Due to the heterogeneity and low permeability of most CO reservoirs in China

CO storage within a single reservoir is difficult to meet the demand for emission reduction. To achieve large-scale CO2 geological storage

multi-formation injection technology has been proposed to increase the amount of CO geological storage. To explore the main influencing factors on the caprock sealing performance under the condition of multi-formation CO2 injection

the seepage-stress coupling simulation analysis was carried out. Pore pressure

displacement

and incremental Coulomb failure stress (ΔCFS) are used as the basis for evaluating the caprock sealing performance. The tornado analysis method was used for sensitivity analysis to select the factors that have a significant impact on the caprock sealing performance. The research results indicate that the more injection layers

the smaller the displacement

pore pressure

and ΔCFS of the caprock

and the better the caprock sealing performance. However

if the number of layers exceeds 3

the efficiency increase brought by the number of layers will no longer be significant; The main controlling factors for the sealing performance of the caprock include the Poisson’s ratio and Young’s modulus of the caprock

thickness and permeability coefficient of the reservoir

and injection rate; When the thickest caprock is located at the topmost part of the entire formation

the caprock sealing performance is the best

producing the smallest vertical displacement

pore pressure

and ΔCFS.