The distribution characteristics and main controlling factors of the Chang 7 tight oil reservoir of Yanchang Formation in Bin-chang region,the southwest of Ordos Basin are summarized based on the comprehensive analysis of the geological conditions of hydrocar-bon source rocks,reservoir characteristics,source-reservoir-cap rock assemblage and migration driving force. It is shown that,Zhangjia-tan oil shale is the superior source rock of the Chang 7 formation,and the favorable reservoir mainly is the underwater distributary chan-nel sandstone of delta front. The physical property of the reservoir is poor,the porosity is 8. 8% in average,and the permeability is 0. 22 × 10 -3 μm2 in average. The reservoir belongs to the tight sandstone reservoir. The semideep-deep lake sedimentary environment leads to the poor lateral connectivity and the mudstone interlayers of the Chang 7 reservoir. Petroleum migrated vertically or laterally in short dis-tance under the driving of overpressure,and it accumulated in the favorable sandstone when the sealing ability of cap rock is sufficient. The accumulation and distribution of petroleum in the Chang 7 tight sandstone is controlled principally by the conditions of source rock, reservoir and cap rock. The development of source rock controls the distribution of reservoir,and the physical property of reservoir,the distribution of sandstone and the contact relationship between source rock and reservoir control the vertical distribution of the reservoir. The sealing ability of cap rock plays a decisive role in the distribution scale of the Chang 7 reservoir.%通过对鄂尔多斯盆地西南缘彬长地区烃源岩、储层特征、生储盖组合以及运移动力等综合地质条件进行分析,总结延长组长7致密油油藏分布特征及主控因素.结果表明,彬长地区延长组长7烃源岩以优质张家滩油页岩为主,有利储集体主要为三角洲前缘的水下分流河道砂岩,储层物性差,孔隙度平均为8.8%,渗透率平均为0.22×10-3μm2,属于致密砂岩储层.半深湖—深湖沉积环境导致长7储层横向连通性较差,纵向泥岩夹层多,石油在过剩压力作用下以垂向或侧向短距离运移为主,当封盖能力足够时,便在物性较好的致密储层中成藏.鄂尔多斯盆地延长组长7自生自储式油藏的形成和分布主要受烃源岩、储层和盖层三大因素控制,烃源岩的发育控制油藏展布,储层物性及砂体展布和源储接触关系控制着油藏分布层位,而封盖能力对长7致密油藏的分布规模起决定作用.
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