The 2024 deployment

In 2024, funded by the US National Academies of Science, Engineering, and Medicine Gulf Research Programme and led by a team of scientists from the University of Rhode Island, five Sonardyne Origin 65 units were deployed alongside the original Sonardyne CPIES in the Gulf of Mexico (depth range of 1,800 – 3,200 m) for an initial 18-month measurement campaign.

Both the Origin 65s and CPIES have integrated acoustic modems enabling high-speed (up to 9,000 bps) acoustic telemetry to support wireless retrieval of data by an uncrewed surface vessel (USV) in addition to remote control of the instruments.

Despite similar telemetry capability, the volume of data generated by Origin 65 compared to CPIES is much greater, and therefore limited acoustic bandwidth presents a challenge when looking to transfer this substantial data via acoustic telemetry.

This is where Origin 65’s Edge onboard data processing capability comes into play to condense the bulky raw data into small packets of actionable information, easily exportable via the acoustic modem.

The five Origin 65 units were deployed with an Edge application (app) installed to perform combined onboard processing of the ADCP and PIES data. More specifically, the Edge app implemented a custom algorithm that produced an hourly compact (24 bytes) binary output containing a timestamp, the mean current speed and bearing in six depth-bins above the bottom, plus the mean of the PIES results.

The beauty of the onboard data processing was apparent during planned USV visits, where it took less than 20 minutes to acoustically harvest more than two months’ worth of data

An assessment was conducted whereby the integrated acoustic release on one of the Origin 65 instruments was triggered after 66 days of deployment to allow recovery (Figure 1) of the device and complete data download for a thorough evaluation. This instrument was located in a water depth of 2,142 m.

Figure 1: Retrieval of the Origin 65 aboard the R/V Pelican.

Pies

The PIES portion of the Origin 65 performed consistently (Figure 2). Periods of increased scatter in the sound speed measurements are observable, but these are a result of higher ambient noise levels (pretrigger RMS), which correspond to higher sea states (local wave activity is a dominant source of acoustic noise given that in higher sea states the surface return from the PIES chirp is more spread out).

Figure 2: PIES sound speed and ambient noise (pretrigger RMS) measurements for the  deployment. The bottom plot compares ambient noise (pretrigger RMS) to the level of local wave activity using wind speed (as recorded by station Green Canyon 338, 124 km to the WNW of the deployment site) as a proxy for sea state.

ADCP

Velocity data demonstrates expected current behaviour (Figure 3), with velocities much larger in the Eastward and Northward directions than in the upward direction. The lack of significant apparent velocity in the vertical direction indicates that there is no systematic bias in the beam-frame Doppler velocities.

In addition, the observed velocity signals (large blue and red patches) vary on timescales between days and weeks, which is expected.

Of particular interest, it can be seen around 6th June, the prevailing current changed from South-Easterly to North-Westerly over the course of around two days.

This corresponded with a sudden increase in scatter density, thought to be an indication that the seabed was disturbed by the changing current.

Figure 3: Components of the Earth-frame velocities for the 66-day deployment (60-ping ensembles).

Low scatterer concentration in the deep waters (>2000 m) of the Gulf of Mexico reduced the effective profiling range of the Origin 65 from its achieved maximum range of > 800 m. However, with a sufficiently long averaging period it can been seen that the current velocity signal is present for the entire 800 m range of the Origin 65 (Figure 4).

Figure 4: Comparison of 24-hour averages of Eastward current velocity for different altitude bins. Performing increased averaging shows that a consistent current velocity signal is exhibited across the 800 m range of Origin 65.

“Our collaboration with the University of Rhode Island has been instrumental in augmenting our PIES technology in the form of Origin 65, a combined ADCP and PIES, for oceanographic study of geostrophic currents fields like that found in the Gulf of Mexico. We’re delighted to see Origin 65 being applied in this vital study, and by extension, to be able to support research efforts to improve and extend forecasting of the LCS and LCE behaviour with the accuracy desired. We look forward to continuing our relationship with the University of Rhode Island, and to seeing further successful USV data harvests from the Origin 65 units over their deployment period in the Gulf of Mexico.”

