It was agreed on site that the deployment of the streamer for 2D UHR seismic acquisition was not necessary to the tests. Therefore, there was no 2D UHR seismic data to QC.
The sparker source was shot every meter, this corresponded to approximately 2 shots for every 1 second. An example of the amplitude and spectrogram of the signal recorded during passing over AMAR A is presented in Figure 6.6.
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Figure 6.5: Amplitude (top) and Spectrogram (bottom) of Sparker: example showing a section of data as the source transited over AMAR A sensor
6.5 USBL
The USBL system was used to provide positioning for the towed equipment and was switched on during the SSS tests unless stated otherwise in the Table 3.7.
The amplitude and spectrogram of the signal recorded on AMAR A are presented in Figure 6.6. A clear series of impulses was detectable against the ambient sound levels. The peak frequency of the signals is visible at around 25kHz.
Figure 6.6: Amplitude and Spectrogram of the USBL source example showing a section of data as the source transited over AMAR A sensor
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7. Quality Assurance and Control
7.1 Quality Assurance
All sensor data was acquired according to operational procedures and work practices written and in use on the Fugro Pioneer.
All operational procedures and work practices were in place and are currently available on the vessels. They are used to ensure that data is acquired as per Fugro requirements and is acquired consistently across shifts and across vessels.
7.2 Quality Control
Online surveyors and engineers onboard the vessels monitored the acquisition of data on a 24h basis. The online personnel completed the Online Log and Engineers’ Log to detail equipment in use, vessel characteristics (heading, speed etc), equipment settings and importantly any problems seen with the data acquisition during the survey.
The online log is presented in Appendix F.
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8. Quality, Health, Safety and Environment
The survey was planned and carried out in conformance with Fugro’s quality management system, which complies with the requirements of ISO 9001:2015, ISO 14001:2015 and OHSAS 18001:2007. More detailed descriptions of specific survey techniques and procedures are contained within Fugro standard procedures (a component of Fugro’s QHSE Manual - details of which can be inspected at the Fugro offices on request).
Prior to the commencement of survey operations, a project execution plan (PEP) consisting of Project Overview, Operations Plan, Quality Plan, Health, Safety, Security and Environment Plan (HSSE) and Emergency Response Plan (ERP) were submitted to Energinet Eltransmission A/S as per Table 8.1. These documents formed the basis for all planning in relation to this project.
Table 8.1: Project Execution Plan Documents
Fugro Document Revision Revision Date F176286-PEP-001_Overview (03) 3 17 May 2021 F176286-PEP-002_Quality Plan (02) 2 17 May 2021 F176286-PEP-003_HSSE Plan (03) 3 24 August 2021 F176286-PEP-004_ERP Plan (03) 3 17 May 2021 F176286-PEP-007_Ops Plan (04) 4 16 September 2021
A digital online survey log was completed during online operations and provided a detailed record of all activities and events that occurred onboard the survey vessel. Detailed
information relating to each surveyed line was recorded. This included date, time, line name, instrument setup parameters and highlighted any events or data quality issues.
The performance of the survey instrumentation was constantly monitored by the online surveyor and online geophysicist. Data quality was also monitored by the offline processors soon after data acquisition to ensure the data was typical of survey quality.
Data storage, control and archiving of the data were undertaken in compliance with the PEP and Fugro’s data management policy.
8.1 Quality Control
Information has been provided below on the quality control checks carried out during the operational phase of this project (Table 8.2).
Table 8.2: Summary of Quality Control Checks Carried Out Stage of Survey Check
Mobilisation
GNSS Health Check of primary navigation system using third party processing;
Node offset check and position comparison of primary and secondary navigation systems to a Leica 1200 PPK system;
Vessel draught check for MBES and navigation software;
Datum transformation verification from WGS84 to ETRS89 and vertical datum LAT;
Validation of heading sensor using RTK derived baseline;
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Stage of Survey Check
Conduct USBL verification/walk away check;
Beacon battery interrogation to prove battery life;
Undertake patch test to calibrate the alignment of the multibeam transducer and conduct latency check;
MBES repeatability test, noise test and system verification;
SVP and SVS comparison;
SSS heading calibrations, rub test, wet test and I/O test;
Verification of SSS and SBP positioning;
Check all instruments logging correctly.
On survey
Check MBES for data quality (power/gain/range, motion/weather artefacts, SVP vs SVS accuracy, feature resolution coverage, sounding density, noise interference, THU, TVU);
Check MBES files are being recorded (SIS) populating the correct folders;
Check GNSS navigation quality;
Check SSS data quality (snatch/weather artefacts, resolution, survey speed, layback);
Check SSS files are being recorded (both low and high frequency, XTF and JSF);
Check SSS data consistency, USBL navigation quality, correct range being recorded, towfish altitude;
Check SBP data recording at correct frequency and pulse rate for suitable data quality
Check SBP headers are correctly populated
Check SBP positioning relative to items observed in a secondary sensor
2DUHRS bird depth constantly monitored online.
In Dock
Vessel draught check for MBES and navigation software;
Cross check all sensor data quality and coverage to ensure specification has been met;
Back up data onto vessel server and hard drive;
Send back data to Fugro Netherlands office.
8.2 Vessel Navigation
Position quality for the primary and secondary GNSS receivers was continually monitored throughout the project and all positioning criteria were met. A navigation comparison check was performed prior to the start of the survey and confirmed that both the primary and secondary StarPack antennas on both vessels were providing consistent position information.
Vessel navigation was consistently maintained at an accuracy better than 0.1 m horizontally and vertically, through the StarPack primary and secondary systems.
8.3 Multibeam Echosounder
The multibeam bathymetry data collected were of good quality. Any noise present in the data was removed and the remaining data were corrected for variations in tidal height.
The multibeam backscatter data collected were of good quality. Optimum power and gain settings were utilised during data acquisition to ensure high quality acquisition. During the survey, multibeam range changes were minimised to maintain the quality of the MBES data.
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8.4 Subsea Positioning
The subsea positioning from data acquired with the USBL on, was generally good throughout the survey. During the scouting lines, the AMAR stations were detected in the MBES and SSS data and these positions compared. The SSS data for the scouting lines was found to have an average target position deviating less than < 2.0 m from the position of the same target derived from MBES. Magnetometer data was found to have an average target position deviating less than < 2.0 m from the position of the same target derived from MBES.
Reference is made to the Mobilisation and Calibration Report (Fugro Document No.:
F172145-REP-MOB-001 in Appendix B).
The acoustic data recorded for this source on the AMARs was of good quality with pulses clearly detectable above ambient sound levels.
8.5 Side scan Sonar Data
SSS data quality was monitored throughout the survey and deemed to be representative of what we see during standard geophysical survey. Data was recorded in both the HF and LF channels to the full extent of the 75 m range.
8.6 Parametric Sub-bottom Profiler Data
SBP data was monitored throughout the survey to ensure the headers were correctly
populated and shot point intervals were regular. Whilst the effects of marginal weather were apparent in some of the lines in the form of burst noise, the quality of the data was generally acceptable.
The acoustic data recorded for this source on the AMARs was of good quality with pulses clearly detectable above ambient sound levels.