松辽盆地徐家围子断陷为受徐西、徐中两条断裂控制的箕状断陷,在徐南地区发现有超压气藏存在。利用地球物理和地质资料,从压实不均衡、生烃作用以及泥岩封闭等方面分析了该区的超压成因。研究结果表明,徐南地区地层为正常压实状态,不存在明显或可识别的欠压实沉积过程,地层压力在巨厚的泥岩封闭层下完好保存。生气作用是造成徐南地区气藏超压的主要原因,泥岩封闭为超压的保存提供了良好条件,压实不均衡作用对徐南地区的超压作用不明显。 The Xujiaweizi rifting in the Songliao Basin is a half-graben-like fault controlled by two faults in XuXi and Xuzhong. Excess gas reservoirs were found in the Xu Nan area. Using geophysical and geological data, the causes of overpressure in this area are analyzed from the aspects of uneven compaction, hydrocarbon generation and mudstone closure. The results show that the strata in Xu Nan area are under normal compaction status, and there is no obvious or identifiable undercompact deposition process. The formation pressure is well preserved under the thick mudstone seal. The main reason for the overpressure of gas reservoirs in Xu Nan area is the anger effect. Mudstone sealing provides a good condition for overpressure preservation. The effect of compaction imbalance on overpressure in Xu Nan area is not obvious.