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东濮凹陷构造特征与断块群成藏条件分析

Analysis of Structural Characteristics and Reservoir Condition of Fault Blocks in Donpu Depression

【作者】 李继东

【导师】 郑浚茂;

【作者基本信息】 中国地质大学(北京) , 能源地质工程, 2008, 博士

【摘要】 东濮凹陷是典型的复式油气分布区,油气富集与构造因素有十分密切的关系,构造特征的认识对提高成藏规律的认识、寻找新的含油气区块、提高勘探效益起着关键性的作用。以构造分析为主线,应用断块群的概念和研究思路,分区带、分类型重点解剖不同的断块群,建立东濮凹陷断块群油气藏成藏模式,预测可供钻探的断块群圈闭分布区,指导勘探部署决策。1)系统分析了东濮凹陷的盆地结构,总结了古近系构造具有东西分带、南北分区、上下分层的基本特征,总体上构成“两洼一隆”的构造格局。采用复合划分原则将东濮凹陷划分为包括5个构造带、3个构造区、15个次级构造单元。认为凹陷东西分带是受NNE向基底主干断层控制,而兰聊主断层作为主边界断层的产状沿走向的变化导致了凹陷的南北分区。2)根据断距大小和对沉积的控制作用,将东濮凹陷的断层划分为三级。盆地北区以多米诺式正断层为主干断层的伸展连锁断层系统为主,盆地中区以铲式正断层控制的连锁断层系统为主,盆地南区以坡坪式主干断层控制的连锁断层系统为主要特征。3)分析了东濮凹陷伸展连锁断层系统的形成和演化,受连锁断层系统中主干断层的几何学、运动学特征的影响在不同区段、不同构造部位形成各种样式的复杂断块群。从南北分区上看,盆地中北区以雁列式展布的断层为特征,南区则为平行式断层组合为主;从东西分带看,兰聊断层带以铲式扇组合为主,中央低凸带以“X”型交叉断层组合为主,西部斜坡带以反向断阶带及其主干基底断层与盖层断层的“y”型断层组合为主。4)用构造物理模拟方法分析了不同区段盆地构造剖面的形成和演化过程。提出了地幔底辟和深断裂带右旋走滑位移两种动力机制联合作用主导了东濮凹陷的新生代应力场演化的构造动力学模式。东濮凹陷新生代盆地演化经历了两个大的阶段,即古近纪的裂陷阶段和新近纪-第四纪的拗陷阶段,整体上受兰聊断层控制。古近纪盆地演化可细分为四个阶段。5)对东濮凹陷复杂断块群油气藏从形成机制、类型划分、成藏模式进行了系统研究,提出了适合本凹陷的六大类复杂断块群油气藏划分方案:①断阶型复杂断块群;②叠合断阶型复杂断块群;③断阶转换型复杂断块群;④复式地垒型复杂断块群;⑤复式地堑型复杂断块群;⑥堑-垒叠置(相间)型复杂断块群。对该凹陷的勘探具有一定的指导作用。

【Abstract】 Donpu depression is a typical area of complex reservoir,Accumulation of oil & gas is related to structure closely. Knowing structural characteristics is the key to promote the understanding of reservoir forming laws, search new blocks with rich oil & gas and improve exploration benefit. Aiming at the exploration situation in Dongpu depression, from the view of tectonic analysis, applying the conception and thought of fault block group, it analyzes different fault block group by zone and type, establishes reservoir forming model of fault block group in Dongpu depression, predicts trap distributing area of fault block group for drilling, gives the direction of exploration.1) It systematically analyzes basin structure, sums up that paleogene structure has the basic characteristics of zoning from east to west, division from south to north, layering from upper to lower, forms a tectonic framework of“two sags and one uplift”as a whole. Applying the complex dividing rule, the Dongpu depression is divided into five structural zone, three structural divisions and fifteen secondary structure unit. It analyzed the main character and controlling factor of each structure unit, consider that the east to west belt is controlled by main basement fault in NNE direction, and Lanliao main fault, as the main boundary fault, its occurrence change along trend lead the division from south to north.2) Based on fault displacement and its control action to sediment, fault of Dongpu depression is divided into three levels. The northern area of the basin is mostly the extensional chain fault system with domino-like normal fault as the main fault, the centre of basin is mainly the chain fault system controlled by listric normal fault, and the southern of the basin is mostly the chain fault system controlled by ramp-flat main fault.3) On the basis of the extensional structure theory in rift-depression basin, it analyzes forming and evolution of extensional chain fault system in Dongpu depression, influenced by geometry and kinematics characteristics of the main fault in the chain fault system, it formed various complex fault blocks in different section and different tectonic position. Form south to north, normal fault in the northern area of the basin is mostly en echelon fault, in the southern area is mainly parallel fault assemble; from east to west, Lanliao fault is mainly listric fan assemble, the central low arch is mainly‘X”style fault assemble, the west slope is mainly‘Y”style fault assemble composed of reversal fault bench zone and its main basement fault and cap fault.4) Applying structure physical modeling method, it analyzes forming and evolution of basin structure profile in different section. It indicates that two dynamical mechanisms of mantle diaper and right-lateral strike slip in deep faulted zone lead tectonic dynamics model evolved in Cenozoic stress field of Dongpu depression. Cenozoic basin evolution of Dongpu depression experiences two great stages, that is Paleogene rifting stage and Neogene-Quaternary depression stage, as a whole controlled by Lanliao fault. Paleogene basin evolution can be subdivided into four phases.5) It systematically studied the forming mechanism, classifying type and forming patterns of hydrocarbon reservoir of complex fault blocks in Dongpu depression and divides the reservoir into six types:①fault bench type;②superimposed fault bench type;③fault bench conversion type;④complex horst type;⑤complex graben type;⑥graben alternating with horst type. It basically perfects the complicated exploration theory of Dongpu depression and strongly instruct exploration.

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