新疆三塘湖盆地马朗凹陷侏罗系西山窑组沉积特征及沉积模式

在岩心观察的基础上,结合录井资料、重矿物分析及地震资料,对三塘湖盆地马朗凹陷西山窑组物源方向、沉积相展布及沉积模式进行研究。研究认为马朗凹陷西山窑组主要发育辫状河三角洲和湖泊相2种沉积相。西山窑组下段沉积时期,辫状河三角洲在湖盆北侧大面积分布,辫状河三角洲前缘的水下分流河道频繁改道、迁移,相互切割,叠置成厚20~50m连片分布的砂体。西山窑组上段沉积时期,马朗凹陷以湖泊相沉积为主,有小规模的辫状河三角洲发育,局部发育滩坝砂体。西山窑组沉积整体呈现出一个水进过程。分析化验数据表明,西山窑组砂岩以岩屑砂岩和长石岩屑砂岩为主,储集层胶结作用不强,以压实减孔为主,主要发育剩余粒间孔;储集层质量主要受控于沉积微相,水下分流河道砂体是最好的储集砂体。

Sedimentary characteristics and models of the Jurassic Xishanyao Formation in Malang Depression,Santanghu Basin,Xinjiang

On the basis of core observation,logging data,heavy mineral analysis and seismic data,the provenance direction,sedimentary facies and models of the Xishanyao Formation in Malang Depression of the Santanghu Basin have been reseached. The research suggests that there are braided river delta facies and lacustrine facies. In the early sedimentary time of the Xishanyao Formation,the braided river delta widely distributed in the north of the lake. The underwater distributary channel sandbodies and the mouth bar sandbodies,distributing in the braided river delta front,are the main reservoir. In the late sedimentary time of Xishanyao Formation,the lacustrine facies was the main facies type in Malang Depression.The small-scale braided river delta and the beach bar also distributed in this period. There is a transgression process in the Xishanyao Formation period. According to the test analysis data,the lithic sandstone and the feldspathic lithic sandstone are the main sandstone types in the Xishanyao Formation. The cementation of sandstone is not strong. The compaction is the main factor of decreasing porosity. The intergranular dissolution pore and the residual intergranular pore are the main effective reservoir space. The reservior quality is greatly influenced by sedimentary microfacies. The sandstone of the Xishanyao Formation belongs to low porosity and low permeability reservoir,and it is the effective oil and gas reservoir.