Michelle Barnett, Business Development Manager – Ocean Science, Sonardyne

What’s more, evidence of diel plankton migration is apparent with the repeated appearance and disappearance of a scattering layer between 500 m and 800 m height above the bottom. This pattern has a period of roughly 24 hours with the scattering layer clearly visible in daylight hours, as is consistent with the cycle of diel vertical migration observed ubiquitously in aquatic systems throughout the world.

This is nicely demonstrated in cross-correlation data, where values increased to around 80% on a daily cycle in response to the plankton migration (Figure 5). This cross-correlation data helps to indicate the effective maximum range of the system of around 800 m.

Figure 5: An excerpt (4 – 7th June) of unaveraged cross-correlation data for each of the four beams of the Origin 65 demonstrating a clearly observable diel vertical migration pattern. The lower plot represents the local time, with the colour being a function of the local solar altitude.

“This suite of instrumentation and platforms will help refine predictive tools for future applications in the Gulf. Looking ahead, the combination of Sonardyne Origin 65 current profilers and adaptive data-harvesting technology opens the door for long-term deployments in deep water – anywhere in the world. This is very exciting: we could access remote and critically important regions supporting sustained observations and advancing science.”

Professor Kathleen (Kathy) Donohue, Professor of Oceanography, University of Rhode Island

What’s next?

Two successful data harvests by a SeaTrac SP-48 USV equipped with a Sonardyne HPT 7000 L transceiver head have already been conducted. A third data harvest is scheduled for the end of July and the instruments will be recovered in September 2025. Keep an eye on our website and social media for further information about this and the data captured.

If you have an operational challenge for Origin 65, or any other Sonardyne product, please contact us.

Origin rewrites the story of your relationship with an ADCP

Our Origin family of ADCPs represent the latest in cutting edge underwater profiling technology. Able to analyse mean currents, waves and turbulence, and integrate with external sensors to provide pH levels, temperature and other data, Origin delivers comprehensive, reliable and timely data sets for your underwater operations.

With on-board Edge data processing and built-in acoustic modems, Origin can also process and deliver your data in almost real-time. This data is delivered in conventional PD0 format as standard but can be programmed to present results in our exclusive A-gram and B-gram formats, giving you up to 10 x greater spatial resolution detail.

Available in two models, Origin 65 for deep water profiling and Origin 600 for near and inshore waters, there is an Origin ADCP to suit your operation.

Why should you invest?

Origin ADCP family gives you the data you need, at a level of detail not available anywhere else on the market. Their ability to integrate with third party sensors unlocks additional capability and protects your investment.

Rechargeable batteries in Origin 600 give you rapid redeployment times as the unit can be recharged on the back deck whilst data is being downloaded before it’s returned to the seabed. Depending on your programme requirements, Origin 65 can operate for up to two years on the seabed before needing to replace its batteries.

Whichever size suits you best, they are both compatible with our Ranger 2 USBL equipment so you can harvest data and update your operation schedules mid-mission.

The challenge

Out of straightness (OOS) surveys are used for acquiring information about the vertical and horizontal configuration of offshore pipelines. They provide operators with information on the presence or otherwise of buckles and bending in a pipeline, which may be engineered or not, and require monitoring during the operational life of the pipeline or flowline asset.

Fugro have been conducting OOS surveys on pipelines for major energy companies in Australia for many years. These surveys were conducted using a Norbit WBMS Narrow Multibeam echo sounder mounted on a Fugro inspection class ROV deployed from Fugro’s 12m Blue Essence® USVs, Maali and Kwilena.

ROV missions along pipelines can be erratic and unreliable due to the distance between the transceiver (USV) and transponder (ROV) when using just USBL positioning. For Fugro’s OOS survey customers, highly accurate data is essential. This has led to their requirement for the highest accuracy navigation and imaging available to the small ROV.

