SOP-028 SUB-BOTTOM PROFILER OPERATIONS PROCEDURE

Transcription

1 SOP-028 SUB-BOTTOM PROFILER OPERATIONS PROCEDURE Rev No. Issue Description Prepared Reviewed Approved Date 1 Re-issued for use JAL JPV GF 25 May 11 0 Issued for use JAL JPV GF 28 Feb 11 P1 Prepared for review JAL JPV JAL 16 Feb 11 File Reference: O:\Referenced_Documents\Survey Operations Procedures\SOP-028 Sub-Bottom Profiler Operations Procedure Rev. 1.doc Copyright UTEC International Limited, 2011 Unless explicitly stated otherwise, all rights including those in copyright in the content of this document are owned or controlled by UTEC International Limited. Except as otherwise expressly permitted under copyright law or by UTEC International Limited, the content of this document may not be copied, reproduced, republished, downloaded, posted, broadcast or transmitted in any way without the written permission of UTEC International Limited. MSF-001 Rev 1 Page 1 of 30

2 REVISION HISTORY Rev. Section Revision Description Date 1 All Document rebranded, no change to content 25 May 11 MSF-001 Rev 1 Page 2 of 30

3 TABLE OF CONTENTS Page No. 1 INTRODUCTION Purpose Scope Definitions and Abbreviations 5 2 RESPONSIBILITIES Survey Manager QHSE Manager Project Manager Operations / Technical Manager Party Chief or UTEC Senior Site Representative Survey Engineer Onboard Geophysicist Survey Team 9 3 HEALTH AND SAFETY 10 4 SUB-BOTTOM PROFILER OVERVIEW Overview Types of Sub-bottom Profilers System Components 13 5 MOBILISATION Pre-Mobilisation Checks Installation Hull Mount System Installation Over-the-Side Mount System Installation Boomer and Sparker System Installation Towed System Installation ROV Mounted System Installation AUV Mounted System Installation Recording System Pulse Test (for Boomer and Sparker only) Wet Test Recorder test Calibration and Testing 22 MSF-001 Rev 1 Page 3 of 30

4 6 SUB-BOTTOM PROFILER OPERATIONS Deployment Recovery 23 7 OPERATIONAL SAFETY General Winch Operations Deployment and Recovery Operations Towing Operations 26 8 DATA ACQUISITION AND QUALITY CONTROL 28 9 REFERENCES UTEC References External References APPENDICES 30 MSF-001 Rev 1 Page 4 of 30

5 1 INTRODUCTION 1.1 Purpose The purpose of this procedure is to detail the requirements and responsibilities for the calibration, installation, and operation of sub-bottom profiler equipment so that high quality sub-bottom profiler data is recorded. It is intended to ensure UTEC employ industry best practice and meet customer expectations. 1.2 Scope The procedure is to be followed by all UTEC personnel. It includes general information on sub-bottom profiler and detail of the types of equipment, equipment accuracies, safe installation and operation methods, and processing and reporting requirements including formulae to be used for calculations. 1.3 Definitions and Abbreviations Definitions Terminologies relevant to sub-bottom profilers are defined below: Band-pass Filter : Frequency cut-off filter that passes a range of frequencies unaltered while attenuating frequencies outside the range. The components of a band-pass filter include the Low-Cut (High Pass) Filter, the High-Cut (Low Pass) Filter. Bandwidth : A measure of the width of a range of frequencies, measured in hertz. Beam spreading : Divergence of sonar beam as a function of angle and distance from the transducer. Beam spreading results in decrease of resolution of the image at longer distances. Frequency : Number of cycles of a sound wave per unit time. Measured in Hertz. Generally 1 Hz = 1 cycle per second. Frequency has an inverse relationship to wavelength (see below). Horizontal Resolution Multiple Reflection : Along track resolution determined by ping interval and vessel speed over ground. Higher ping rates and slower vessel speed gives higher horizontal resolution. : Multiply reflected seismic energy, or any event in seismic data that has incurred more than one reflection in its travel path, and may interfere with or obscure the primary reflection from other horizons. Pulse Length : Physical length (in time) of one pulse along the direction of propagation. Measured in milliseconds. MSF-001 Rev 1 Page 5 of 30

6 Time-Variant Gain Time-Variant Filter Vertical Resolution Signal-to-Noise Ratio Two-way Travel Time : Time dependent amplification of received signal between outgoing sonar pulses : Time dependent band pass filtering of received signal between outgoing sonar pulses. : Minimum vertical distance necessary between two separate interfaces to distinguish them as separate entities on a seismic profile. Vertical resolution is a function of the seismic wavelength. : Measure of how much a signal has been corrupted by noise. It is defined as the ratio of the signal magnitude to the noise magnitude corrupting the signal. : Elapsed time for a seismic wave to travel from its source to a given reflector and return to the receiver at a minimal offset from the source. Wavelength : The spatial period of a wave; the distance over which a wave s shape repeats Abbreviations Abbreviations used in this document are defined below: AUV : Autonomous Underwater Vehicle CCTV : Closed Circuit TV CMG : Course Made Good PPE : Personal Protective Equipment ROV : Remotely Operated Vehicle SBP : Sub-bottom Profiler USBL : Ultra-Short Base Line HV : High Voltage AC : Alternating Current TVG : Time-Variant Gain TVF : Time-Variant Filter Hz : Hertz (unit of frequency) FM : Frequency Modulation ms : Milliseconds twtt : Two-way Travel Time MSF-001 Rev 1 Page 6 of 30

