Correlation analysis for online CO₂ leakage monitoring in geological sequestration

The paper presents a method for monitoring CO₂ leakage in geological carbon dioxide sequestration. The unsteady state dispersion of leakage CO₂ from geosequestration simulation results showed that the ensemble trend of elevated concentration caused by CO₂ leakage can be viewed as a concentration step change perturbation to the background variation and the initial stage of dispersion process is an increasing variation. The correlation between O₂ and CO₂ variation is well linear if there is no leakage. The external linear perturbation decreases the correlation coefficient. Moreover, too large step change concentration will also reduce the average correlation coefficient. Therefore, online correlation analysis between O₂ and CO₂ in atmosphere is useful to distinguish the leakage CO₂ from complex background variation especially at the beginning of leakage occurring.