内蒙古开鲁盆地陆东凹陷九佛堂组层序地层格架与岩性圈闭

本文应用Vail层序地层学原理,综合利用地震、钻井、测井资料,对内蒙古开鲁盆地陆东凹陷早白垩统九佛堂组进行层序地层学研究,进而分析了层序格架内岩性圈闭的发育情况。研究发现,九佛堂组顶、底分别为上超面和削截面,内部可识别出初始湖泛面和最大湖泛面。在层序格架内九佛堂组发育扇三角洲、近岸浊积扇、远岸浊积扇和湖泊相。研究结果表明:九佛堂组为一个三级层序,可划分出低位、湖侵和高位体系域。九佛堂组岩性圈闭的发育类型及分布模式受层序格架及沉积相带控制。在盆地陡坡带主要发育构造-岩性圈闭,在深洼带主要发育砂岩透镜体圈闭,在盆地的缓坡带主要发育砂岩上倾尖灭圈闭。

Sequence stratigraphic framework and lithologic traps in the Jiufotang Formation, Ludong depression, Kailu Basin, Inner Mongolia

With the aid of Vail＇s sequence stratigraphic theory,the present paper deals with the examination of sequence stratigraphic framework and the development of the lithologic traps in the Jiufotang Formation,Ludong depression,Kailu Basin,Inner Mongolia on the basis of seismic data,cores and well logs. The top and basal surfaces of the Jiufotang Formation are found to be onlap surface and truncation surface,respectively,while the initial flooding surface and maximum flooding surface are observed within the Formation. The Jiufotang Formation encompasses the fan delta facies,nearshore turbidite fan facies,offshore turbidite fan facies and lake facies,and consists of one third-order sequence including lowstand,transgressive and highstand systems tracts. The trap types include structural-litholigic traps in the steep slope zone; the sandstone lenses traps in the depression,and sandstone thinning out-upward traps in the ramp zone.