7 2 RESPONSIBILITIES 2.1 Survey Manager The Survey Manager is responsible for: Ensuring the Sub-bottom Profiler Operations Procedure is based on industry best practice and that the content of the procedure is regularly reviewed and revised where necessary, when improvements in technology or practice are identified; and, Ensuring that the Survey Team includes personnel competent to carry out the tasks involved in acquiring sub-bottom profiler data. 2.2 QHSE Manager The QHSE Manager is responsible for: Ensuring that the Sub-bottom Profiler Operations Procedure is adequately controlled with regards to review, revision and approval, and that the relevant version is available at the point of use; and, All relevant and related QHSE policies / documents are readily accessible to Project team. 2.3 Project Manager The Project Manager is responsible for: Ensuring that the Operations Manager is notified of the project requirements; Ensuring that all project personnel are aware of their responsibilities with regards to the Sub-bottom Profiler Operations Procedure; Ensuring that adequately certified equipment is supplied to the project to meet customer specification; and, Ensuring that any hazards associated with the tasks involved are adequately risk assessed and that project personnel are made aware of these hazards. 2.4 Operations / Technical Manager The Operations Manager is responsible for: Ensuring that all equipment despatched to the field are in good operating condition, with sufficient consumables and spares to complete the operation; and, Ensuring that adequately certified equipment is supplied to the project to meet customer specification. MSF-001 Rev 1 Page 7 of 30

8 2.5 Party Chief or UTEC Senior Site Representative The Party Chief or UTEC Senior Site Representative is responsible for: Ensuring that the Survey Team follow the requirements of the Sub-bottom Profiler Operations Procedure during operations; and, Advising the Project Manager when any deviations from the procedure is felt necessary due to changes in operational method, procedural inadequacy or change in project specific requirements. 2.6 Survey Engineer The Survey Engineer is responsible for: Ensuring that equipment is installed, tested and maintained in accordance with this procedure; Ensuring all calibrations or tests are conducted to meet project specifications; Deployment and recovery of sub-bottom profiler equipment; Ensuring that adequate levels of spares and consumables are mobilised to meet project requirements; Ensuring that Analogue and Digital data are logged and backed up according to procedure; Ensuring that the hard copy data rolls are properly labelled; Ensuring the appropriate logs are filled in completely; and, Assuming the Acquisition responsibilities of the Geophysicist when team does not include this discipline. 2.7 Onboard Geophysicist The Onboard Geophysicist is responsible for: The tuning of the sub-bottom profiler signal on the recording system(s); Ensuring that survey specifications are met; Ensuring the quality of the recorded data; Liaising with the Client Representative on matters regarding sub-bottom profiler survey operations; Liaising and coordination with other offline personnel during post-processing of the survey data; Quality control of the survey results prior to their despatch from the vessel; and; The interpretation of the sub-bottom profiler data (if required). MSF-001 Rev 1 Page 8 of 30

9 2.8 Survey Team All members of the Survey Team are responsible for: Ensuring that they follow the requirements of the Sub-bottom Profiler Operations Procedure during operations; and, Ensuring that they comply with all controls in place to protect the environment, health and safety of themselves and others. MSF-001 Rev 1 Page 9 of 30

10 3 HEALTH AND SAFETY Installation, testing, maintenance, deployment and recovery of sub-bottom profiler equipment are potentially hazardous activities. Prior to commencement of these activities a risk assessment shall have taken place to ensure that all hazards have been identified, the associated risk assessed and that all personnel are aware of the necessary control measures. MSF-001 Rev 1 Page 10 of 30

