Organization
SINOPEC Jiangsu Oilfield Branch Company, Yangzhou, Jiangsu 225009, China
摘要
苏北盆地古近系阜宁组二段（E1f2）发育两套富有机质页岩，分布广泛，油气显示丰富，页岩油形成条件有利。通过对大量岩心及薄片的观察，结合系统的有机地球化学、全岩X-衍射及微量元素测试资料，研究了苏北盆地E1f2两套富有机质页岩特征及沉积环境。苏北盆地E1f2两套富有机质页岩特征截然不同，其中第一页岩层（E1f2页1）以深灰色块状含灰泥岩和硅质泥岩为主，微显层理；页岩有机碳含量平均介于2.21%~3.41%，有机质类型以Ⅰ型为主。第二页岩层（E1f2页2）为灰黑色油页岩与纹层状含云、含灰泥岩、泥云岩、泥灰岩互层，纹层发育，有机碳含量平均介于2.02%~2.99%，有机质类型以Ⅰ型为主。苏北盆地E1f2沉积古气候经历了自半干热、还原、半咸水环境向干热、强还原、盐湖环境，再向温湿、氧化、淡水环境演化的过程；富有机质页岩形成于强还原、干热、咸水环境向氧化、温湿、正常淡水环境过渡的最大湖泛面附近，其中E1f2页2形成于强还原、干热的咸水—盐湖环境，E1f2页1形成于强还原、半潮湿—半干热的半咸水环境。沉积环境演化，造就了E1f2泥页岩层间及富有机质页岩内部岩性、电性及烃源岩品质的差异。
Abstract
Two sets of organic-rich shales are developed in the second member of Funing Formation (E1f2) in the Subei Basin, which are E1f2shale 1 and E1f2shale 2. They are widely distributed, with rich shows and favorable shale oil conditions. Based on core and thin section observations, and combined with systematic organic geochemistry, X-ray diffraction and trace element analyses, the characteristics and sedimentary environment of the organic-rich shales were studied. The characteristics of the E1f2shale 1 and E1f2shale 2 are totally different. The E1f2shale 1 mainly consists of dark gray blocky limestones and siliceous mudstones, with slight bedding, 2.21%-3.41% organic carbon content, and type I organic matter. The E1f2shale 2 mainly consists of dark oil shales and dolomitic mudstones, calcite mudstones, muddy dolomites and muddy limestones, with laminar bedding, 2.02%-2.99% organic carbon content, and type I organic matter. The sedimentary palaeo climate of E1f2 has experienced semi-arid, reducing, brackish water, to dry, strongly reducing, salt lake, and to warm humid, oxic, freshwater in the Subei Basin. The organic-rich shales were formed in the transition formations near the maximum flooding surface, between strongly reducing, dry and hot, saltwater environments and oxic, humid, normal water environment. The E1f2shale 2 was formed in a strongly reducing, dry and hot, salt lake environment, while the E1f2shale 1 was deposited in a strongly reducing, damp to semi-arid and brackish water environment. Sedimentary environment evolution resulted in the differences of lithology, electrical properties, and quality of hydrocarbon source rocks, occurring in the muddy shale interlayer and internal organic-rich shale.
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