柴达木盆地北部基底岩性对上部地层构造演化及储集条件的影响

INFLUENCE OF BASEMENT LITHOLOGY ON THE STRUCTURAL EVOLUTION AND RESERVOIR CONDITIONS OF OVERLYING STRATA IN THE NORTH MARGIN OF CHAIDAMU BASIN

由于不同的基底具有不同的构造边界条件 ,而在受力时又最易在不同的基底边界附近集中应力 ,从而成为应力的释放带或释放区 ,所以造成了柴达木盆地北缘的基底岩性与上覆盖层构造单元有很好对应关系 ,晚印支运动、早燕山运动、早喜山运动、晚喜山运动、新构造运动在柴达木盆地北缘造成的影响都与盆地的基底岩性有关 ;由于柴达木盆地北缘基底与周边的阿尔金山、祁连山形成一个整体 ,而柴达木盆地北缘基底和周围山系主要由下古生界赛什腾群弱磁性的绿泥石石英片岩、绿泥片岩、大理岩等构成 ,母岩的性质控制着储层的岩石成分和岩石结构 ,从而使该区储层的物性较差。文章还指出 ,要加强柴达木盆地的基础地质研究 ,从宏观上把握规律 。

Because different basements have distinct structural boundary conditions, the stress may be easiest concentrated on the neighbourhood of different basement boundaries when they are forced, thus becoming of pressure release zone (or area), which caused a good corresponding relation between the basement lithology and the structural elements of overlying strata in the north margin of Chaidamu Basin. The influences caused by late Indo-China movement, early Yanshan movement, early Himalayan movement, late Himalayan movement and neotectonic movement, etc., in the north margin of Chaidamu Basin were related to the basement lithology. The basement of north margin in Chaidamu Basin can be connected with the A' erjinshan Mountains and Qilianshan Mountains around the basin, and the basement and surrounding mountain systems are composed of the chlorite quartz schists, chlorite schists and marbles, etc. Therefore the rock composition and texture of the reservoir are dependent on the properties of parent rocks, thus forming a bad petrophysical property in this region. In the paper, the authors also point out that it is necessary to strengthen the research on basic geology in Chaidamu Basin to hold on the rule macroscopically to ensure the success ratio in oil and gas exploration.