11 4 SUB-BOTTOM PROFILER OVERVIEW 4.1 Overview Sub-bottom profile systems are a towed or hull mounted sensor that generates energy pulse which can penetrate the seafloor up to a certain depth. The amount of penetration depends on the type of system being used. These can range from relatively shallow penetrating pingers, up to deeper penetrating sub-tow sparkers. Sub-bottom profilers can be put to a number of different uses, ranging from analogue pipeline surveys to rig site surveys. The deeper penetrating systems can be used for shallow gas investigation. Sub-bottom profilers have a range of applications including route surveys, course pipeline inspection, site surveys. Sub-bottom profiler surveys are an important tool in checking for near surface but non-visible objects. 4.2 Types of Sub-bottom Profilers Pinger There are four types of sub-bottom profilers which may be utilised by UTEC: Pinger, Chirp, Boomer, and Sparker. The type of sub-bottom profiler to be used during survey operations will depend on the specific requirements detailed in the contract document, the objectives of the survey, as well as the environmental conditions on site. The Pinger SBP is the most basic and currently the most widely utilized SBP in the market. It utilizes a piezoelectric transducer to generate a tuned single frequency pulse of between 2.0kHz and 12.0kHz range, but generally between 3.5kHz and 7.0kHz range. The Pinger SBP can achieve penetration below seafloor ranging between few meters to over 50 metres, dependant on the type of seafloor sediments. Pinger SBPs are capable of resolving stratigraphic boundaries down to a thickness of approximately 0.3m. The Pinger SBP is composed of a deck unit (Transmitter and Receiver, or combined Transceiver, dependant on make / manufacturer), transducer arrays (4 transducers on over the side mount / towfish, or a hull mount arrangement which can be configured to hold up to 16 transducers). Pinger SBPs may also be mounted on an ROV or AUV. The Pinger SBP (over the side mount and hull mount) are usually interfaced to a heave compensator / motion reference unit, which allows the sub-bottom profiler data to be compensated for heave and swell artifacts. MSF-001 Rev 1 Page 11 of 30

12 4.2.2 Chirp The Chirp SBP is similar in physical characteristics and operation to the Pinger SBP. The difference lies in that it operates around a central frequency that is modulated across a range of frequencies (frequency modulation), usually between 3kHz and 40kHz (as opposed to a single frequency for the Pinger). Chirp SBPs achieve similar penetration below seafloor to that of the Pinger, but are capable of resolving stratigraphic boundaries down to a thickness better than 0.1m. The Chirp SBP is composed of a deck unit (Transmitter and Receiver, or combined Transceiver, dependant on make / manufacturer), transducer arrays (4 transducers on over the side mount / towfish, or a hull mount arrangement which can be configured to hold up to 16 transducers). Chirp SBPs may also be mounted on an ROV or AUV. The Chirp SBP (over the side mount and hull mount) are usually interfaced to a heave compensator / motion reference unit, which allows the sub-bottom profiler data to be compensated for heave and swell artifacts Boomer The Boomer SBP is a low frequency SBP comprising an electromechanical source and a separate receiver. The Boomer SBP operates from 50J to 1000J at frequencies between 50Hz and 5000Hz (depending on source power setting, higher power = lower frequency). The Boomer SBP can achieve penetration below seafloor between 30m and 100m with a vertical resolution of between 0.3m and 1m, dependant on the type of seafloor sediments. The Boomer SBP is composed of a power supply, electromechanical source (mounted on a catamaran) and tow cable, and a multi-element single-channel hydrophone and deck receiver. Boomer SBP are surface towed, though some older models have option for sub-surface towed (no longer manufactured). There are two main types of boomer SBP, the standard High Voltage boomer models, and the Low Voltage boomer models (for use on inshore surveys) Sparker The Sparker SBP is a low frequency SBP comprising an electrical spark source and a separate receiver. The Sparker SBP operates from 300J to 12,000J dependant on the source configuration at frequencies between 50Hz and 4000Hz (depending on source power, higher power = lower frequency). The Sparker SBP can achieve penetration below seafloor in excess of 1000m with a vertical resolution of between 0.3m and 1m, dependant on the type of seafloor sediments. The Sparker SBP is composed of a power supply, electrical spark source (mounted on a catamaran, frame or similar) and tow cable, and a multi-element singlechannel hydrophone and deck receiver. Sparker SBP are mainly surface towed, with some deep towed sparkers (higher energy source) also available. There are several types of Sparker SBP, namely the standard catamaran mounted Sparker (various power output capacities, based on manufacturer), the squid sparker (low energy, light weight, high-frequency), the Delta Sparker (high energy, lowfrequency mounted on a triangular shaped frame) and the deep-tow sparker (high- MSF-001 Rev 1 Page 12 of 30

13 frequency, high-resolution Sparker system, towed at depth, which eliminates surface ghost, and provides ultra-high-resolution seismic profiles). 4.3 System Components Pinger and Chirp The main components of the Pinger and Chirp SBPs are as follows: Deck Unit Transmitter and Receiver or combined Transceiver, depending on manufacturer; Transducer array Configuration of the transducers are dependent on the mounting / deployment, 1 to 4 transducers on a towed Pinger / Chirp, 1 to 4 transducers on over the side mount, and up to 16 transducers for hull mount configurations; and, Heave compensator (for hull mount and over side mount configurations) Boomer and Sparker The main components of the Boomer and Sparker SBPs are as follows: Energy Source (electromechanical plate for the Boomer, and spark tips for the Sparker); HV Power Supply Unit; Multi-element, single channel hydrophone; and, Deck Receiver Ancillary Equipment In addition to the sub-bottom profiler the following ancillary equipment shall be used in conjunction with the main units: Data Acquisition and Processing system (i.e. CODA, SonarWiz and the like); Thermal Plotter (optional depending on client requirements); Cable Counter (for towed systems); Record Annotator (optional, dependant on recording / processing system used); and, External Trigger (optional). MSF-001 Rev 1 Page 13 of 30

