柴西地区构造样式与油气勘探领域

Structure styles in the West Qaidam Basin and its hydrocarbon exploration prospective

文中通过大量地质剖面解释成果,厘清了柴达木盆地西部地区喜马拉雅运动各阶段构造变形模式和构造样式,分析认为柴达木盆地西部构造演化具有阶段性和层次性,不同阶段、不同的卷入深度形成了不同的构造样式及油气圈闭类型,在单一构造样式研究的基础上,总结和提炼了主要构造叠加样式,通过分析生、储、圈的配置关系,阐明了油气勘探领域,并得出以下认识:①柴西地区经历了早、中、晚期喜马拉雅运动多期构造运动,喜马拉雅运动早期以局部伸展运动为主,发育伸展构造样式;喜马拉雅运动中期以压扭作用为主,发育压扭构造样式;喜马拉雅运动晚期以水平挤压为主,发育多种断裂相关褶皱样式。②多次构造运动的叠加产生了8种构造叠加样式,其中反转构造+同沉积背斜+断层传播褶皱具备很好的石油地质条件,也是最为成熟的油气勘探领域,双重逆冲+生长三角带是阿尔金山前带构造+岩性勘探的理想场所,同沉积逆断层+单斜断块与同沉积逆断层+对冲三角构造是围绕昆北和阿尔金构造带扩大碎屑岩有利储集相带及地层岩性圈闭勘探的有利区带,同沉积逆断层+断层传播褶皱+突发构造与古隆起(斜坡)+断层传播褶皱+生长三角带分别对深层非常规储层(裂缝与次生孔隙)和中、浅层岩性勘探具有重要的现实意义。

Based on interpretation of a great amount of geology data in the West Qaidam Basin,the structure deformation style and structural style of the different stages in Himalaya period have been clearly demonstrated in the paper.With different episodic tectonic evolutions of Western Qaidam Basin,the different structural styles and trap type have been formed in depth.The main tectonic stacking pattern is delineated based on single structure pattern analysis.Further exploration areas have been clarified by analyzing the relationship between oil & gas generation,storage,and trap.The following conclusions are obtained:A.The west of Qaidam Basin has been affected by the early,middle,late Himalaya period movements.Mainly with local stretching movement,the early Himalaya movement developed an extensional tectonic style.The middle Himalaya movement developed transpressional structural style.And with horizontal extrusion,the late Himalaya period developed a variety of fault fold styles.B.Eight styles of structure superposition were concluded by many times of such tectonic movements.The style of inverse structure + syn-sedimentary anticline + fault-propagated fold has the most advantages in petroleum geological conditions,and it may be the most mature oil & gas exploration area.The style of wedge shaped duplex overthrust + growth triangle has important instruction meanings for the exploration in Altun piedmont area.Around North Kun and Altun structural zones,the types of thrust fault of syndeposit + monocline block mountain and thrust fault of syndeposit + triangular structure are favorable clastic rock reservoir facies belts,and favorable lithological traps.The style of thrust fault of syndeposit + fault-propagated fold + pop-up structure and paleohigh(ramp) + fault-propagated fold + growth triangle have important practical significance for unconventional reservoir exploration in deep targets,and for lithological reservoir exploration in middle and shallow formations.