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Development of a passive location and identification sonar tag for assisting in the laying, installation and long term monitoring of subsea cables and pipelines

Periodic Report Summary 1 - SONATAG (Development of a passive location and identification sonar tag for assisting in the laying, installation and long term monitoring of subsea cables and pipelines)

Project Context and Objectives:
Expansion of offshore oil & gas fields is inevitable, requiring significant investment in new pipelines and other infrastructure. Furthermore, due to the significant growth in offshore wind farms & telecommunication systems, several thousand kilometres of newly installed subsea cables will be required for both power & network connections. With the increase in new applications it is becoming critical that such underwater infrastructure is properly managed over its lifetime, to maintain safe, reliable & mapped sub-sea assets.
The SonaTag project will develop a novel low-cost, passive sub-sea tag capable of determining position& location of the infrastructure through a unique identification response and a custom designed sonar system. SonaTag will therefore offer cable & pipeline (CP) laying contractors a means to greatly reduce the cost of operations, thereby ensuring its rapid adoption into this market sector. Furthermore, additional benefits to downstream stakeholders, such as Inspection Maintenance and Repair (IMR) crews, as they will have the ability to locate and uniquely identify these vital assets, quickly & safely.
The SonaTag system will provide a robust solution for long-term lifecycle tagging by achieving the following objectives:
1) Specialised sonar with transmit power adequate for deployment (220 dB) at transmit end to achieve operational accuracy of +/- 0.1m @ 10m to 1000m range;
2) The ability to detect range & position of tag in 5secs @ 1000m and 2 secs @ 10m from sonar transceiver;
3) Inert tag device with detectability in relatively high noise environments i.e. ‘sea floor’.
Using this solution the project expects to overcome the issues of unmanaged critical sub-sea infrastructure and demonstrate the reduction in operational and maintenance costs of high capital assets.

Project Results:
Using the experience within the project consortia a system performance specification has been defined to meet the desired project objectives. To assist in the specification process a due diligence analysis was conducted to identify any new market entry products in terms of hardware, software and/or systems to ensure our freedom to operate (IP whitespace) was still valid.
In addition, a specification for the SonaTag sonar target has been developed, including investigations of target structure and pulse characteristics, considering geometry, coupling and frequency; the identification of optimum method/algorithms for 3D tracking and the creation of a computer simulated model of the tracking system have been performed.
A literature review of relevant research has been carried out in order to identify a qualitative relationship between some design parameters relating to the SonaTag. Based on these observations and discussions between the consortium members, three initial design configurations, with four design parameters, have been defined.
A finite elemental analysis model has been created using Ansys™ multi-physics software to consider the time and frequency responses of the SonaTag. A number of refinements were carried out to improve the accuracy of this model beyond +/- 10% accuracy which was originally obtained. However following a period of evaluation it was concluded that the limitations of this modelling approach and software would prohibit the accuracy needed to precisely model >20 target devices. The outputs of this work were consequently used to provide design data for an empirical test programme which was adopted as the preferred approach to identify a range of unique SonaTag devices. Environmental effects on the SonaTag have also been analysed and the subsequent response to a range of pulse profiles has been considered in the prototype design specification. Based on the model & empirical test data, early indications of possible performance constraints of the sonar hardware and software have been identified and considered in parallel with the development of the sonar target (tag).
Consideration of suitable materials for the SonaTag device has focused on the key physical, chemical, environmental and acoustic properties required. The manufacturability of the tags and their viability for mass production has also been considered. Based on the available data and initial observations, a selection of potentially suitable materials for the SonaTag shells and cores has been identified. This has influenced the design and manufacture of an initial set of prototype tags that are currently undergoing acoustic performance tests at Novamina and will allow the effect on sonar response of the initial design configurations to be assessed. The results from testing programme will be used to guide the further development iterations in Period 2 of the project and also the selection of transducer for the sonar development work.
Within the SonaTag development program a sophisticated software platform and graphical user interface is being created to provide real time monitoring and graphical positional locations to the user. The software algorithm is designed to interpret the acoustic signals, filter the noise and transpose this into accurate location information based on the operational environment. A first generation GUI has already been produced and will be evaluated once data becomes available from the sonar development and tag testing programme

Potential Impact:
Current solutions for asset location & position fall short of the user requirements and as such open an opportunity for SonaTag to fill the void within the sub-sea asset install/management sector. Our programme of work has been designed to create the specific RTD results that will enable the project team to demonstrate the benefits of the system & its operational performance. The RTD programme strategically divides the system development into the following logical steps areas;
1. SonaTag system overall specification and design architecture
2. SonaTag design and device prototype
3. Sonar system hardware and design architecture
4. Sonar system communications interface and GUI software
5. Integrated SonaTag and sonar system
The SonaTag project will develop a complete end-to-end prototype system solution for marking of cables and pipelines. This will be transferred from the RTDs through specification documents detailing the equipment design, operation, expected performance, manufacturing considerations and any generated IP.
On achieving our objectives the CP operators & sub-sea support services will benefit from greater granularity of asset location and identification of the specific asset based on its acoustic response. The delivery of the SonarTag system to our customers will greatly streamline their CP laying operations by removing the need for expensive support vessels and improve the efficiency of the trenching machine used to bury the CP. Furthermore, many other stakeholders will benefit from this innovation through the lifetime of the CP.
The Project team recognised the importance of dissemination activities and created a brand image for SonaTag at the earliest opportunity, to help identify the project and its application. A logo has been created and applied to project documentation, literature, promotional material and finished product to give a distinctive and consistent visual identity. The logo design conveys the key elements of SonaTag: a physical device (the sphere) with an internal geometry, an acoustic reflection on one side comprising “bar-code” features, and a name flag.
The partners will disseminate the results of the project at various trade fairs, seminars, websites & through other media such as video, brochures and VIP events.
Following the successful development of the project IPR and its corresponding protection methodology will include:
• Patentable Technology:
1. Ultra Short BaseLine (USBL) sonar for acoustic tag ranging and positioning sensing;
2. Tunable acoustic tag with unique identification characteristics;
3. The exact materials contained in the tags and methods of tag production;
• Design Rights: User interface software for 3D location of underwater tags;
• Software Copyright: The embedded software within the Sonar System
• Trademark: SonaTag™

List of Websites:
http://www.sonatag.com/