14 5 MOBILISATION 5.1 Pre-Mobilisation Checks Prior to shipment to the vessel, sub-bottom profiler equipment will be checked and bench tested in the UTEC workshop by the Base Engineer: To confirm full operational status of the equipment a visual plus operational check of the system shall be carried out in the workshop. Each component of the system shall be bench tested and calibrated in accordance with the manufacturer s specifications: Power amplifiers, Print amplifiers, Paper drive motors, Interconnecting cables, Transducers, and Power Supply Unit (for Boomer and Sparker). The system shall then be assembled and an overall system test completed before shipping. These tests shall include all applicable spares. The Project Manager will confirm level of spares and consumables to be shipped with the SBP. 5.2 Installation Hull Mount System Installation of hull mount system will vary depending upon each individual ship. Some hull mounts are installed on a gondola underneath the ship, requiring hull penetration and dry docking. Other hull mounts are installed in a sea chest or water tank at the base of the ship, with transducers flush as possible with the ship s hull plating, not needing hull penetration. As the installation will be ship dependant, it is beyond the scope of this document to present a detailed discussion on installation of hull mount systems. 5.3 Installation Over-the-Side Mount System When installing a temporary or portable system the following should be considered: Usually an over the side pole is used for a temporary installation; The pole should be rigid enough for the vessel to manoeuvre at up to 3 knots; The Transducer should be 3m below the vessel in the deployed position; The use of stops and stays should be used to ensure that the pole returns to the same point after deployment; MSF-001 Rev 1 Page 14 of 30

15 A short adaptor pipe will usually be required to fit between the flange on the end of the pole and the transducer head; A non- conductive spacer and nylon bolt covers should be used to ensure that there is no metal to metal contact between the transducer head and the pole; Prior to installing the system ensure that all bolts, washers, adaptors, spacers etc are present and in good order; When attaching the head to the pole, it should be supported independently i.e. with a choke strop; Deployment and recovery should be planned and executed in clear manageable steps ideally a small davit and winch should be used to for deployment and recovery; Secure any bolts using sprung washers and loctite; Deck units (transmitters and receivers) must be placed in a suitably ventilated, dry, cool (air conditioned) workspace; Deck cables must be run properly in order not to pose a hazard top operations; and, The Pinger and Chirp units operate at high voltages (240 VAC), as such interfacing, testing and servicing of the unit should only be conducted by competent personnel, after a thorough risk assessment is performed. In order to reduce the number of over the side mountings on the ship, it is possible to mount the Pinger / Chirp SBP on the same pole as the USBL (or similar), on a split flange attached to the end of the pole. 5.4 Installation Boomer and Sparker System When employing a Boomer or Sparker system, the source is towed off one side of the vessel, while the hydrophone is towed on the opposite side of the vessel. Where possible, a boom is recommended to ensure both the source and hydrophone are not streamed within the wake of the survey vessel (thus degrading the quality of the data) Deployment System The type of deployment system varies from survey platform to survey platform, depending on available deck space, freeboard of the ship, etc. Source Normally, the Boomer / Sparker source would be deployed over the stern of the ship, possibly lowered with assistance of a davit, and towed off a pad eye on the stern quarter of the ship (weight of the system is not on the davit). A minimum of two persons would be required to control the deployment of the catamaran, while a third would need to hold on the cable during deployment. Once deployed, the catamaran is then guided on to the stern quarter of the ship and tied off. MSF-001 Rev 1 Page 15 of 30

16 Hydrophone The hydrophone is deployed in the opposite quarter of the ship to where the energy source is deployed. It may be tied off the stern quarter of the ship or (preferably) on a boom that ensures the hydrophone is deployed as much as possible outside of the wake of the ship Power Supply Unit The HV power supply units need to be installed in a suitably ventilated, cool and dry place in the ship, isolated from access by unauthorised personnel. It should also be situated such that the deck cable need not be overly long. The Boomer and Sparker Power Supply Units operate at very high voltages (up to 440 VAC / 12,000J), as such interfacing, testing and servicing of the unit should only be conducted by competent personnel after a thorough risk assessment is performed Receiver Unit Deck units (transmitters and receivers) must be placed in a suitably ventilated, dry, cool (air conditioned) workspace. Deck cables must be run properly in order not to pose hazard top operations. 5.5 Installation Towed System The preferred deployment arrangement for towed sub-bottom profiler is from an A- Frame, a davit, or crane fitted with a counter sheave or cable out indicator. On small boats, the sub-bottom profiler may also be fitted on to an over-the-side mount or towed from a soft-tow cable Deployment System The type of deployment system varies from survey platform to survey platform. Different types of deployment include, but are not limited to the following: A Frame, Davit, and Crane. A Frame If an A Frame is available for use on the survey vessel, this should be tested operationally. Load and MPI testing should be conducted as required. If an A Frame is to be installed on the survey vessel, the ship s master should be consulted prior to a decision being made on the size and location of the A Frame to ensure this has no effect on the ship s stability. Deck welding over fuel tank is not permitted. The vessel Chief Engineer or Master shall confirm deck strength at weld points. Once a suitable A Frame is sourced and a location identified, onboard the survey vessel, installation of the A Frame should be undertaken by competent MSF-001 Rev 1 Page 16 of 30