Fugro set us the challenge to provide a navigation solution that would enable the customer requirements of high-quality data using a small ROV. We worked with Fugro to trial SPRINT-Nav Mini and demonstrate the capabilities of the system.

The results

Fugro utilise SPRINT-Nav Mini data within the ROV command and control software, Starfix® navigation, including their Camblock Vision based augmented reality system, and for processing MBES data. In the case of MBES processing, they are also conducting pipeline OOS surveys to a maximum depth of 200 metres.

The images below show some example data Fugro has gathered with MBES positioned using SPRINT-Nav Mini and post processed with our Janus software. Janus is our quality control and INS post processing software. It allows quick and easy data editing, post-processing and data export. Find out more about Janus here

If your offshore operations are also reliant on fast, efficient and accurate data to keep your business competitive in an ever-changing marketplace, take a look at our full range of navigational products here.

The challenge

A supermajor international energy company, with production infrastructure in more than 2,000 m (6,500 ft) of water depth, wanted a single subsea leak detection system that could be permanently installed to detect and localise, within seconds, oil or gas leaks across a wide area of its subsea infrastructure.

Existing sonar-based solutions are mostly based on sensors attached to subsea assets to detect leaks at specific or very localised locations, i.e. within a few metres. Alternative, non-acoustic, systems rely on anomalies in production data rates, which can be challenging should the leak occur upstream of the monitoring device.

At worst, leak detection relies on viewing the leak at the sea surface in the form of an oil-based sheen – when it’s already too late. This option is also limited when it comes to detecting leaks at gas producing fields and offshore carbon capture and storage (CCS) sites.

With a globally significant installed and aging asset base, as well as new infrastructure in the form of offshore CO₂ and hydrogen transport and storage, there’s increasing interest in alternative leak detection technologies that can operate autonomously and sustainably over wide areas in all water depths.

The solution

Developed by Wavefront Systems and manufactured and commercialised by Sonardyne, our Sentry Integrity Monitoring Sonar (IMS) is the only commercially available wide-area subsea leak detection system. A single Sentry head can provide 360-degree coverage of a 1,200 m diameter area, or more than one billion cubic feet of seawater, automatically alerting the operator as soon as an oil or gas leak is detected.

Detection rates are very impressive, with Sentry being able to detect monophase gas down to 0.1 litre per minute (equivalent to around 1 barrel of oil per day) or monophase oil to 1 litre per minute (equivalent to 9 barrels of oil per day). That means operators can react quickly to an infrastructure integrity breach before it becomes a bigger environmental and financial problem.

Sentry is an active acoustic-based solution that is based on a remotely operated vehicle (ROV) deployable low-power sonar proven for long-term monitoring. It’s available as a wired solution, that can be connected via existing subsea infrastructure directly into a surface asset. There, a Sentry workstation with graphical user interface (GUI) is able to provide users with clear real-time and automatic alerts of any oil or gas leaks.

It’s also available as a wireless, battery-powered solution for semi-permanent deployment, with data transmitted acoustically to a topside transceiver system. The transceiver can be deployed from a platform, buoy, vessel of opportunity or, now more commonly, via uncrewed surface vehicles (USVs).

The challenge

The worldwide quantity of flowlines, spool pieces, pipeline end termination units, risers and all manner of other installed subsea assets is staggering. All serve as important interconnecting elements in the overall offshore hydrocarbon supply chain. With an aging asset portfolio, it is sometimes very difficult to understand how these assets have been moving during their operational life and what this means to their accumulated fatigue figures and, therefore, safe end-of-life point.

At one offshore field development, Oceaneering, was set a challenge by an international operator. They suspected spool piece movement caused by slugging events, and asked Oceaneering Inc. to provide subsea data for third party analysis so the extent and frequency of movement could be determined. They hoped this would help with the introduction of mitigation measures that would ensure safe and controlled production from the connected producing wells.

With the field located in over 1,000 m of water and with no designed-in points for sensor mounting or hardwired connectivity, this was easier said than done.

