Potential for CO2 storage in shale basins in China.

• It maps the CO 2 storage potentials in shale basins in China comprehensively. • Both shale oil and gas basins are quantitatively estimated via different equations. • Basins are classified into three tiers for carbon storage with varied time scales. • The equations for the estimations of CO 2 storage potentials are optimised. • The density variation of CO 2 at different conditions was considered. China is the second largest shale gas and oil producing country possessing large and significant shale basins, and it is also one of the top carbon emitting countries. Therefore, there is significant potential to store CO 2 in shales in China to remove the carbon emission and enhance and gas recovery simultaneously. This research provides a comprehensive prediction of potentials of CO 2 storage in major shale gas/oil basins in China based on most recent publications where density variation of CO 2 at different subsurface conditions is considered and the different stages of development are classified. We optimise the calculation equations for shale gas and oil respectively, and further classified the three tiers (i.e. commercial, potential and possible reservoirs) in the calculation to prioritise the sequestration site selection. A total of around 6194 Gt, CO 2 sequestration in shales, including 172 Gt for commercial, 849 Gt for potential and 5147 Gt for possible storage, equivalent to a total of 620 years' carbon emissions in China is expected. These can be realised in around 20 years, 20–50 years and 50–100 years respectively. For future applications, more concerns should be on the evaluation criteria of sequestration sites in shales, CO 2 fracturing mechanisms and potential leakage, multi-phase seepage and reactions, and environmental monitoring systems. As a comprehensive assessment of potentials of CO 2 storage in shale basins in China, this paper will provide an important guide for future academic studies, industrial operations and government policy making. [ABSTRACT FROM AUTHOR]