CCS is considered one of the most promising technologies for significantly reducing the amount of global CO₂ emissions by 2030. One important aspect of fine tuning the technology is to ensure that stored CO₂ does not escape from geologic repositories, or wells, into which it is pumped. Research activities and several ongoing CO₂ injection-projects worldwide are proving that CO₂ that is injected into underground deposits is highly unlikely to leak out into the atmosphere.

To ensure safe storage, it is important to develop standards for CO₂ sequestration. The biggest risk associated with CO₂ storage is leakage through wells, and uniform methods and standards for design, building, operation and monitoring of CO₂ injection wells must be established. These standards are often referred to as well integrity.

Last year the Norwegian Petroleum Safety Authority (PSA) ordered a study on well integrity from the Norwegian research institute SINTEF. The report was delivered in December last year, and reviews current practices and experience from industrial analogues.

“This new report is a very important tool in ongoing work on establishing methods and standards to ensure safe CO₂ storage,” says Bellona energy adviser Dr. Aage Stangeland.

Some reporters have questioned if this report identifies a new and earlier unknown risk related to CCS. According to technical experts this is certainly not the case. Stangeland puts it this way:

“The report does not add anything new to the CCS debate, but it is a very good summary of already well-known aspects of CO₂ storage. The report addresses well integrity, i.e. methods to ensure that there is no leakage of CO₂ from the injection well. It has been known for a long time that we need standards for ensuring well integrity.”

The European Commission established the Technology Platform on Zero Emission Fossil Fuel Power Plants (ZEP) in 2005. More than 200 CCS experts from around Europe participate in ZEP, whose aim is to establish recommendations for how CCS can be commercialised.

ZEP long ago flagged well integrity as an important research and development area. The new report from SINTEF will make it easier to point out specific research actions that are required. With this new report it will be easier to define the challenges related to well integrity, and it will also be easier to establish good solutions.

“As far as I can see, the report does not say anything indicating that CO₂ storage should not be safe. It is only a very good study on well integrity, and, as such, a report we need in our work to ensure safe storage,” said Stangeland.