CO2 storage relies on the injection of the gas either via pre-existing wellbores or, in the future, new wells. CO2 is potentially corrosive and in certain conditions can induce rapid cooling. Both conditions are detrimental to wellbores so it's important to understand how these conditions occur and what mitigation options are available. The GHGT-13 conference in Lausanne has dedicated a session to the topic. Delegates were briefed on a project by the Norwegian research organisation SINTEF on a laboratory study on the effects of rapid cooling and heating of a section of core that was representative of a cased and cemented wellbore within a rock formation. After subjecting the sample to cyclical temperature fluctuations a computer tomography image was used to detect the presence of fractures. Cement can separate from rock formations forming channels if temperature conditions are not controlled. This experimental work has also shown that the timing between injection and pauses can influence thermal stress. Initial conclusions suggest that long operational pauses should be avoided. Heating CO2 prior to injection could also be used to reduce the effects of high temperature contrasts.
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