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CCS: Storing up lessons

Carbon capture and storage (CCS) is one of the hottest topics on the planet. The PSA wants to learn more about the risks involved and to identify where more information is required.

Two heavyweight technical studies on CCS and associated transport were launched by the PSA in 2008, and the agency is also an observer in an industry project on the same subject. All three of these activities aim to identify risk factors and knowledge gaps involved in dealing with liquefied carbon dioxide under high pressure.

One PSA study, being conducted partly by Det Norske Veritas (DNV), focuses on learning required and risks posed by CCS. Its findings are published on the PSA website. The agency wants more information from its other study on well safety in connection with carbon injection. One question to be answered is whether carbon dioxide could affect existing well barriers designed to prevent hydrocarbon leaks. This and other issues are being assessed by the Sintef research foundation on behalf of the PSA, with conclusions also appear on the agency’s website.

DNV is also carrying out an industry project to study the use of pipelines for large-scale carbon transport in order to identify particular risks related to such operations. The outcome will be a recommended standard for such pipelines, both over land and on the seabed.

“Norway has almost 40 years of experience in processing hydrocarbons and transporting them by pipeline,” says Ole Jacob Næss, the PSA’s discipline leader for structural integrity. “This expertise lays the basis for our involvement with CCS and transport. But carbon dioxide differs from oil and gas in a number of respects.

“That creates a big need among everyone concerned for specific new knowledge and expertise, from design to operation.”
Carbon dioxide is incombustible and heavier than air in gaseous form. A concentration above about 10 per cent can cause suffocation and death.

Efficient transport and storage of this greenhouse in large volumes requires it to be compressed and liquid form.“Separation from exhaust fumes could also leave impurities in the gas,” Mr Næss notes. “The possibility that these might include water creates uncertainty about the risk of corrosion. “We currently lack reliable maximum values for the content of pollutants and water. A lot of research on this issue is under way in Norway and internationally. That’s gratifying, because we need more answers here.”

Plans call for carbon capture at Kårstø north of Stavanger and Mongstad near Bergen for piping offshore and storage in geological structures beneath the North Sea. Among the latter, the prime candidates are the Utsira formation in the Sleipner area and the Johansen formation close to the Troll field.

StatoilHydro has acquired CCS experience on Sleipner East and Snøhvit in the Barents Sea, with virtually pure carbon dioxide being separated from gas production and injected below ground.

“We want to know which factors might influence the risks of large-scale CCS and transport,” says Torleif Husebø, the PSA’s discipline leader for process integrity.

“It’s up to the industry to show that all factors affecting accident risk have been taken into account. Our job is to be a prime mover in defining the knowledge needed and any gaps in it.

“The industry must be prepared in the present phase to show openness and a willingness to share all information of significance for safety.”

By Ole-Johan Faret