松辽盆地三肇凹陷多边形断层系的油气成藏意义

松辽盆地三肇凹陷白垩系中发育了大量规模不等的断层，一般认为大断层是油气运移的重要通道，对小断层研究较少。小断层在平面上相互交织形成多边形的形态，还具有平面延伸长度小、断距小、倾角大的特征，综合分析认为这些小断层为多边形断层系。三肇凹陷多边形断层系发育广泛，平面上遍布整个凹陷，垂向上在扶杨油层和葡萄花油层中均有发育。研究表明多边形断层系有着重要的油气成藏意义：多边形断层系是扶杨油层的主要运移通道，控制着油层的分布，广泛发育的多边形断层系是扶杨油层平面连片的主要原因；大断层和多边形断层系均是葡萄花油层的运移通道，其中多边形断层系在葡萄花油层的油气运移过程中起分流作用，对葡萄花油层的分布有一定的影响作用。

Petroleum Accumulation Significance of Polygonal Fault Systems in Sanzhao Depression,Songliao Basin

There are abundant faults with different sizes in Sanzhao depression, Songliao basin. Predecessors who think that the large faults were main migration pathway for Fuyang and Putaohua oil layers, neglect the petroleum significance of small faults. There are a lot of small faults in the Cretaceous of Sanzhao depression, characterized by polygonal planform geometry and small distribution length, small fault throw and big angle of dip. So it is suggested that the small faults are Polygonal fault systems(PFS). In the plane, PFS distributed in the whole depression; while in the vertical, it distributed both in Fuyang and Putaohua oil layers. And PFS played a significant role during the accumulation of reservoirs. PFS, as the main migration pathway of Fuyang oil layer, have controlled the distribution of the oil layer, and widely-developed PFS are the main reason for continuous distribution of oil layer. Large faults and PFS are the main migration pathway of Putaohua oil layer, among which PFS played a bypass role in hydrocarbon migration of Putaohua oil layer and has some influence on the distributiion of Putaohua oil layer.