鄂尔多斯盆地铁边城地区三叠系延长组长4+5沉积相研究

铁边城地区位于鄂尔多斯盆地的中西部的鄂托克前旗—盐池—环县—千阳南北向隆起带东翼陡倾斜坡和东北翼宽缓斜坡的挟持凹陷带上,以岩性油气藏为主。其主力油层为三叠系延长组长4 5油层。以岩心资料为主,结合测井资料,综合分析了储层岩性特征、沉积构造及粘土矿物的组合形式等特征,认为铁边城地区长4 5期的主要沉积体系属于陆相河湖三角洲沉积体系,并且属于曲流河三角洲体系。发育的主要微相类型包括有水下分流河道、河口坝、远端砂坝、分流间湾、水下天然堤和水下决口扇微相。文中探讨了沉积相与油气聚集的关系,为储集相带的预测及下一步的勘探奠定基础,为大规模开发提供技术支持。

Study on the sedimentary facies of Chang4+5 of Yanchang Formation in Triassic in Tiebiancheng area, Ordos Basin

Tiebiancheng area is located in nip depressed belt on south-north hunch belt between eastern steep slope and east-north slow slope in Etuokeqianqi-Yanchi-Huanxian-Qianyang area,the middle and western area of Ordos Basin.The main oil-bearing formation is Chang4 5 reservoir of Yanchang Formation,Triassic.The litho logical character,sedimentary structure and grain-size distribution of the reservoir are analyzed based on core data and logging data,and it is held that land facies river and lake dominated delta system develops in Chang4 5, and belong to bend flow river dominated delta system.The main microfacies include submerged distributaries channel,mouth bars,distal bar,distributaries separate bay,submerged bank and submerged burst fan.The relationship is studied between sedimentary facies and oil-bearing characteristics of the reservoir.The result of the study provides the support for prediction of favorable facies belts of the reservoir and next exploration.