研究了徐家围子断陷登二段泥岩盖层发育特征 ,根据烃类气体、CO2 气体之间与水界面张力的关系 ,建立了一套评价CO2 气毛细管封闭能力的方法 ,并预测了徐家围子断陷登二段泥岩盖层毛细管封闭CO2 气的能力 ;根据空间分布特征和毛细管封闭特征 ,综合评价了徐家围子断陷登二段泥岩盖层 .结果表明 ,登二段泥岩盖层质量控制着徐家围子断陷CO2 的成藏与分布 ,整个断陷大部分地区有较强的封盖能力 ,局部地区为中等或差的封盖能力 . Based on the relationship between hydrocarbon gas and CO2 gas and water interfacial tension, a set of methods to evaluate the capability of CO2 gas capillaries was established. According to the spatial distribution characteristics and capillary sealing characteristics, the mudstone caprock of Deng 2 Member of Xujiaweizi Fault Depression was comprehensively evaluated. The results show that the quality of mudstone caprock of Deng 2 Member Controlling the accumulation and distribution of CO2 in the Xujiaweizi Fault Depression, covering most parts of the whole fault depression with strong sealing ability and in some areas with moderate or poor sealing ability.