Evaluation on of geological suitability for CO₂ storage in salty aquifers in the East China Sea Shelf Basin

Abstracts: Based on the systematic analysis of key geological elements of CO₂ storage in salty aquifers in the East China Sea Shelf Basin, it is believed that under the control of tectonic and sedimentary evolution, the basin shows the characteristics of "Favorable for overall storage, but having differences in the eastern and western depression". The eastern depression is fully rifted, with a large tectonic unit area, thick sediment, and full stratigraphic development; and the potential sequestration systems are the Miocene and Oligocene. The western depression was rifted early, the tectonic unit area is relatively small, with thin and old strata, and the favorable reservoir-cap assemblages for CO₂ storage are the Paleocene and Eocene. The CO₂ storage capacity of the salty aquifers in each secondary tectonic unit was calculated. Results show that the CO₂ storage in the D-level salty aquifers of the East China Sea shelf basin is 63.62 billion tons, among which the storage capacity in the Xihu Sag and the Jilong Sag in the eastern depression is the largest, both exceeding 10 billion tons, followed by the Oujiang Sag in the western depression, reaching 6.4 billion tons. Combined with the key storage factors, an index system for evaluating the suitability of D-class CO₂ geological storage in the East China Sea shelf basin was established. An index system for evaluating the suitability of D-level CO₂ geological storage in the East China Sea shelf basin was established. The suitability of each evaluation unit was also evaluated. Overall, Xihu Sag and Oujiang Sag have the best suitability for CO₂ storage and are favorable prospective areas for CO₂ storage in the East China Sea shelf basin.