鄂尔多斯盆地砂质辫状河夹层特征——以苏东27-36密井网区为例

Characteristics of sandy braided river intercalations in Ordos Basin: taking Sudong 27-36 tight well area for example

鄂尔多斯盆地苏里格东区盒8下亚段属于砂质辫状河沉积,储层非均质性较强。依据岩心、测井、录井等资料,分析研究区砂质辫状河-三角洲平原沉积学特征,在构型分析的基础上,指出多级界面形式存在的夹层。依据夹层分布特征,将研究区夹层主要分为河道间夹层、心滩坝内夹层、心滩坝间夹层以及河道底部滞留沉积。综合分析研究区6个沉积时间单元内夹层的密度、频率、分布特征,指出夹层主要分布在研究区南部,北部和东部相对较少。通过对盒8下亚段砂体构型解剖,认为辫状河砂体连片发育,夹层的存在使得砂体各向连通性变差,夹层是储层非均质性的重要成因之一。

Lower Member of He 8 in eastern Sulige area belongs to sandy braided river deposits, and the reservoir heterogeneity is complex. According to the cores, log and well-log data, the sedimentlogical characteristics of sandy braided river delta plain in the study- area were analyzed; on the basis of configuration analysis, it was pointed out that the intercalations exist in multi-level interfaces. The intercalation is mainly divided into four types： intercalation between river channels, intercalation in a diara, intercalation between diaras and sediment retention at the bottom of the channel. The density-, fi＇equency and distribution characteristics of intercalations in six sedimentary units of 139 wells in the work area were comprehensively analyzed. The intercalations are mainly distributed in the southern part of the study area. Through the structural anatomy of the Lower Member of He 8, the braided river sand body- is contiguous, directions of sand body- connection become worse because of intercalations; and the intercalation is one of the important factors for the genesis of its heterogeneity.