The solution

Oceaneering turned to our wirelessly communicating and intelligent monitoring sensors called Subsea Monitoring, Analysis and Report Technology, or SMART for short. Additionally, a series of Autonomous Monitoring Transponders, or AMTs, were deployed within a seabed array to detect any longer period movement that SMARTs would be unable to detect.

Battery operated SMARTs were chosen as they incorporate a low-power inertial measurement unit, or IMU, that can precisely measure the installed sensor’s six degrees of freedom. This means that 3-axes of rotation and 3-axes of acceleration relating to the SMART sensor’s movement can be measured at very high sampling rates over a measurement window set by the operator.

This measurement window, which can be adjusted acoustically at any time from a topside transceiver, can be set between a minimum period of approximately 5 minutes to continuous recording. However, a one-hour measurement window is far more commonplace.

Once the measurement window has ended, SMARTs analyse the recorded raw data, producing and storing one statistical summary file for each window period. When required, these summary files can be requested for wireless transmission through the water column from each SMART’s location to a topside transceiver using Sonardyne’s fast and robust 6G Wideband 2 acoustic protocol on the Dunker 6 LBL and telemetry transceiver.

Importantly for the operator, all SMART raw, time-series, data is securely recorded and saved in-situ for more detailed analysis post-recovery.

Through the combination of edge analytics, low power electronics and acoustic communications, SMARTs could be installed for over a year. Even longer deployments are achievable by supplying larger battery packs or reducing the sampling frequency.

SMARTs are designed for high frequency motion monitoring, but the operator was equally concerned that longer periods of motion were in play that may have caused the subsea asset to gradually move from its installed position. Thus, monitoring for possible flow induced vibration (FIV) and vortex induced vibration (VIV) was also required. To monitor this motion, Oceaneering Inc. chose another Sonardyne sensor called an AMT.

AMTs are used for long-term survey and monitoring applications where instruments are needed to acquire acoustic ranges and other sensor data, like pressure, temperature, and sound velocities, without any surface control. By creating a Long Base Line (LBL) array of static seabed located AMTs with an AMT on the asset needing to be monitored, highly accurate measurements of any horizontal movement of the monitored asset can be measured, accurately timestamped, and logged. Vertical movement of the asset-mounted AMT can also be determined by the recording of precise pressure sensor information and comparing it to those from the control array.

An additional benefit identified by Oceaneering is that data from the AMTs can be wirelessly recovered using the same topside hardware as that of the SMART, resulting in less topside subsystems.

The results

Oceaneering mobilised the equipment in 2018 and it has been in operation ever since. The performance of the SMARTs in determining motion characteristics, coupled with the motion mitigation measures that were introduced, enabled the operator to continue producing safely and within the design life of the installed spool pieces. What’s more, the operator now has a far better understanding of their accumulated fatigue figures for the spool pieces and is able to determine the safe end-of-life point for their subsea assets.

The solution

The catastrophic 2004 Indian Ocean Tsunami led Sonardyne’s founder, John Partridge, to initiate development of a variant of the Compatt 5 seabed transponder to detect a Tsunami passing overhead.

With an extensive track record in the oil and gas industry, this instrument was ideal to form the heart of a TDS requiring very high reliability. Nevertheless, integration of a Digiquartz pressure sensor to enable the Compatt 5 as a BPR, required significant development. This particularly involved reduction of the power required for continuous operation on battery power. Similarly, a new transceiver with low quiescent power, capable of long endurance deployment on a surface telemetry buoy, also had to be developed.

Development was so rapid that when India’s National Institute of Ocean Technology (NIOT) in Chennai, started looking for a TDS in 2005, it was ready for competitive field trial. Sonardyne’s solution was subsequently selected in 2006, leading to deployment of operational systems in the Bay of Bengal and Arabian Sea in 2007.