17 persons. The A Frame should be fixed on deck in the correct manner. Where appropriate and possible, load and MPI testing should be conducted. Davit If a fixed davit is used, this must be located in a suitable point along the stern or side of the ship, and allow the sub-bottom profiler towfish to be deployed clear of the survey vessel s hull / sides to prevent damage to the towfish and the tow cable (through banging, and / or chaffing). Load and MPI testing should be conducted as required. Deck welding over fuel tank is not permitted. The vessel Chief Engineer or Master shall confirm deck strength at weld points. Crane Winch If a crane is used for deployment of the towfish, ensure that the crane is rated and operational, the crane operator is certified. Coordinate with the crane operator for the deployment and recovery procedures. Ensure that the position of the crane would allow free running of the sub-bottom profiler tow cable. If towing from the crane, ensure the crane can be locked into position one the tow has started, e.g. confirm the crane position does not slip during the tow. Sheave Block Regardless of the type of deployment system used (crane, davit, A Frame), a sheave block should be used to safely run the tow cable. Preferably the sheave block is a calibrated cable counter type. All shackles in the rigging must be certified. The sheave block should be suitable and rated to the task. It should be free to allow smooth running of the tow cable. The sheave block should be mounted securely on the deployment system by a competent person. The winch should be in good working order and maintained properly. The winch should be located in a suitable location, which will satisfy the following considerations: Allow safe access for the operator; Have a clear run for the cable from the winch to the sheave block, with minimal obstruction; and, Allow hoses and/or cables to be run safely. The winch should be fixed on deck in the correct manner and should be properly earthed. Load and MPI testing should be conducted as required. MSF-001 Rev 1 Page 17 of 30

18 Deck welding over fuel tank is not permitted. The vessel Chief Engineer or Master shall confirm deck strength at weld points. The deck cables and hoses should be secured properly, and if possible enclosed in proper cable runs and where they may pose a hazard (trip hazard, head hazard), clearly marked as such. Winches have different power requirements. Winch power supply must be checked to ensure it is correctly rated and connected. A qualified engineer must undertake installation of electrical system. Electrical systems must be correctly earthed. In case the winch is hydraulic / electro-hydraulic, a qualified engineer must undertake installation of the hydraulic system. Remote Winch: If a remote winch is used, ensure the following as a minimum is done: A CCTV camera or similar should be installed which will allow the operator an un-obstructed view of the winch and deck in front of the winch, where the cable passes. If required, an additional CCTV camera should be installed allowing an un-obstructed view of the launch / deployment system ( A Frame, Davit, Crane) to ensure that the sub-bottom profiler towfish is not snatched through the sheave block during recovery; Appropriate safety measures must be taken including installation of warnings / visual warning devices (i.e. hazard signs, flashing lights, and the like); All onboard personnel are made aware / constantly reminded the winch may operate without warning (during project start-up briefing, toolbox meetings, HSE meetings); and, A safety stop button must be located at the winch and remote control. If possible, the back deck area between the winch and deployment system should be declared off-limits to all non-essential personnel during operations. If anyone needs to work in the area, then the sub-bottom profiler operator needs to be informed prior to working in the area. Safety Measures: Toolbox meetings will be help prior to every launch and recovery operations. Appropriate warning signs / warning devices, meeting international standards must be in place. These should be clear and easily understood. If possible, the working area close to the winch and around the tow cable should be declared off-limits to non-essential personnel during survey operations, of whenever the sub-bottom profiler is deployed. The dangers inherent in the sub-bottom profiler set-up must be highlighted during the project kick-off meeting, and everyone should be reminded during risk assessments, toolbox meetings and safety meetings. Where possible, a proximity cut-off switch should be included on the outboard side of the sheave. MSF-001 Rev 1 Page 18 of 30

