藏北北羌塘坳陷中西部地区布曲组碳酸盐岩烃源岩分布特征

THE DISTRIBUTED CHARACTERISITIC OF MIDDLE JURASSIC BUQU FORMATION CARBONATE SOURCE ROCK IN MIDWEST AREA OF NORTH QIANGTANG DEPRESSION

依据典型剖面实测和辅助对比剖面观测,结合大量系统样品的测试分析,认为羌塘盆地北羌塘坳陷中侏罗统布曲组主要由一套厚度巨大的半局限潟湖相泥晶灰岩、泥质灰岩和潮坪相颗粒灰岩、膏盐岩、泥页岩等组成。碳酸盐岩生油岩主要为潟湖相暗色泥晶灰岩、泥质灰岩及泥灰岩。生油层在纵向上主要产于布曲组下段和上段;横向上具有从坳陷内部到坳陷边缘生油岩厚度逐渐减薄、有机碳含量变差的特点。布曲组生油层的分布特征明显受沉积相和海平面升降变化的控制。该分布特征的研究对评价盆地布曲组生油前景,寻找主要生油坳陷等都具有重要意义。

According to the typical section measured and the auxiliary correlation section observation,as well as massive system samples data analysis,we thought that the Middle Jurassic Buqu Formation in the North Qiangtang Depression is mainly composed of a set of thickness huge semi-restricted lagoon facies micrite,marl and the tidal flat grain limestone,the gypsolith,the mudstone and so on.The carbonate source rocks mainly is the lagoon facies dark color micrite and the marl.The source bed in on longitudinal mainly delivers its lower segment and the upside;on crosswise from the depression interior to the depression edge,source rock thickness attenuates gradually and the organic carbon content variations characteristic.The source bed distribution characteristic of the Buqu Formation is controlled by the sedimentary facies and the sea level fluctuation change obviously.Its distributed characteristic have the vital significance to appraise uncooked oil prospect and seek the main uncooked oil depression.