In normal operation the Digiquartz pressure sensor in the BPR continuously measures water pressure and this data is stored every 15 seconds. The pressure data is then acoustically transmitted every hour to the surface, where an acoustically baffled transceiver, mounted beneath a buoy, receives this data. The buoy is linked to NIOT’s Mission Control Centre (MCC) by satellite communications, so that not only can data be transmitted ashore quickly, but also the health of the BPR is remotely monitored and, if necessary, reconfigured.

Embedded in the BPR is the National Oceanic and Atmospheric Administration’s (NOAA) Tsunami detection algorithm, which compares each measurement to the predicted pressure [Figure]. This predicted pressure uses the previous 3-hour history to take account of tide, weather and temperature variation. Should the difference between the two exceed a programmable default threshold of 3 cm for two consecutive samples, the BPR switches into Tsunami Alert Mode, which then initiates a sequence of data transmissions for the next few hours.

Sonardyne’s Wideband acoustics are central to the functioning of the system, and with the subsequent replacement of the Compatt 5 with Compatt 6, Sonardyne’s latest TDS offering is equipped with the most robust and efficient wideband acoustic telemetry available.

The results

Soon after the first batch of BPRs were deployed, on the 12^th September 2007, the system detected its first Tsunami, which was triggered by an 8.2 magnitude event off the coast of Sumatra at 04° 30’ S 101° 18’ E. How the Tsunami generated was tracked across three of the Indian Tsunami Buoys (ITB) is shown in the gallery.

Located between 1,760 – 2,300 km away, all three stations recorded the seismic ground wave arrival between 7 – 12 mins after the event started. Between 2 – 3 hrs later, the wave itself, which was less than 10 cm in height, passed over the three BPRs, indicating that it had travelled at between 740 – 800 km/h over this period.

Today, Sonardyne’s TDS continues to deliver bottom pressure and event data to NIOT, which is responsible for delivering sea-level data to the Indian Tsunami Early Warning Center (ITEWC) at the Indian National Centre for Ocean Information Sciences (INCOIS) in Hyderabad. In 2014, NIOT reported that system data availability had been 98.83%, with a Mean Time Between Failure (MTBF) of 1.62 years, noting that the majority of these failures were due to external impacts, including weather and human interference with the surface buoys, resulting in damage to surface communication and data systems.

The challenge

Sometimes, it’s not always possible to account for all of the variables that an oilfield infrastructure is subject to. This can lead to issues. External vortex induced vibration (VIV) or internal flow induced vibration (FIV), which can sometimes be caused by slugging. Slugging is created by variable or irregular flow of gas and fluids through risers, pipelines, flowlines or spool pieces.

These issues can cause problems for process equipment, impact production efficiency and, critically, accelerate pipeline fatigue. This has knock-on effects for design life. It can even cause pipelines to be displaced, entrenched or erode the supports they stand on.

When FIV occurs, pipeline engineers need all the information they can get about just how much this is happening and to what degree. This enables them to re-calculate the remaining fatigue life of the infrastructure and decide on the best remediation methods. Unfortunately, monitoring exactly what is happening – what forces the pipelines, flowlines or spool pieces are being subjected to – can be challenging, especially in deep water.

International subsea engineering company Oceaneering International Inc. was asked by an operator to solve this exact problem. They had a number of spool pieces deployed in more than 1,000 metres of water, running between riser bases and flowline termination assemblies. They were being subjected to sudden and frequent slugging movements.

These movements had already resulted in new spool piece supports having to be installed. The operator’s engineers needed to assess the resilience of the new supports and learn more about the vibration the spool pieces were encountering. The challenge was that no motion monitoring sensors had been fitted prior to commissioning. The solution would need to provide accurate and accessible data using a technique that was not cost-prohibitive to install and operate.

The solution

Oceaneering’s solution used an innovative, wireless approach with Sonardyne’s Subsea Monitoring, Analysis, and Reporting Technology (SMART) sensor as a key element of the project.

SMART sensors are, well, smart. They contain low-power MEMs-based (micro-electric mechanical systems) inertial measurement units (IMUs), subsea processing power and integrated acoustic modem capabilities. This means they can autonomously measure, log and process high-frequency, pipeline or spool piece acceleration and angular rate motion over pre-programmed monitoring intervals.