19 5.5.3 Tow Cable The tow cable should be marked at discrete intervals (i.e. 5m or 10m) to allow the cable length deployed to be determined visually Towfish The towfish should be installed, interfaced and set-up as per manufacturer s specification. The integrity of the pigtail / connector at the end of the tow cable should be checked, to ensure no corrosion or leakage is observed. When not in use, the towfish should be secured on deck, or another suitable location for safekeeping. All equipment spares shall be placed and secured in dry storage on the survey platform. Equipment faults and defects are to be reported using company procedure Towfish Tracking (Optional) Typically, a USBL (or similar) acoustic positioning is used to locate the sub-bottom profiler towfish while on survey. If a USBL (or similar) acoustic positioning is used, the distance from the transducer to the sub-bottom profiler towfish should be measured as accurately as possible, and the value entered in the logging system to ensure that the correct position of the sub-bottom profiler towfish is logged. Set-up and calibration of the USBL system shall be in accordance with the USBL Procedure - SOP Manual Layback In some cases, a USBL acoustic positioning system is not used (either due to client requirement or impracticality). When this is the case, manual layback calculations are required to allow the position of the sub-bottom profiler tow fish to be logged. The position of the tow fish is calculated using Pythagorean Theorem taking in to consideration 3 parameters: i) Layback (amount of cable paid out), ii) Course made good (CMG), and iii) Depth of tow fish (calculated by subtracting tow fish height from water depth and adding height of the tow point above sea level). MSF-001 Rev 1 Page 19 of 30

20 Tow point height (x) Sea surface Tow fish Depth (d) Tow fish height (h) Layback (L) Water Depth (W) Sea floor Most of the modern navigation systems have the capability to calculate and log tow fish position upon input by the operator of cable. 5.6 Installation ROV Mounted System When installing on to an ROV, the transducers should be fitted low on the vehicle and aligned with the vehicle heading. Ideally, the transducers should be acoustically isolated from the ROV. The line of sight from transducer should be clear of obstruction by parts of the vehicle. The transducers vertical alignment should be checked using a precision inclinometer. The system needs to be interfaced and powered up and tested prior to vessel arriving at the work location. 5.7 Installation AUV Mounted System The installation / mounting of the SBP on to the AUV will vary depending on the type of AUV used. On the Gavia AUV, the SBP is a module that is attached to the system, as with other modules. This is performed per Gavia standard procedures. Refer to Shallow Water AUV Operations Procedure - SOP-029 and Gavia AUV Operating Manual. 5.8 Installation Recording System The recording system should be installed, interfaced and set-up as per manufacturer s specification. The recording system should be located in a suitable location on the ship, close enough to the winch / deployment system so as not to require a long deck cable. There must be enough bench space to accommodate the topside equipment, and allow the operator free, unobstructed movement. MSF-001 Rev 1 Page 20 of 30

21 5.9 Pulse Test (for Boomer and Sparker only) The output pulse of sub bottom profiler shall be monitored with the source at shallow depth and with a suitable calibrated hydrophone (not older than 12 months since last calibration) and storage oscilloscope. The hydrophone should be positioned at a distance of one to two metres directly below the centre of the transducers, the exact distance shall be measured and entered in the calculations. Since the beam width reduces for higher frequencies, the positioning of the calibrated hydrophone is critical for these frequencies. All measurements are to be undertaken on the raw, un-filtered signal (5kW input power), and the sub-bottom profiler source shall be evidenced in producing a stable outgoing signal characterised by the following parameters: The source level derived from the largest peak to peak amplitude of the pulse train shall be in excess of 0.1 bar metre for the 3.5kHz and 5.0kHz operating frequencies (using pulse lengths of the electrical signal to the transducer related to the frequency of transmission); The source level derived from the largest peak to peak amplitude of the pulse train shall be in excess of 0.4 bar metre for the 14kHz operating frequency (pulse length of the electrical signal to the transducer to be related to the frequency of transmission); The pulse length (measured from the beginning of the pulse train [typically 3-5 cycles] to the end of the pulse train but excluding any reverberations) shall be less than 1.5ms for the 3.5kHz and 5kHz operating frequencies; The pulse length (measured from the beginning of the pulse train [typically 5 cycles] to the end of the pulse train but excluding any reverberations) shall be less than 1.0ms for the 14kHz operating frequency; and, The peak to peak amplitude of any reverberations after the initial pulse train shall be less than 1/8 of the largest amplitude of the initial pulse train Wet Test On completion of the deck checks the system shall be deployed and wet tested. A sea trial shall be carried out at the first opportunity, which should include: Testing of any USBL positioning of the tow fish; Testing interfacing to the online Navigation suite and to any annotation system; and, Testing of frequency and range setting to determine they are adequate for intended survey requirements Recorder test Thermal line recorder (if used) shall be checked at varying sweep speeds and that the annotation of the paper records operational and legible. MSF-001 Rev 1 Page 21 of 30

