In our first two blogs, we explored the importance of subsea monitoring for offshore carbon capture and storage (CCS) projects and the key parameters that need to be measured. In this, our final blog, we’ll delve into how our innovative technology is transforming the landscape of CCS monitoring, making it more efficient, cost-effective and environmentally friendly. We are also pleased to introduce our latest animation summarising this blog series – more of that later…

The goal: A reliable subsea monitoring system

When it comes to subsea CCS monitoring, what are we really trying to achieve? Our solution is best thought of as a sophisticated underwater monitoring and early warning system, not an in-situ forensic analysis lab. Our aim, therefore, is to create a system that reliably alerts operators to events while maintaining a very low rate of false alarms. We’re not aiming to conduct an in-depth scientific study of water quality; instead, we’re providing actionable data that enables swift decision making in the very unlikely event of CO2 containment loss.

The challenge: Accessing subsea data

One of the most critical aspects of effective CCS monitoring is timely access to accurate data. This allows for better and faster decision making, potentially preventing large-scale discharge events. However, accessing this data subsea is not a simple task. As described in our previous blog, the monitoring devices are either located on the seabed or on subsea infrastructure, often without any direct connection to surface platforms or onshore facilities.

For our chemical and passive sonar landers, accessing data while they remain deployed on the seabed is crucial. This allows for:

• Quality checks of the lander’s sensors during commissioning and prior to departing site
• Early detection of changes in water property parameters once data has been harvested
• Ability to adjust settings or sample rates remotely
• Monitoring of remaining battery life

The solution: Sonardyne’s in-depth experience with delivering integrated subsea systems

Given the above challenge, this is where our over half a century’s expertise in integrating subsea wireless acoustic communications with numerous sensors and sub-systems comes into play. Our experience and technology allow for robust data transfer over large distances, from subsea monitoring points to remote vehicles, buoys or vessels on the sea’s surface.

This in-situ access is enabled by a dedicated Sonardyne acoustic Modem 6 wireless communications device integrated into the subsea lander. The Modem 6 is connected to the central processing hub (CPH), which really is the beating heart of the system. The CPH securely records all data from each of the sensors and distributes power around the lander’s monitoring devices from the battery modules. Crucially, the CPH performs Edge processing, compressing the data to allow efficient acoustic data transmission via the subsea modem.

Additionally, and although CCS is now at the forefront of the current climate change agenda, we have been investigating the technologies used in offshore carbon capture and storage monitoring for over a decade. In 2014 we, along with several industry partners, demonstrated the concept of a measurement monitoring and verification (MMV) system-of-systems employing wireless data gathering during a three-year Energy Technologies Institute (ETI) funded project. This project successfully showed that chemical and physical sensors could be used to actively monitor key locations with their data being accessed in-situ using wireless acoustic communications, which was ultimately transmitted to shore via satellite for analysis and interpretation. Further information from this project can be found via the links below.

https://issuu.com/sonardyneinternationalltd/docs/baseline_issue_12 – page 20

https://issuu.com/sonardyneinternationalltd/docs/baseline_issue_18 – page 14

A chemical lander with passive sonar on top

Uncrewed surface vehicles: The new data harvesters

Traditionally, crewed vessels were used to collect data from subsea monitoring devices. However, with the push towards reducing emissions and minimising human presence in hazardous offshore environments, uncrewed surface vehicles (USVs) are fast becoming the go-to solution.

With our technology as payload, USVs excel as an interface, or gateway, point between subsea monitoring devices (whether for wellhead, subsidence or water property monitoring) and satellite communications linked to cloud-based portals and finally, onshore control centres.

Case study: Shell’s use of carbon-neutral vehicles

In a data harvesting project for Norske Shell, we employed XOCEAN’s XO-450 USV to remotely access subsidence monitoring data from an array of our Fetch AZA nodes. This operation, conducted about 120 km offshore Norway, proved to be a game-changer:

• Data was transmitted in near real-time to Shell’s reservoir engineers during the USV mission.
• The entire operation consumed only 105 litres of fuel, compared to the 5.5 tons per day used by previous vessel-based operations.
• The harvest has been successfully repeated every year since 2020.

Read the full case study here.

XOCEAN’s XO-450 USV was used to remotely harvest data 120km offshore Norway.

Cost-effective and efficient monitoring

Our approach to CCS monitoring offers several cost-saving benefits:

• Reduced recovery costs: Two-way communication with subsea devices through USVs or buoys eliminates the need for frequent physical recovery of our monitoring solutions
• Flexible deployment: Our monitoring equipment is designed to be deployed from smaller vessels of opportunity, reducing operational deployment and recovery costs
• Continuous data logging: We can offer a dual redundant solution for chemical landers, ensuring uninterrupted data collection – because the most expensive data is that which hasn’t been recorded
• Edge processing: Our chemical lander’s CPH performs in-situ Edge processing, allowing efficient data transmission via acoustic communications. All raw data remains securely stored on the CPH for later physical recovery for further analysis, interpretation and reporting

Cloud-based data management

Our solution includes a cloud-based processing and access point, allowing authorised stakeholders to securely access data on-demand from anywhere in the world. This eliminates the need for site visits or reliance on subcontractor reports.

Cloud platform features include:

• Data processing algorithms: customisable for your individual requirements on each site
• Data visualisation: to provide critical decision making information
• Historical data analysis tools: identify patterns and trends and use these to inform future projects
• Customisable alerts and notifications: select the notification frequency best suited to the location and size of the area being monitored
• Scalable architecture to handle large volumes of data: different size storage sites will require differing amounts of data. Scale your operations to suit the size of your site

Subsea and above ground communications are vital for successful CCS.

Conclusion

Our integrated approach to CCS monitoring combines cutting-edge acoustic communication technology, subsea Edge processing from a variety of integrated sensors, uncrewed surface vehicles, large area monitoring surveys using remotely operated towed vehicles (ROTVs), high resolution side scan sonar imagery with automated target recognition algorithms, and cloud-based data management. This comprehensive solution forms an environmentally friendly ecosystem that offers advanced monitoring capabilities, cost-effective operations, and reliable data collection – all crucial elements for the success of offshore carbon capture and storage projects.

To accompany and summarise this blog series, we’ve produced a short animation. We’re excited to give you first sight of it here. 

If you’d like to learn more about how Sonardyne can meet your subsea CCS monitoring needs, we invite you to get in touch with our team of experts. We can provide detailed specifications, customised solutions, and expert advice to ensure your offshore CCS project benefits from the most advanced monitoring technology available.

Stephen Auld.

Missed them first time around? Here are the previous blogs in this series:

Blog 1 – Carbon capture and storage a critical component of climate change mitigation

Blog 2 – The critical role of monitoring in subsea carbon capture and storage