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In addition to traditional gypsum salt rocks and shale rocks, many studies have confirmed that carbonate rocks also work as oil and gas seals. Breakthrough pressure is a characteristic parameter for the evaluation of the sealing ability of cap rocks. Different lithology types and lengths of carbonate rocks were subjected to breakthrough pressure measurement experiments at different temperatures, results showed that lithology, permeability and fracture development have obvious effects to rock characteristics. At the same temperature, sample length does not have a good correlation with breakthrough pressure, however, at different temperatures, the breakthrough pressure of most samples gradually decreases with the increase of temperature. Therefore, formation temperature has a non-negligible effect on the sealing ability of cap rocks. It is a key factor that needs to be considered for the evaluation of the sealing capacity of cap rocks. The carbonate rock with a high argillaceous content has better sealing capacity under high geothermal conditions.