Leeds: Advances in carbon dioxide storage technology

Research lead

Researchers at Leeds University have shown that porous sandstone under the North Sea from which oil has been extracted could provide a safe reservoir for carbon dioxide. The study found that sandstone reacts with injected fluids more quickly than had been predicted, which is essential if the captured CO2 is not to leak back to the surface.

The work focused on data from the Miller oilfield in the North Sea, where the oil company BP had been pumping seawater into the oil reservoir to enhance the flow of oil. As oil was extracted, the water that was pumped out with it was analysed and this showed that minerals had grown and dissolved as the water travelled through the field.

Significantly, water pumped out with the oil was especially rich in silica, indicating that silicates, usually thought of as very slow to react, had dissolved in the newly-injected seawater over less than a year. This is the type of reaction that would be needed to make carbon dioxide stable in the pore waters, rather like the dissolved carbonate found in still mineral water.

The study gives a clear indication that carbon dioxide sequestered deep underground could also react quickly with rocks to become assimilated into the deep formation water.

The work was supervised by Bruce Yardley, professor in the School of Earth and Environment, who explained: “If CO2 is injected underground we hope that it will react with the water and minerals there in order to be stabilised. That way it spreads into its local environment rather than remaining as a giant gas bubble which might ultimately seep to the surface.”

“It had been thought that reaction might take place over hundreds or thousands of years, but there’s a clear implication in this study that if we inject carbon dioxide into rocks, these reactions will happen quite quickly making it far less likely to escape.”

Although extracting CO2 from power stations and storing it underground has been suggested as a long-term measure for tackling climate change, it has not yet been put to work for this purpose on a large scale.

Earlier this month UK Prime Minister Gordon Brown launched a competition to build one of the world's first carbon capture and storage plants. The Leeds study suggests the technique has long-term potential for safely storing CO2.