准噶尔盆地昌吉凹陷西斜坡侏罗系层序地层特征

在对地震、岩心、钻井、测井及分析化验资料综合分析的基础上 ,研究了准噶尔盆地昌吉凹陷西斜坡侏罗系的层序地层特征。结果表明 ,工区内侏罗系本身构成了一个由低水位、湖侵和高水位体系域组成的二级层序 (超层序 ) ,超层序的顶、底界面分别是侏罗系与三叠系、侏罗系与白垩系的区域性不整合面。根据层序内局部不整合面的分布范围、地层叠置样式 ,识别出 4个三级层序。由于侏罗系沉积时期受振荡性构造运动的影响 ,三级层序的发展不完整。除了层序 1发育低水位和湖侵体系域外 ,其他 3个层序均由湖侵和高水位体系域组成。超层序的低水位体系域 (相当于八道湾组下段 )发育湿地扇扇前河流平原沉积体系。湿地扇辫状沟道中的粗粒碎屑岩是该区的有利储层 ,与上覆煤层或炭质泥岩配置可形成优质储盖组合。湖侵体系域发育三角洲或滨浅湖沉积 ,高水位体系域发育辫状河沉积。

Sequence stratigraphic characteristics of Jurassic in the western slope of Changji sag in Juggar basin

The coring data, well logging, seismic data and analytical data were comprehensive analyzed. The Jurassic sequence stratigraphic features of the western slope of Changji sag in Juggar basin were discussed. The Jurassic constructed a second order sequence on itself. Its boundaries are the regional unconformable sections differentiating Cretaceous above from Triassic below. According to the characteristics of the local unconformities and stromalite patterns within the second order sequence, four third order sequences were identified. The third order sequence was not developed conformably. Among the four sequences, the first one developed lawstand systems tract and lacustrine deposits, the others developed highstand systems tract and locustrine deposits. In the lowstand systems tract of the second order sequence, humid fan was deposited and developed coarse grained reservoirs. The transgressive systems tract developed the delta or lacustrine deposits, and the highstand systems tract developed braided fluvial deposits.