【摘要】 利用岩心、粒度、测井信息和重力流沉积理论,系统研究了南堡凹陷东部洼陷带东营组重力流沉积特征和沉积模式。该区重力流沉积砂岩常夹于灰色、灰黑色泥岩中,砂岩相发育,其中正递变层理(含砾)中-细砂岩相(S-3)、粉砂岩相(S-4)和块状层理中-细砂岩相(S-2)发育层数最多,块状层理含砾砂岩相(S-1)次之;S-2沉积厚度最大,S-1和S-3次之。按支撑和沉积机制,将本区重力流分为浊流、砂质碎屑流、颗粒流和液化流,其中砂质碎屑流以基质支撑、冻结块状沉积为特征。不同重力流发育程度有明显差异。从砂岩层数看,浊流最多,砂质碎屑流次之,颗粒流和液化流最少;从单期沉积厚度看,砂质碎屑流最大,平均为1.17m,浊流沉积最小,仅平均为0.25m。为了回避取心的局限性、弱化重力流成因,突出具有油气储集意义的砂层概念,开展了测井岩性解释,结果表明该区重力流沉积为细砂岩或粉砂岩,单层平均厚度2.94m,最大厚度可达9.5m,其中单井中厚度在3m以上的砂体可达22层、累积达107.5m。本区重力流沉积为滑塌成因,除了(扇)三角洲前缘斜坡的自然滑塌外,断层(地震)活动或间歇式火山喷发是其关键的触发机制;断层活动除了提供滑塌的动力外,还影响着其堆积场所和沉积的结构。更多还原

【Abstract】 Sedimentary characteristics and depositional model of Dongying Formation in depressed belt of eastern Nanpu Depression were studied based on core,grain size and logging data.The gravity flow sediments,characterized by richness of sandstone lithofacies and lack of conglomerate ones,always interbedded with gray or deep-gray mudstone.According to beds’number,normal graded bedding sandstone(S-3),siltstone(S-4) and massive bedding sandstone(S-2)were the most developed ones,and the massive bedding pebbled sandstone(S-1)took the second place.However,S-2takes the first place in thickness,S-1and S-3took the second one.Considering supporting and depositional mechanism,sediment gravity flows in studied area may be divided into four types,i.e.,turbidity flow,sandy debris current,grain current and liquefied current,and specially,sandy debris current was supported by matrix and deposited by frozen massive mode.Every gravity flow developed differently on large scale.According to sandstone beds’number,turbidity flow took the first place and sandy debris flow the second one.Considering deposition thickness of single gravity flow,sandy debris flow took the first one with an average of 1.17m,and the turbidity flow deposit took the last one with an average of 0.25mwhich showing turbidity flow usually was very thin.In order to reduce the limit of cores and ignore the effect of different flow types on sandstone size,which decided their importance for hydrocarbon exploration,logging data were used in litho-interpretation.Interpretation results showed that the gravity flows’ sediments included fine sandstone and siltstone with an average thickness of 2.94mand a maximum thickness of 9.5mfor a single bed.Among them,there were 22single sandstone beds with over 3mthickness,which had a total thickness of 107.5m.Basically,the sediment gravity flows were sprung by sediments’slump on the delta front slope in studied area.During the processes,earthquake movements and intermittent volcano eruptions,besides natural sediments slump when the angle of delta front slope overrun the critical slope angel,brought the key dynamical mechanisms.Besides,faulting played an important role not only in providing accumulation space but also in deciding the depositional architecture.更多还原