Distinguishing natural seabed methane from leaks at abandoned wells

The North Sea is shifting from a fossil fuel energy system to a green one, and the decision to end oil production by 2050 is accelerating this transition. It brings a large task in closing down oil wells, along with a risk of future leaks. To reduce that risk, the EU has introduced regulation requiring five years of monitoring of abandoned wells.

Abandonment is new to the oil industry, and the technologies needed for the required monitoring are immature. Sensors for continuous monitoring of methane levels in the sea are under development. Once monitoring begins, there will be situations where sensors pick up unexpected changes in methane levels. The methane does not necessarily come from leaking wells, as natural biological processes in the seabed also produce it. However, no available technology can distinguish between naturally formed methane and methane leaking from oil wells.

The CIM - CH4IsotopeMonitor - project will develop and validate a monitoring system and test it offshore. The system can be implemented when unexpected methane levels are measured, and it will be able to determine where the methane originates, so that leaking wells can be closed. Alongside the monitoring equipment, the project will model the biological processes in the seabed, so that the combined solution can give a reliable answer on the origin of the measured methane.

The project is funded by EUDP and runs from 2026 to 2028. Project partners are NxPAS, BlueNord, Nordsøfonden, Fugro and Danish Fluid System Technologies.