鄂尔多斯盆地延长组中部层序地层格架及有利储层分布

High-resolution sequence stratigraphic framework and distribution of favorable reservoirs in SQ3 sequence of Yanchang group in Ordos Basin

为理清鄂尔多斯盆地延长组中部层序地层格架与有利储层分布,在岩心、测井和地震资料综合解释的基础上,利用基准面升降等高分辨率层序地层分析方法,将SQ3层序划分为5个中期基准面旋回(MSC1—MSC5),建立了高分辨率层序地层格架。高分辨率层序地层单元沉积相构成与有利储层分布研究结果表明,SQ3层序有利储集区的分布受控于层序发育位置,MSC1旋回有利储层分布于辫状河三角洲前缘中部至湖盆边缘一带,靠近湖盆中心部位薄层透镜状油藏发育;MSC2—MSC4旋回有利储层主要分布于辫状河三角洲前缘中部至湖盆中心方向,水下分流河道砂体与烃源岩呈指状交互接触,油气成藏条件最为有利。

Based on the integrated analysis of core,well logging and seismic data,we take measures of high-resolution sequence stratigraphic analysis such as promotion and demotion of the base level to divide SQ3 sequence into 5 medium-term base level cycles and establish the high-resolution sequence stratigraphy framework to clarify the sequence stratigraphic composition and favorable reservoir distribution of central Yanchang group in Ordos Basin.Studies on the composition of the sedimentary faces in highresolution sequence stratigraphy units and the distribution of the sand body reveal that the favorable reservoirs distribution of SQ3 sequence is controlled by the position of this suit of sequence where it is developed.The distribution of the favorable reservoir areas in MSC1 circle ranges from the middle area of the braided river delta lips to the edge of the lake basin and the area which locates near the lake basin center that is featured with the occurrence of thin lentoid reservoirs,and the favorable reservoirs of MSC2 MSC4 circles mainly are mainly distributed in areas from the middle area of braided river delta lips to the lake basin center.The sand body of underwater division channel and hydrocarbons are finger contacted,which makes it perfect for hydrocarbon accumulation.