped catenary mooring that isolates the hydrophone
from surface motion (Figure 2). The surface float includes a visual flasher, radar reflector, and
Iridium GPS beacon to track its location. Iridium messages will be available to Shell
representatives ashore, as well as on the MODU so that no interference occurs with
operations. The GPS logs will be used to infer the range of the hydrophones from the project
activities during the range-vs-received level analysis.
The catenary mooring acts as a spring to isolate vertical motion of the surface float from the
hydrophones. When properly designed and tuned for the sea state and the mass of the
recorders all of the surface motion is absorbed by the sinking section of the ‘S’ leaving the
floating section and hydrophone undisturbed. The mooring team will simulate and physically
tune the mooring to ensure the hydrophones remain isolated from the surface in all sea
states over which operations are expected to occur.
Shelburne Acoustic Monitoring Plan October 21, 2015
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Figure 2: Catenary based drifting acoustic recorder
The AMAR at the base of the drifting system is fitted with a Star Oddi depth sensor that is
used to confirm the correct functioning of the catenary line and settled depth of the
hydrophones.
The static recorder will be deployed on arrival in the project area approximately 2000m from
the MODU. The hydrophone will be located approximately 25 m above the seabed (Figure
3). It will be left to record continuously until completion of the catenary recorder program
(approximately 3 days).
The static recorder will be weighted to the seafloor by six (6) stacked 20kg Olympic plates
(40cm diameter). Upon completion of the monitoring, the release mechanism on the
mooring will be triggered from the surface allowing the recorder to disconnect from the
anchor weight and rise to the surface for retrieval. The anchor weight will remain on the sea
floor.
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Figure 3: Deep water static recorder configuration
Shelburne Acoustic Monitoring Plan October 21, 2015
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Recording Configuration and Field Operations:
Both recorders will sample at a rate of 64 000 samples per second (64 ksps) using a JASCO
AMAR recorder and a GeoSpectrum M14 hydrophone. The M14 is a specially designed
hydrophone that provides calibrated sound levels from below 2 Hz to above 20 kHz. The
combined response of the M14 and AMAR will return all of the data necessary to perform a
complete analysis of all radiated sound from the drilling activity.
The time required to perform the measurements will depend on weather conditions and
operations at the MODU. If the MODU is fully operational and weather conditions are good,
it may be possible to perform all of the required drift measurements within a single day. For
each sound source to be measured, it will take approximately 30 to 45 minutes to collect
data at each of the five ranges (600, 1000, 2000, 5000 and 10000 m CPAs). For each MODU
machinery state to be measured JASCO will:
- Test and calibrate the recorders, hydrophones, and Iridium beacon;
- Deploy the mooring approximately 10 km downwind from the MODU, then move the
deployment vessel at least 1 km from the recorders and minimize the sounds (engine
noise) produced by the vessel;
- After approximately15 minutes, return to the mooring and use a boat hook to grab the
20 m tether line. Secure this line to the vessel side. Verify from the deployment and
retrieval GPS locations that the mooring is drifting downwind and is not being taken
towards the MODU by water currents. During the transit, download the data from the
AMAR and verify that the MODU sounds are being recorded above the sounds from
the deployment vessel and any surface motion induced noise;
- Slowly tow the mooring to a location 5 km downwind of the MODU. Move off at least 1
km and idle the vessel for 15 minutes;
- Return to the mooring, and tow it to a location 2 km downwind of the MODU and
repeat the measurements;
- Return to the mooring, and tow it to a location 1 km downwind of the MODU and
repeat the measurements;
- Return to the mooring, and tow it to a location 600 m downwind of the MODU, repeat
the measurements; and
- Time and weather conditions permitting repeat these measurements across wind or
downwind from the MODU.
Note that measurements will be made from the 10 km downwind range progressively closer
to the MODU, and the drift dynamics will be analyzed between drifts. The acoustics team will
ensure that there is no chance that the catenary mooring or acoustic support vessel will
enter inside the 500 m exclusion zone.
Each set of drift measurements will take 4 to 6 hours to complete. Shell anticipates that it will
not be possible to measure the operational sounds from the rig without the DP system on,
however it may be possible to measure with and without the drill operating. Three days of
measurements are allocated, which may provide at least two sets of drift measurements,
with and without the drill operating.
Shelburne Acoustic Monitoring Plan October 21, 2015
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Conductivity-temperature-depth (CTD) casts will be performed each day. The CTD data
may be necessary to help interpret any anomalous propagation results from the
measurements.
Analysis and Reporting:
On completion of the field measurement phase, the data will be downloaded from the
AMAR recorders and processed to determine the per-second peak, rms SPL, SEL and 1/3-
octave-band rms SPLs. For the time periods where the deployment vessel was idling far from
the recorder the peak rms SPL and SEL levels will be plotted versus range to the MODU, and
then a regression applied to the data to determine the source levels and spreading loss
(Figure 4). The 1/3-octave-band data will also be plotted as a function of range to
determine the source spectrum of the drill and MODU operations (Figure 5). A summary of
the data from the static recorder will be provided that include percentile exceedance
levels, decade band levels and histograms, and long term spectral average results.
Figure 4: Sample of a sound source verification regression plot, showing peak SPL, 90% rms SPL, and SEL versus range. Solid line is best fit of the empirical function to Lp90 values. Dashed line is the best-fit shifted to exceed 90% of the Lp90 values (90th percentile fit). The equations show the effective source level (in this case 213.4 dB) and the
spreading loss (16.4 log (R)) in the environment
Shelburne Acoustic Monitoring Plan October 21, 2015
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Figure 5: Example power spectral density levels and 1/3-octave-band pressure levels plotted over frequency
Verification and comparison of the analyzed drilling sound levels will be made with those
predicted in the EIS for the Project. Shell will submit a final acoustic monitoring report to the
CNSOPB within 90 days after the well is suspended and/or abandoned.