Geosequestration is an attractive method for removing CO2 from the atmosphere, as explained on our research pages. When CO2 is injected into exhausted petroleum reservoirs, the resulting carbonic acid will react with the cement used to seal abandoned oil wells. To assess the risk of leakage through those wells, Andrew Duguid measured the rate of corrosion of cement under the conditions expected at a depth of about 1 km. To apply his results to longer-term exposure, Bruno Huet has developed a numerical model that captures the reactions of all of the phases of cement exposed to carbonic acid. As shown in the plot above, the model provides excellent quantitative agreement with the experiments. In this case, the plot shows the movement of the boundaries of a white layer of calcium carbonate that precipitates within the cement sample during the reaction.