靖安油田上三叠统延长组长6段沉积相研究

Sedimentary Facies of Chang-6 Member of Yanchang Formation of Upper Triassic in Jing'an Oilfield

以5条剖面和17口井的岩心观察为依据,结合储集层岩性、沉积构造和粒度分析等方法对长6油层组进行了多级次旋回层序划分,建立了不同时间尺度的等时地层对比格架。分析了沉积相平面展布规律,认为靖安油田三叠系延长组长6段属湖泊三角洲沉积体系,构成主体的是三角洲前缘亚相。探讨了沉积相对储集层物性的影响,认为河口砂坝和水下分流河道沉积微相最为发育,是含油气性最好的砂体,已具备了形成大规模油气藏的地质条件,应成为今后勘探的重点。

Based on 5 profiles and 17 wells' core data, integrated with reservoir lithology, depositional structure and grain size analyses, the polycyclic sequence stratigraphic classification of Chang-6 member is made, and the isochronal formation correlation framework of different time scales is established. By analysis of the sedimentary facies in-plane through-going feature, it is recognized that Chang-6 member of Yanchang formation of Triassic in Jing'an oilfield belongs to lacustrine delta system which is dominated by delta front sub-facies. The effect of sedimentary facies on reservoir physical property is discussed. It is concluded that well developed depositional microfacies as channel mouth bar and underwater distributary channel are premium petroliferous sandbodies and provided with the geologic conditions for forming large-scale reservoirs. They should be considered as targets for further petroleum exploration.