Cap rock is the most important geological structure in CO

2

storage

and the characterization method of its sealing capacity is a hot research topic at present. Aiming at the problem of evaluating the sealing ability of caprock

based on the theory of coupling parallel capillary bundle and DLVO（microscopic force of charged surface passing through liquid medium）

considering slip effect and water film effect

the theoretical calculation method of caprock breakthrough pressure is established

and the accuracy is verified with experimental data. The variation of breakthrough pressure with slip length and effective capillary radius is studied by analyzing the i

nfluencing factors. The results show that the relative error between the calculated breakthrough pressure and the experimental data of six core samples is between 0.317 % and 10.800 %. The smaller the slip length and the larger the effective capillary radius

the smaller the breakthrough pressure.