Présentations Colloques

Oral Presentation
Session 5.03: CO2 storage in deep saline aquifers and potential impacts on shallow aquifers
Li Qi
Multilevel U-tube monitoring of shallow aquifers for CO2 geological storage at the Shenhua CCS demonstration site in China
The carbon capture (CO2) and storage (CCS) is the crucial option to mitigate the large-scale emission of anthropogenic carbon dioxide in this century. However, Understanding the potential leakage risk of CO2 geological storage in the shallow aquifers is the first priority to gain the public confidence about the CCS technology before its commercial implementation around the world. ****As known, the Shenhua CCS demonstration project is the first full-chain CCS project in China which is capturing CO2 at a coal liquefaction plant and storing CO2 in an onshore deep saline aquifer in Ordos Basin, Inner Mongolia, and that around 300,000 tonnes of CO2 have already been injected. In this paper, we chose the Shenhua CCS demonstration site to focus on the monitoring of shallow subsurface and to evaluate the impacts of CO2 geological storage on the geoenvironment. At first, we installed novel U-tube sampling systems in eight wellbores at the demonstration site in order to periodically collect the samples of underground water and gas at fixed depths no more than 25 meters. Then, we conducted the hydrogeochemical analysis in the laboratory for the selected evaluation indexes of water and gas samples. After that, we also compared the analyzed results of the shallow surface with the ones of the deep monitoring well Zhongshenzhu #1 at more than 1000 m depth. Finally, we found some interesting results, e.g. there is no direct evidence for the possible leakage of the buried CO2 at the Shenhua CCS demonstration site. This study is not only helpful for the understanding of short to long- term environmental impacts of CO2 geological storage but also providing the support for the selection of reasonable evaluation indexes of underground water and gas in the coming post-closure monitoring of the Shenhua CCS demonstration project.**