Importantly, SMARTs, which can be integrated with many different subsea sensors to suit a wide variety of applications, process data at source. This is then sent as small statistical summary packets of data – based on parameters set by the user – through the water column to a surface transceiver. This method reduces the need to send time-series, or raw, data up to the surface for analysis, which prolongs battery life, maximizes bandwidth availability and provides useful information to engineers faster. It’s edge analytics and subsea communication technology in one battery-powered autonomous compact unit. And it’s able to work on extended deployments down to 7,000 metres water depth.

For the high-frequency motion, SMARTS were installed on each spool piece at a location between the riser and flowline termination assemblies. To monitor lower frequency movement on one of the spool pieces, another Sonardyne technology was used: Autonomous Monitoring Transponders(AMTs).

AMTs are most commonly used for long-term survey and monitoring tasks where instruments are needed for acquiring acoustic ranges and sensor data without surface control. They time-stamp data and log it internally, to be retrieved when it’s needed at the surface.

By creating a Long BaseLine (LBL) array of “static” AMTs, to which “mobile” AMTs installed on a spool piece and fitted with sound velocity sensors can range, highly precise measurements of any horizontal movement of that spool piece can be monitored and logged. By fitting the mobile AMTs with Digiquartz pressure transducers, vertical motion could also be tracked accurately within the array.

Before installing the SMARTs and AMTs, Oceaneering surveyed the seabed location. This was done to determine the LBL array design and SMART and mobile AMT positioning. Oceaneering designed and built ROV-installable spool monitoring clamps. This allowed the SMARTs and AMTs to be easily attached to the spool pieces. For the LBL array, four AMTs were placed in tripod stands at predefined locations for optimal ranging.

Following installation, confirmation that all the SMARTs and AMTs were working and a post-installation survey, the autonomous and intelligent instruments were then just left to do their work. A huge benefit of both instruments’ design is that they can be left unattended for three years thanks to their internally monitored lithium primary cells.

Anyone with these instruments deployed in their field has a choice in how to collect the data generated. If it’s close to a topside facility, they can deploy a Sonardyne Dunker 6 transceiver permanently, via a deployment pole for the duration of the monitoring, or temporarily over-the-side, via a winch or A-frame.

If the subsea infrastructure is more remote, they could periodically send a support vessel or an unmanned autonomous surface vessel with a Dunker 6 to harvest the data. For this project, while the site was deep, it was close enough to the customer’s production facility. Oceaneering chose temporary deployments, using the Dunker 6 from an onboard crane, as and when data collection was required.

The results

Since commissioning in the summer of 2018, continuous SMART monitoring of the spools, at four-minute intervals has taken place. Packets of data from both SMART and AMT devices, including raw runtime data, have routinely been sent to the surface. Once received, it has been analysed and used in predictive modelling. This has enabled the operator to calculate the accumulated fatigue and remaining operational design life of their assets.

Gaining access to the spools’ motion characteristics has been invaluable to the operator. It’s data they would have been expensive to access through other means. It has led to a deeper understanding of each spool’s motion frequency, rotation angles and cycle times. Where previously the operator had concerns about the remaining operational life of the spools, they now know the operational life is within the limits of the productive life of the field.

This is a great result for the operator, but also for Oceaneering and Sonardyne. By working together we were able to find a cost-effective and viable solution for the operator and future customers with similar challenges. By combining our expertise and flexible instruments as an integrated solution, the supply chain is able to tackle operators’ deepest challenges, quite literally.

Life-of-field monitoring

To maintain the integrity of the FSHRs, the Subsea Technology Group from Petrobras’s R&D Centre in Brazil, prepared a specification for PAI of a comprehensive life-of-field subsea monitoring system and contracted BMT Scientific Marine Services as the systems integrator responsible for its delivery.  

BMT has experience in the development of offshore monitoring systems and, following the successful development of a similar system for the Petrobras P·52 platform in Brazil in 2007, BMT again chose to partner with Sonardyne for the positioning and telemetry component of the riser monitoring system. 

