鄂尔多斯盆地陇东地区长4+5油层组沉积相展布特征

为研究鄂尔多斯盆地陇东地区长4+5油层组的沉积相展布特征，开展了野外露头剖面和钻井取心的岩心观察、铸体薄片鉴定、重矿物测试、测井岩电关系分析等工作。结果表明：①陇东地区长4+5油层组的沉积主要受东北、西南和南部共三大物源区控制；②研究区主要发育3类沉积相，东北部为曲流河三角洲相，西南部和南部均为辫状河三角洲相，中部为湖泊相，可进一步将其划分为5类亚相和10类微相；③研究区长4+5油层组主要表现为"湖退-砂进"的沉积特征，长4+5₁小层沉积时相对于长4+5₂小层沉积时的湖盆面积较小，砂体规模更大；④相对于西南部和南部，东北部的物源供给更充分，多支水下分流河道汇聚于此，叠置连片分布的厚层砂体更为发育。该研究成果展示了陇东地区长4+5油层组的勘探潜力，可为下一步精细勘探提供借鉴。

Sedimentary facies distribution characteristics of Chang 4+5 reservoir in Longdong area,Ordos Basin

In order to study the distribution characteristics of sedimentary facies of Chang 4+5 reservoir in Longdong area of Ordos Basin,core observation,casting thin section identification,heavy mineral testing and log rockelectricity relationship analysis were carried out in outcrop profile and drilling coring. The results show that:(1)The deposits of Chang 4+5 reservoir in Longdong area are mainly controlled by three provenance areas in northeast, southwest and south;(2)Three types of sedimentary facies are mainly developed in the study area,inclu-ding meandering river delta facies in the northeast,braided river delta facies in the southwest and south,and lacu-strine facies in the central region,which can be further divided into five types of subfacies and 10 types of microfacies; (3)The Chang 4+5 reservoir in the study area is mainly characterized by "lake retreat-sand progradation". The lake basin area of Chang 4+5₁ sublayer is smaller than that of Chang 4+5₂ sublayer,but the scale of sand body is larger;(4)Compared with the southwest and south,the northeast has a more abundant supply of provenances and many underwater distributary channels converge. As a result,thick sand bodies with overlapping and continuous distribution are more developed. The research results show the exploration potential of Chang 4+5 reser-voir in Longdong area,which can provide reference for further fine exploration.