基底断裂对松辽南部油气聚集的控制作用

Control of basement faults on hydrocarbon accumulation in Southern Songliao Basin

松辽盆地南部主要发育北东、北西和东西向 3组基底断裂 ,受不同大地构造环境控制 ,表现为伸展、走滑和挤压多种活动性质。以长岭凹陷、英台 四方坨子两个地区为例 ,分析了基底断裂对盆地区域构造格架、二级构造单元和次级断层形成与展布的控制作用。研究表明 :长岭凹陷发育北东向的基底断裂 ,控制北西向次级断层带的形成 ;英台 四方坨子地区沿嫩江存在一条北北西向的隐伏基底断裂 ,与北东向的哈拉海等基底断裂共同作用 ,使次级断层展布方向以南北向为主 ;北西、南北向次级断层对形成大面积断层 岩性油藏有重要控制作用 ;北西向基底断裂呈右行走滑性质 ,主要起到调节北东向断裂带延伸方向的作用 ;北东向断裂带。

There mainly developed three groups of basement faults including the strike orientations of north-east (NE), north-west (NW) and east-west (EW) in the Southern Songliao Basin. The basement faults were controlled by the different tectonic frameworks and stress fields in Mesozoic and had the activities of extension, left-lateral striking slip and compression actions. The regional structure framework and the secondary structure belts of the Southern Songliao Basin were strongly influenced and formed by the basement faults. The relationships between second-order faults developed in overlaying of the Cretaceous strata and basement faults developed in Yingtai-Sifangtuozi area and Changling Sag were analyzed. It is shown that the second-order faults play an important role in the formation of fault-lithological types of hydrocarbon accumulation in the Southern Songliao Basin. The NW striking second-order faults in Changling Sag were resulted from the left lateral action of NE striking basement fault, and the SN striking Tuodong fault in Yingtai-Sifangtuozi area was controlled by NE and NNW striking basement faults. Meanwhile, the NW striking basement faults, acting as tear faults, cut and separate the NE fault belts. The NE striking fault belts and SN striking fault belts near Nenjiang River may be the favorable plays to get new discovery of lithological reservoir in the near future.