The primary requirement for the acoustic instrumentation is to monitor the position of each riser tower and of the turret buoy relative to the seabed. In addition, integrated sensors monitor depth, temperature, inclination and sound speed whilst the integrated modem transfers data from the load and attitude monitoring system on each riser tower to the turret buoy. The system uses Sonardyne Wideband acoustic telemetry to guarantee high speed and reliable data communications for all these tasks. 

Integrity – Measure, command and monitor

To ensure line-of-sight to each riser tower without obstruction by the flexible risers or mooring lines, the turret buoy was equipped with three of our transceivers. The transceivers perform the following multiple functions: 

• Measure ranges directly from themselves to the seabed transponder array in order to provide an accurate position for the turret buoy. 

• Send commands to transponders mounted near the top of each riser tower, instructing them to measure the ranges to the seabed array. The positions of the risers can then be accurately determined.  

• Acquire sensor data from the riser transponders and the seabed array. 

• Send commands to, and recover data from, BMT’s data logger on the risers, fitted with an acoustic modem.

The transponder on the risers and on the seabed are versions of our Autonomous Monitoring Transponders (AMTs) which operate an efficient Wideband command protocol. 

This allows much faster set up of transponder parameters and enables the sensors fitted to the riser transponders to be measured and reported at the same time as the acoustic measurements are made, greatly speeding up the acoustic monitoring cycle. 

In normal operation, data acquisition will be controlled by the topside monitoring system on the FPSO. In the event of a disconnection due to adverse weather or maintenance, the subsea system continues to record data on the turret buoy, which can later be downloaded by the FPSO or another vessel for processing by Petrobras proprietary software.  

The integrity monitoring system provides valuable data about the movement from either vortex-induced vibration or flow-induced vibration and loading on hybrid riser systems from currents and extreme weather events. 

The system demonstrated a growing demand for reliable subsea remote integrity monitoring that has been enabled by the high performance of Sonardyne monitoring and acoustic positioning, data communication systems and subsea strain and motion sensing systems.  

P-52 permanent subsea riser monitoring system

Sonardyne previously supplied the acoustic positioning and data recovery equipment for the single FSHR close to the Petrobras P-52 platform in the Brazilian Roncador field.  

Installed in the Autumn of 2007, a single acoustic transceiver on the platform communicates with the transponders and modem on the risers and with a seabed array of five Sonardyne Compatt 5 transponders.

Because of the large amount of data to recover from the data logger on the risers – over 90 Mbytes in the first six months – our High Data Rate Link (HDRL) was employed to transfer data from the loqqer to the platform. The monitoring system sends strain, motion and position information every four hours. 

This transfers data at the speed of 15,000 bps and is ideal for transferring the large data records to the surface error free and as efficiently as possible.  

Since its commissioning in 2007, the system has provided invaluable data for analysing the movement of the riser tower, allowing confidence in the development of more complex FSHR installations such as in the Cascade and Chinook field. 

(The original version of this article was first published in Sonardyne’s Baseline magazine in 2009. It has been lightly edited for present tense).  

https://www.sonardyne.com/wp-content/uploads/2021/06/baseline_issue_4.pdf  

The challenge

While satellite observations have previously shown that the flank of the volcano is slowly sliding towards the sea, until the establishment of this network, it had been impossible to confirm if and how the submerged segment was moving beneath the ocean.

Results published in the international journal Science Advances confirm that the entire flank of the volcano is in gravity-driven motion and in one event the slope slipped about four centimetres in just eight days. The risk is that sudden and rapid failure of the entire slope could result in a catastrophic tsunami in the Mediterranean.

The solution

A network of five Sonardyne Autonomous Monitoring Transponders (AMTs) were deployed in April 2016 by scientists at GEOMAR and Kiel University. The placement of the transponders covered the fault line that represents the boundary between the sliding flank and the stable slope. Three AMTs were situated on the sliding sector and the final two on the side of the fault line that was presumed to be stable.