22 Paper record annotation shall be configured to provide optimum annotation interval for task/project and with minimum of over-writing. Annotation shall include the following: Date and time, Line number, Start and End of line, KP and DCC, and Cable out Calibration and Testing Interface Test An interface test shall be performed on all components of the sub-bottom profiler system once they are interconnected. As a minimum, the following need to be checked: Sea Trial Communication between signal processor and towfish (via deck lead, and via full system (through winch or ROV); Communication between signal processor and recording system; and; Communication between navigation system and recording system (ensure time stamp, position (easting and northing), heading, course made good, line name, etc. are received by the recording system in proper string format). Upon completion of mobilisation, preferably prior to arrival on location, a sea trial is to be carried out. The sea trial should include as a minimum the following: Testing interfacing on the on-line system computers; Testing of the range and frequency settings to ascertain the best configuration to meet the survey requirements; Testing of the USBL positioning (if any) of the towfish; and, Setting-up the proper acquisition, processing and logging parameters on the recorder. MSF-001 Rev 1 Page 22 of 30

23 6 SUB-BOTTOM PROFILER OPERATIONS This section deals with towed operations for ROV mounted SBP see ROV Sensor Installation and Integration Procedure - SOP Deployment This section deals with towed operations, for ROV mounted SBP see ROV Sensor Installation and Integration Procedure - SOP-010. Deployment of the sub-bottom profiler system should be in line with any generic and onboard risk assessments, the vessel s own safety procedures, and toolbox talks, which are conducted for this task. As risk assessments and safety procedures will vary between equipment installations, no specific procedures are included in this manual. Prior to deployment of the towfish, the bridge and online navigation should be informed of the intent to deploy the towfish. Constant communication between personnel on the back deck and the bridge / online navigation should be in place throughout the deployment process. The towfish should be deployed in a steady and safe manner. The personnel assigned to deploy the towfish overboard should follow proper safety procedures for over the side work. During deployment of the towfish, the survey vessel should sail at a constant heading, and at a constant speed of approximately 3 knots. The same heading should be maintained until the towfish is fully deployed in the water. Once the towfish is in the water, the bridge / online navigation should be informed of such. In case the towfish is deployed from an over-the-side mount, the survey vessel should be stationary, until deployment and securing of the pole in place is completed. 6.2 Recovery Recovery of the system should be in line with any generic and onboard risk assessments, the vessel s own safety procedures, and toolbox talks, which are conducted for this task. As risk assessments and safety procedures vary between survey vessels, no specific procedures are included in this manual. Prior to recovery of the towfish, the bridge and online navigation should be informed of the intent to recover the towfish. Constant communication between personnel on the back deck and the bridge / online navigation should be in place throughout the recovery process. During recovery of the towfish, the survey vessel should sail at a constant heading, and at a constant speed of approximately 4 knots. Whilst recovering the towfish, if there is less than 50m of cable-out left, the operator should not use the remote, MSF-001 Rev 1 Page 23 of 30

24 rather should operate the winch from the winch control station, to ensure the towfish is not snatched through the sheave block. The towfish should be recovered in a steady and safe manner. The personnel assigned to bring the towfish onboard should follow proper safety procedures for over the side work. Once the towfish is on deck, the bridge / online navigation should be informed of such. MSF-001 Rev 1 Page 24 of 30

25 7 OPERATIONAL SAFETY 7.1 General Safety is paramount to all activities as such, everyone is expected to keep a positive safety culture no matter what or where the work is. Regardless of the task involved, the following generally apply when working offshore: All personnel must be properly briefed prior to undertaking any task. If the task is new, a Risk Assessment using form MSF-033 must be undertaken; All persons working on the back deck must wear appropriate Personal Protective Equipment (PPE), including but not limited to safety boots with non-slip soles, gloves and any other safety equipment relevant to the task at hand; When working on the back deck, never work alone, and always ensure you are in view of a colleague; Only properly trained / competent personnel are allowed to operate equipment; i.e. crane operators are the only ones allowed to operate the cranes, etc.; Communications shall be established between the Survey Engineer, Vessel Helmsman and Online Surveyor. At all times during SBP operations, all three personnel on shift shall be in radio contact; Communications must be established and maintained between personnel working on the deck, the bridge and the instrument / survey room. At all times during back deck operations, all personnel on shift shall be in radio contact; and Preventive maintenance must be carried out regularly by competent persons on all equipment. Any such maintenance should be conducted in a safe manner; DON Ts The following should NEVER be done while under operations: NEVER stand under, or in the vicinity of a tow wire in motion or under tension; NEVER stand over or on a winch wire. Note that weather conditions and vessel roll may cause a wire to move unexpectedly; NEVER stand in the path that a wire could take if it should part under load; NEVER stand in wire loops on deck. Sudden unexpected load or parting of winch wire has KILLED people stood in wire loops; NEVER handle a wire under tension or a wire that is trapped; NEVER use winches for man riding unless it is specifically designed and marked for such purpose and the operation has been agreed by the Company and a specific procedure issued; and, NEVER lean overboard without safety controls in place. MSF-001 Rev 1 Page 25 of 30

