Natural Well Sealing

Sealing wells with clay: sustainable and economical sealing of wells

The RCSG is leading the way with large-scale experimental research into subsurface technology necessary for sustainable underground energy applications. The RCSG shortens the lead time from development on a laboratory scale to application in the field. In doing so, it explicitly seeks cooperation with parties from this market. The Natural Well Sealing project is an example of such a successful collaboration. TNO, together with 7 partners, started a project in 2015 to investigate the feasibility of using clay and salt to seal wells. 

With the RCSG’s testing facilities, tests could be done with the right size and under the pressure and temperature prevailing at more than 2 km depth. These tests are necessary to conduct a pilot in the field in a production well. At the RCSG, the experiments are conceived and conducted. The RCSG thus contributes to sustainable innovation.

Can a sustainable seal be made with bentonite? 

The Natural Sealing van Putten project is investigating the material bentonite, among others. Bentonite is a natural type of clay whose particles are so small that they can make the soil leakproof. The extent to which bentonite is suitable for making the process of plug and abandonment (P&A) of wells more sustainable has been examined. Bentonite has ‘self-healing’ properties in the borehole. Thus, bentonite can remain leak-proof over a long period of time (millions of years). The material is naturally present in the subsurface, which means that a restoration of the initial situation is closely approached. The costs of using bentonite are also expected to be lower due to simple installation equipment and lower material costs. Applying bentonite here would therefore be an important innovation. 

Key role test site RCSG 

A well plug is placed at great depth (2 – 3 km). At this depth in the subsurface, the pressure and temperature are high. This can have a major impact on the properties of any material. A challenge is that a plug at that great depth is no longer accessible after placement. So it is important that the material is tested and qualified under real conditions before it is placed in a ‘real’ well. This is where the RCSG plays a key role. It is equipped with large-scale testing equipment and a research well, including a drilling rig. This unique test site is where the crucial temperature and pressure tests are done at depth. 

Key role test site RCSG 

A well plug is placed at great depth (2 – 3 km). At this depth in the subsurface, the pressure and temperature are high. This can have a major impact on the properties of any material. A challenge is that a plug at that great depth is no longer accessible after placement. So it is important that the material is tested and qualified under real conditions before it is placed in a ‘real’ well. This is where the RCSG plays a key role. It is equipped with large-scale testing equipment and a research well, including a drilling rig. This unique test site is where the crucial temperature and pressure tests are done at depth. 

Knowledge partner for companies and institutions 

The RCSG is the partner for experimental research into technology for sustainable underground energy applications. The full-scale research facilities at the Rijswijk site enable a wide range of studies to be carried out. It is the ideal learning environment for (energy) companies, knowledge institutions and SMEs. The RCSG is taking major steps towards a sustainable future in the Netherlands, but also worldwide.

Contact us

Want to know more about this project, have a question, or would like to visit the RCSG? Then contact us via the contact form.