The AMTs acoustically measure the distances between each other with a millimetric precision. This sound based underwater geodetic monitoring network, so-called marine geodesy, was a first for monitoring a volcano’s movement underwater.

Geraint West, Global Business Manager – Ocean Science told us “The AMT is a highly flexible instrument that has been used by research institutes around the world to measure seabed movements as diverse as rapid canyon turbidity flows to plate motion at deep subduction zones. This project is the first time that it has been used to measure the slippage of a volcano’s submerged flank.”

“The AMT was originally developed to measure deformation of the seabed caused by the extraction of hydrocarbons over several years.” Tom Bennetts, Sonardyne Projects Manager added.

“Sonardyne first deployed AMTs on a large project over the Ormen Lange field in the Norwegian sector of the North Sea. For that project, some 220 individual instruments were deployed. The precision and endurance required for the Ormen Lange project showed us – and others – that our AMTs are also ideally suited for scientific studies of the seabed.” Bennetts clarified.

The results

The results published in the international journal Science Advances confirm that the entire flank of the volcano is in gravity-driven motion rather than the ascent of magma. One event saw the slope slip about four centimetres in just eight days. There is a very real risk that a sudden and rapid failure of the entire slope could result in a catastrophic tsunami in the Mediterranean.

Chris Hammersley, Project Engineer – Navigation Systems for Sonardyne said “Through several projects with major AMT deployments, we’ve built up a close relationship with the scientists and engineers at GEOMAR. We’re on standby to support them remotely through AMT deployment and routine data recovery missions. From our head office in the UK, we’re able to support these projects remotely, 24/7. For the Mount Etna Measurement project, we’ve been able to advise on optimal configurations for the instruments as well as troubleshoot any issues that arise, ensuring that GEOMAR have been able to use valuable ship time on site to best effect.”

The results of the study do not allow a prediction of whether and when a rapid failure of the slope might occur. For this reason, further research into the geological processes at and around Etna and other coastal volcanoes will continue. The success of our AMT deployments at Etna has secured the future use of sound-based geodetic monitoring networks for further studies.

Read more about GEOMAR’s project here.

The challenge

The transition zone environment is often highly reverberant, the vessels used are often noisy and they can be a considerable distance from the acoustic transponders used to position the nodes. What’s more, shallow water makes nodes especially prone to movement, adding a further complication to proceedings.

Repeated node positioning operations conducted from vessels are costly and time consuming. Noisy environments can inhibit the quality of information and manned vessels are a costly option for completing work that can be done remotely.

The solution

To solve these issues, Sonardyne has created our TZ Transceiver. It’s very compact and simple to operate. Ideally suited to installation on manned workboats and USVs, it’s already being used for conducting acoustic positioning operations with seismic nodes deployed in the transition zone.

The TZ Transceiver works by collecting hundreds of acoustic ranges from transponders such as our TZ/OBC, TZ Transponder and Small Seismic Transponder 6. These are often attached either directly to the seismic node or to a deployment rope nearby. The ranges are merged with the vessel or USV’s GNSS data so that an accurate position of each node can be calculated.

Mounting our TZ Transceiver onto a USV is ideal because it can follow the mother vessel autonomously and position the nodes as they are being deployed. Alternatively, it can be tasked to perform a position verification check to ensure the nodes have not moved.

The results

Fitting a TZ Transceiver to a USV such as the installation on Maritime Robotics’  Mariner USV is a very cost-effective force multiplier. The addition of the transceiver eliminates the need for a manned vessel to conduct the same routine operations.

Weighing in at 1,900 kg, Mariner is 6 m-long, 2 m-wide. It includes a moon-pool and an elevator mechanism for sinking and lowering sensors, such as our TZ Transceiver.

The vehicle is designed for both offshore and coastal applications and can be deployed and operated from a larger manned vessel or even over the horizon from a shoreside office. This increases the productivity of the existing survey crew as well as the overall profitability of seismic operations.