Research spotlight: Exploring CCS solutions in Scotland

Researchers from the Lyell Centre for Earth and Marine Sciences are leading a study exploring the relationship between long-term carbon dioxide storage and legacy oil and gas wells in Scotland’s North Sea. Sponsored by Crown Estate Scotland, the project is examining the position of such wells and evaluating their possible impact on Carbon Capture and Storage (CCS), a technical and complex process that requires a suite of technologies to capture CO2 from industrial sources and transport it to storage facilities underground.

To achieve the UK’s net-zero targets, the UK Government is targeting the capture and storage of 20-30 million tons of carbon dioxide per year by 2030, increasing the importance of CCS technology.

Through CCS, it is estimated that the Scottish North Sea could provide enough storage to prevent up to 53 thousand million tonnes of CO2 being released into the atmosphere. However, full-scale deployment of CCS by licensed operators in the North Sea can only proceed once the implications of historic oil and gas wellbores (termed legacy wells) within and near the underground storage sites are fully understood.

The EPSRC (Engineering and Physical Sciences Research Council)-supported project, ‘Towards Evaluating and Managing Risks Associated with Legacy Wells and Offshore Gas Storage in Scotland’, is led by Lyell Centre PhD candidate Benjamin Pullen and Assistant Professor Dr Aaron Cahill.

Through collaboration with 54 operators, regulators, and prospective leaseholders, Ben gathered and analysed data from 12,264 the North Sea legacy wells and developed a multi-criteria decision analysis (MDCA) model to understand how they might influence the containment of stored carbon dioxide.

This innovative model, which underpinned the 'consideration score' created to identify and categorise the risk profile of individual wells, helps to streamline risk assessments and prioritises wells for detailed evaluation, depending on whether they're deemed lower or higher risk, offering an efficient, scalable solution that enhances the safety and reliability of CCS projects.

The research complements traditional site-specific assessments, providing a robust framework for regulators, operators and investors to manage legacy well risks effectively.

The knowledge gleaned will also help Crown Estate Scotland in its role as manager of property rights for offshore gas storage and to inform decision-making on the deployment of CCS, working alongside key stakeholders.

A paper outlining the findings, entitled Differentiating legacy wellbores in the Scottish North Sea using multi-criteria decision analysis with a view to minimising containment risk for carbon capture and storage, was published in the International Journal of Greenhouse Gas Control in March 2025.