At present, oil companies use natural gas for EOR, which allows them to pressure as much oil out of a deposit as they can. But Bellona and others have suggested that using CO₂ for the same purpose would provide some of the geological space necessary to store CO₂ captured from emitting industries and keeping it out of the atmosphere, while making the purchase of captured CO₂ economically viable for carbon producing industries and the oil industry as a transition to carbon free renewables-based energy economy is completed.

Such sequestration, argue adherents of the carbon capture and storage (CSS) process, is essential to making this transition.

There has been debate between Norway and mainland Europe about the cost effectiveness of using EOR. Bellona has come down strongly in a favor of it, and the European Commission has supported the idea as well, despite a Norwegian government commissioned report that said the practice would not be profitable for use in Norwegian oil fields.

Nonetheless, the European Commission last year kicked off a research project to investigate the possibilities of establishing a CCS infrastructure.

The study, called the European Chapter on Combinatorial Optimization  (ECCO) includes 18 partners, and is led by the Norwegian research institute SINTEF – the Norwegian government’s opposing findings notwithstanding – and has a €5.3 million budget.

Bellona is one of the partners in ECCO project, and ultimately believes that CCS deployment is possible in the North Sea by injecting CO₂ into oil wells there.

At a workshop hosted last week at the University of Zagreb – one of the partners in the ECCO project – Croatian oil company INA and its Hungarian counterpart MOL presented their experience with injecting CO₂ for EOR.

EOR experience – success stories from Hungary and Croatia
The main news from the workshop was presented by INA and the MOL who have long experience with injecting CO₂ for EOR.

INA reported positive results on a pilot EOR project that ran from 2001 using 36,000 tonnes CO₂ that was injected into Croatia’s Ivanica oil field – which produced an increase in oil production. The project was so successful that INA has decided to start full-scale use of CO₂ for EOR injection in two of its oil field – the original test site of Ivanica, and Zutica – by 2010. It is expected that 5.4 million tonnes of CO₂ will be injected over a 25 year period, increasing the oil recovery rate by 8 to 10 percent.

Hungary’s MOL oil company reported similar long term experience using CO₂ injection, both of EOR and Enhanced Gas Recovery (EGR). MOL had already started injecting CO₂ to enhance recovery in the mid 1980s.

“The most interesting message is that MOL has proved that CO₂ injection for EGR works,” says Bellona energy advisor, Dr. Aage Stangeland.

“Reservoir engineers working in Western Europe often says EGR doesn’t work, but now they have to rethink their arguments,” he says.

The Norwegian government’s historical resistance
Norway was the site of intense debate through the years 2005 to 2007 over injecting CO₂ into oilfields for EOR purposes. A Bellona Foundation report published in 2005 stated that EOR would be beneficial for all stakeholders, and would accelerate efforts to develop CCS technologies. The report sparked a debate on EOR in government circles. The Norwegian Energy and Oil Ministry commissioned a study of its potential to the government bodies of Gassco, Gassnova and Petoro.

The Gassco-led study said injecting CO₂ for EOR in Norwegian fields, many of which are concentrated in the North Sea, would be unprofitable. Bellona disagreed, saying Gassco and its companion researchers were too conservative in their cost estimates. Bellona asserted, to the contrary, that CO₂ used for EOR could, on average, increase oil production from selected fields in the North Sea by 5 percent. The Norwegian government critcised the Bellona assertion as too optimistic.

But the converse may be true: Bellona’s results may likely be too conservative: SITNEF presented results at the ECCO workshop last week indicating that CO₂ injection could, on average, increase oil production in some North Sea fields by as much as 8 to 10 percent.

EOR in the North Sea is possible
Dr. Stangeland believes that CO₂ injection for EOR in the North Sea could be a possible.
 
“INA and MOL have positive experience with EOR and EGR, and their experience could be shared with companies operating in the North Sea,” he says.

“Such a knowledge sharing combined with upcoming recommendation from the ECCO project will provide new insight that can pave the way for CO₂ for EOR in the North Sea,” Dr. Stangeland says.

“We believe that ECCO will pave way for CO₂ for EOR and EGR in the North Sea. This can accelerate the development of CO₂ capture and storage technology and establish CCS as a new tool in the combat against global warming.”