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Case study

A ‘custom-off-the-shelf’ product provides a timely solution for Dana Petroleum.

Dana Petroleum

September 27, 2023

Our experience and expertise allowed us to rapidly adapt our off-the-shelf technology for Dana Petroleum. This delivered a cost-efficient, low environmental impact, and timely solution for them to monitor their suspended wells in the North Sea.

The challenge.

As they reach the end of their productive life, oil and gas well heads still need to be monitored whilst suspended – for up to five years, before they become fully abandoned / decommissioned. A regime must be in place to monitor the assets ‘in perpetuity’ to meet government regulations. As this is ‘abandonment expenditure’, rather than capital expenditure, any monitoring schedule must be conducted as cost effectively as possible.

Dana Petroleum (Netherlands) was faced with one such challenge in early 2023 when they needed to plan and implement a well annulus monitoring schedule for suspended wells at their Van Ghent and Van Nes subsea wells, situated in the North Sea approximately 60km West of The Hague. The wells were situated alongside others still in operation and although the topside platform remained, communication links with the sensors on the suspended subsea wells had been lost. There was an additional challenge of the system needing to be in place within 12 weeks.

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The solution.

The ’simple’ solution would have been to lay new communication cables from the suspended well heads to the topside platform to enable the monitoring. But this would have been lengthy, expensive and carbon intensive, involving bringing in large vessels to lay long stretches of subsea cables. A quicker, cost effective and lower carbon solution was needed. Having heard about Sonardyne’s experience and expertise in long-term subsea asset monitoring, Dana Petroleum approached us for a solution.

We have many years’ experience in providing subsea pressure and temperature data directly from well downhole gauges, mostly during the appraisal phase in a field development, providing essential data to the reservoir engineers before connection is made to the offshore or onshore facility.

Although Dana Petroleum’s requirement was well within our capabilities, there were some initial unknowns such as; field layout, pressure gauge model and manufacturer and how the equipment would be mounted to the subsea manifold. Also, which topside would be most suitable for data harvest? Something which is typically dictated by the vessel size, noise profile and water depth. The timeframe was also very challenging.

In the following weeks, Dana Petroleum provided information on the field layout, drawings of the subsea infrastructure and a strong specification for a system capable of monitoring the annulus pressures at both locations. Having received this, we were able to provide illustrations of previously designed bracketry, 3D CAD images of our potential offering and expert advice to work out the optimum placement to enable best line of site for data harvesting. With a firm specification and known time constraints we looked to our off-the-shelf products with a view to creating a semi-custom solution with our projects team.

The obvious choice was to make custom alterations to our Autonomous monitoring transponder (AMT). The AMT has been used in a wide variety of different applications including overburden monitoring and pipeline movement monitoring, all utilising and autonomously logging pressure sensor data. These solutions can operate autonomously over long periods of time, over five years – depending on deployment – logging data and making it accessible for wireless upload.

With energy transition currently very high on most Governments agendas, there is a high volume of suspended wells globally that require a form of long-term monitoring. The current high demand for vessels and drive towards a carbon neutral planet means that traditional methods of monitoring are not always going to viable.

However, regardless of the political and economic environment, assets still need monitoring in a safe and responsible way and that’s where Sonardyne comes in. We have a flexible approach to projects where we can provide exactly what the client needs. Whether it’s equipment to monitor a single well or provision of the raw data for a full multi-well campaign, we have the in-house experience.

When I received the initial enquiry from Dana Petroleum, as a previous member of the technical team it was actually quite exciting as I had been looking for an opportunity to drive a low-cost robust solution that fits well within abandonment expenditure budgets.

We have shown all of this is possible to do and provided the system in a very short timeframe.

Colin Sutherland. Sales Manager. Sonardyne

The topside platform of choice was a Nano topside equipped with a ruggedised laptop running Sonardyne’s Monitor software fitted to a small crew transfer vessel that would pass by the wells at regular intervals, delivering workers to the platforms. The size of the vessel dictated a small portable solution but other options are available for all sizes of vessels.

Once the seabed and topside products were selected, custom modifications were made by the projects team to the AMT, allowing the pressure sensor to be connected to the annulus via a flange – rather than inside the AMT –to give flexibility in the location of the AMT and achieve best line of communication with the Nano transceiver when it passed overhead.

A factory acceptance test was witnessed by Dana Petroleum where our projects team provided documentation and coordinated the testing. Following this the equipment was shipped and ready for installation – all within a few months!

The results.

The AMTs were installed by N-Sea using the diving support vessel EDT Protea and acoustic connection was established to test the pressure gauges. Readings came back as expected and the system was set logging. Following several days of logging the vessel returned to each well head to harvest the data and prove the system.

Pressure graph

To fully verify the installation, valve settings were changed at the De Ruyter platform and this was visible in the data. The graph above shows a steady increase in pressure after the valve was opened on 13/07/23. The notable drop in pressure between 14:10 (UTC) and 20:10 (UTC) on 17/07/23 shows when the valve was closed.

Significant cost savings were made by removing the need for new cable infrastructure and utilising a crew transfer vessel for data collection. This also dramatically reduced the carbon footprint of the monitoring schedule.

Subsea issues like communication or power loss are one of the most difficult items to deal with. With existing systems, normally the only option is to do a complete reinstallation, resulting in huge costs and environmental impact. The solution offered by Sonardyne not only bypasses the communication and power loss, but also offered a cost-effective means of reinstating the pressure monitoring, all within a couple of months’ time.

Richard Bus. Senior C/E/I Engineer. Dana-Petroleum

Understanding our customer’s needs and working with our projects team enabled us to provide Dana Petroleum with a customised solution which met with their tight timescale and objectives.

If you have a similar subsea requirement or challenge for us, get in touch to see how we can help.


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