柴达木盆地断裂特征及其对油气分布的控制作用

Faulting Characteristics and Effects on Hydrocarbon Distribution in Qaidam Basin

基底断裂决定了基底构造格架和盆地的构造演化和沉积发育,盆地断裂分级控制作用明显,一级断裂控制着盆地的构造演化和沉积发育;二级断裂是划分构造单元和控制烃源岩区的重要界线;三级断裂明显地控制了各类构造圈闭带的形成和分布;四级断裂控制了局部构造圈闭的发育和演化;五级断裂对构造圈闭起破坏作用或将构造圈闭复杂化。共发育4类6种成因类型的断裂,它们控制了8种成因特征的构造圈闭类型,其中断展背斜、冲起构造和断滑背斜是最重要的油气圈闭类型。柴达木盆地腹地断裂构造带发育,目前勘探程度低,油气潜力大,位于烃源岩中心或附近的裂缝发育圈闭(带)是取得勘探重大突破的最有利目标。

The basement structural framewor k ,evolution and sedimentary development in Qaidam basin are all controlled by t he basement fault.The controlling roles of basinal fault can be divided into t he five classes:Class I fault controls the structural evolution and sedimentary develop-ment;Class II fault is as key boundary line for classification of the structural units and for controlling source rock provinces;Class III fault con-trols the formation and distribution of various structural traps;Class IV fau lt controls the development and evolution of local structural traps;and Class V fault is of destroy roles to the structural traps or make the structural traps complicated.There exist four types of faults or six original types of faults ,which control eight original types of structural traps,in which the most sig nificant traps are fault-extending anticline,thrust structure and fault-slip ping anticline ones.In the hinterland of this basin,there are developed fault structural belts with great hydrocarbon po-tentials and low extent of explorat ion efforts.The study shows that the trap belts with developed fractures in th e center or surroundings of the source rocks will be the most favorable targets for breakthrough of exploration.