26 7.2 Winch Operations Electrical Safety Some electric winches operate at high voltages (380v / 440v three phase), reasonable precautions should be implemented to reduce the risk of electrical shock. Only properly rated, good quality cable must be used for the supply cable. Should there be any minor damage to the supply cable, the system must be isolated immediately, and the damage repaired. If there is any damage other than minor damage to the cable, then the cable should be immediately withdrawn from service, and replaced. The electrical system should also be properly earthed, to allow protection devices to function properly Hydraulic Safety Some winches are operated by hydraulics or a combination of electro-hydraulics. In hydraulic systems, there is always the presence of hazards associated with highpressure hydraulic oil. When testing and using hydraulic equipment, all leaks should be sealed properly and it is vital to avoid high pressure oil to come in to contact with the body. Additionally, any hydraulic oil spilled should be cleaned up properly as soon as possible, since these have the potential as slip and fall hazards as well as pollution. 7.3 Deployment and Recovery Operations During deployment and recovery operations, safety of personnel is of paramount importance. All proper safety precautions must be taken, and correct PPE utilised. If the deployment and / or recovery of the towfish require one or more personnel to lean over the side, correct PPE including safety harnesses must be utilised by the relevant personnel involved. Always watch the tow cable, the item being recovered / deployed and the spooling of the wire on the drum. If you cannot observe all these parts of the operation, find a colleague to watch for you whilst in close communication with you. 7.4 Towing Operations Operating in areas of high vessel traffic / fishing activity When operating in areas of high vessel traffic, it is important to keep a close watchful eye on the environment surrounding the survey vessel, especially along the proposed survey line. Where possible a lookout should be posted to keep an eye out on other shipping activities, as well as possible obstructions in the sea, such as fish traps and fishing nets. Close communication should be maintained between the lookout, the bridge / navigation station and the survey control room. MSF-001 Rev 1 Page 26 of 30

27 7.4.2 Operating in areas Rough Seabed When operating in areas of rough, highly undulating seafloor, a close eye must be kept on the vessel echo sounder. The sub-bottom profiler winch operator must anticipate any shoaling which could impact on the towfish, and recover or deploy the tow cable accordingly Operating in close proximity to known surface and sub-surface structures Where operations are required in close proximity to known surface and sub-surface structures, the following as a minimum must be conducted: Vessel and site specific procedures / work instructions for working within any 500m safety Zone must be drawn up, and disseminated to all concerned; Safety briefing of all concerned personnel, including Master, Party Chief, Client Representative(s), Bridge Officers on watch, Online Navigators on watch, Survey Engineers on watch. The vessel and site specific procedures / work instructions must be discussed, and a general consensus reached on the practicality of the required approach; Communications between the survey vessel and the offshore installation must be established well in advance of any activities in close proximity of surface or sub-surface structures; Operations should only be conducted during daylight hours, and in conditions which will allow the bridge officers to accurately judge distances to surface structures; Survey operations must be performed where nothing approaches closer than 50m from any structure, unless expressly permitted in writing by the onboard Client Representative(s) and concurred by the relevant offshore installation manager(s); It is important to assess the surface and sub-surface currents prior to attempting sub-bottom profiler survey operations close to these structures. There may be instances where the towfish is feathering closer to the structure than the survey vessel, which may require the runline to be adjusted accordingly; and, Moorings and anchor lines shall be plotted on the navigation display, or if unknown, the bridge will advise of any buoys in the survey area. MSF-001 Rev 1 Page 27 of 30

28 8 DATA ACQUISITION AND QUALITY CONTROL Data quality shall be the responsibility of the Geophysicist or, if required the Survey Engineer. The following data integrity checks shall be performed during data acquisition and logged using form MSF-096 Sub-bottom Profiler Log. Pulse rep. rate / Sweep time / Frequency settings correct, any change annotated on record / log; In case of fish tracking check if the correct transponder is selected; Fix annotation clear to read; Quality of the analogue records and relevant scale and paper speed set; Any means of data correlation applicable shall be used to verify the integrity of the data obtained. (E.g.; existing pipelines, previous survey data, etc.); If necessary reduce survey speed and/or direction to improve record quality (e.g. during marginal weather conditions); and, Data coverage over desired area achieved. Data acquisition shall not continue if the data has deteriorated to an extent where it is not acceptable for the purpose for which it is intended. The recorded analogue records (if in use) shall be clearly annotated at both ends of the records. The following minimum information shall be recorded: Job number, Vessel name, Location, Date and time, Line and fix numbers, System/Equip settings, Cable out, Operators name, and Client. MSF-001 Rev 1 Page 28 of 30

29 9 REFERENCES 9.1 UTEC References Document Title USBL Procedure ROV Sensor Installation and Integration Procedure Shallow Water AUV Operations Procedure Risk Assessment Template Sub-Bottom Profiler Log Reference SOP-005 SOP-010 SOP-029 MSF-033 MSF External References 1. Refer to Gavia AUV Operating Manual. MSF-001 Rev 1 Page 29 of 30

30 10 APPENDICES None MSF-001 Rev 1 Page 30 of 30