膏盐层在库车秋里塔格构造带构造变形及成藏中的作用

库车坳陷秋里塔格构造带发育古近系库姆格列木群和新近系吉迪克组两套膏盐层,这两套膏盐层对该区构造变形和油气成藏起了重要的作用。地震剖面揭示盐层的存在使得秋里塔格构造带构造上、下分层,盐上层主要形成盐推覆构造、逆冲断层、断层传播褶皱和盐核背斜等构造;膏盐层主要形成盐枕、盐焊接或断层焊接等构造;盐下层主要发生断层转折褶皱、背冲断块和逆冲断层等变形。膏盐层组成了该区主要的盖层,并与盐下储层组成了优质的储盖组合,对盐下油气藏的保存极为有利。膏盐层可以改善盐下储层的储集性能,而且膏盐层的塑性流动还可以吸收盐下构造应力,使得盐下构造圈闭在强烈的构造挤压中得以保存。

FUNCTIONS OF GYPSUM-SALT LAYER IN TECTONIC DEFORMATION AND HYDROCARBON ACCUMULATION OF HE QIULTAG STRUCTURAL BELT. KUQA DEPRESSION

There were two gypsum-salt layers in the Qiultag structural belt,Kuqa Depression,namely,the Paleogene Kumugeliemu Group(K1-2km) and Neogene Jidike Formation(N1j),which played an important role in structural deformation and hydrocarbon accumulation of the region.Several seismic sections across the Qiultag structural belt revealed that there developed different deformational patterns in the salt-overlying layer,the gypsum-salt layer and the salt-underlying layer,which resulted in three main structural layers occurred.The salt nappes,thrust faults,fault-propagated folds,salt core anticlines,etc.,were mainly developed in the salt-overlying layer.The salt pillows,salt-welding or fault-welding were formed in the gypsum-salt layer.The fault-bended folds,back-thrusted blocks,thrust faults,etc.,were mainly occurred in the salt-underlying layer.A good combination of reservoir and cover in the region consisted of the gypsum-salt layer,as a main cover,and the reservoir in the salt-underlying layer.The gypsum-salt layer improved the reservoir capability of the salt-underlying layer,furthermore,the gypsum-salt layer absorbed structural stress in the salt-underlying layer,so that the structural trap in the salt-underlying layer could be preserved in younger structural events.