Assessing the potential for CO2 storage in shallow coal seams using gas geochemistry: a case study from Qinshui Basin, north China

Chen, B., Fang, L., Xu, Z., Stuart, F. M. , Li, G. and Xu, S. (2024) Assessing the potential for CO2 storage in shallow coal seams using gas geochemistry: a case study from Qinshui Basin, north China. International Journal of Greenhouse Gas Control, 132, 104063. (doi: 10.1016/j.ijggc.2024.104063)

Abstract

Shallow coal seams are a target reservoir for CO2 sequestration. So far efforts to trace CO2 sequestration by coal beds have largely focussed on short-term monitoring or theoretical modelling. To evaluate the feasibility of safe long-term storage of CO2 in shallow coal beds, we report the first systematic gas geochemical study at a shallow injection site in Shizhuang, Qinshui Basin, one year after CO2 injection ceased. The injected CO2 is isotopically distinctive and appears to be enriched in heavy noble gases (Kr and Xe). The high CO2 content and light δ13CCO2 of gases from production wells confirm the migration of injected gas to the northeast and east of the main injection well previously tracked by geophysical studies. The migration of injected gas to the southeast has not been identified before, and exceeds that to the northeast, implying that gas geochemistry provides a more robust method of tracking migration. Less than 1 % of the total injected CO2 has been extracted from production wells in the year since injection ceased. We estimate that the target coal seam in the study area can store about 0.08 billion tonnes of CO2. Scaling up we estimate that the Qinshui Basin has the potential to store about 19 billion tonnes of CO2. This is significantly more than previous estimates. This study demonstrates the importance of geochemical tracers in quantifying and monitoring CO2 sequestration and also implies that unmined coal seams have high potential for the long-term storage of CO2.

• Item Type: Articles
• Additional Information: This study is supported by the National Natural Science Foundation of China No. 42150710532 and No. 42103048.
• Keywords: CO2 leakage monitoring, CO2 storage potential, shallow coals, gas geochemistry, Qinshui Basin.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Stuart, Professor Fin

Creator Roles

Stuart, F.: Methodology, Writing – review and editing

• Authors: Chen, B., Fang, L., Xu, Z., Stuart, F. M., Li, G., and Xu, S.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: International Journal of Greenhouse Gas Control
• Publisher: Elsevier
• ISSN: 1750-5836
• ISSN (Online): 1878-0148
• Published Online: 10 January 2024
• Copyright Holders: Copyright © 2024 Elsevier Ltd.
• First Published: First published in International Journal of Greenhouse Gas Control 132:104063
• Publisher Policy: Reproduced in accordance with the publisher copyright policy