泥岩底辟型微盆地中的深水水道沉积构型：控制因素及其作用机理

Deep-water channels are important exploration and development targets for the whole world at present. However, as of now we don't know much about control factors and the corresponding action mechanism of their sedimentary architecture which are complicated, and these increase the drilling disk and the difficulty of reservoir development. The project, taking the shallow-layer high resolution 3D seismic data of West Africa continental slop as a prototype model, will focus on the control factors and its action mechanism of sedimentary architecture of deep water channels, on the basis of the combining method of quantitative seismic geomorphology and sedimentary architecture analysis. This project will discuss external geometries and internal patterns of deep-water channels with different hierarchical scales, and establish their corresponding architecture models. Meanwhile, geometry parameter of submarine channel architectural unites will be measured and analyzed quantitatively, and by this way, we will attempt to reveal the internal cases and their controlling mechanism of channel sedimentary architecture unites. In addition, terrain slope which can reflect the relief of channel elements will also be surveyed, and the coupling and connection of those parameters with geometry ones of deep-water channel will be made. And then the external cases and their controlling mechanism to deep-water channel depositional pattern will be further studied.

作为当今油气勘探开发的重要目标，深水水道的沉积构型样式复杂多变，其控制因素和相应的作用机理目前尚无定论，这大大增加了该类油气藏的钻探风险和开发难度。为此，本项目拟以西非陆坡区典型泥岩底辟型微盆地为例，以近海底高频地震信息为原型，以深水水道沉积构型的控制因素及其作用机理研究为主线，以定量地震地貌学和沉积构型相结合的研究方法为桥梁，探讨不同层次水道单元的空间几何学特征及其组合关系，认知深水泥岩底辟型微盆地中的水道沉积构型系列模式；同时，通过对水道单元几何形态定量控制参数的分层次测量和分析，探究深水水道内部各层次构型单元的相互控制关系，揭示水道构型发育的内因及其作用机理；此外，提取能够反映各层次构型单元沉积前的地形坡度参数，结合地貌形态特征，探索水道单元几何形态定量控制参数与地形坡度、地貌形态之间的耦合和关联，进而揭示水道构型发育的外因及其作用机理。

作为当今油气勘探开发的重要目标，深水水道的沉积构型样式复杂多变，其控制因素和相应的作用机理目前尚无定论，这大大增加了该类油气藏的钻探风险和开发难度。为此，本文以尼日尔三角洲盆地陆坡区典型泥岩底辟型微盆地为例，以近海底高频地震信息为原型，以深水水道沉积构型模式研究为主线，以定量地震地貌学和沉积构型相结合的研究方法为桥梁，探讨了不同层次水道单元的空间几何学特征及其组合关系，认知了深水泥岩底辟型微盆地中的水道沉积构型系列模式，探究了各层次构型单元形态学特征参数间的相互控制关系，揭示了不同层次深水水道沉积构型演化的过程及控制因素。这一研究不仅对深水沉积学的发展具有较大的理论意义，而且对高效开发深水水道油气藏具有重要的实际意义。. 针对水道体系，认为可分为限制性、半限制性和非限制性三个大类；水道体系内部复合水道间存在垂向和侧向两种类型的叠置；揭示了地形坡度与水道体系类型和规模的耦合与关联，陡坡段（坡度大于1°）主要发育限制性水道体系，缓坡段（坡度0.5°-1°）主要发育半限制性水道体系，平坦段（坡度小于0.5°）主要发育非限制性水道体系；随着地形坡度的增大，水道体系宽度减小，深度增加，宽深比减小。. 针对复合水道，认为可分为下切式和包络式两类；复合水道内部单一水道间存在侧向和沿古流向的两类迁移；揭示了地形坡度对下切式复合水道的控制，随着地形坡度的增加，下切式复合水道的弯曲程度会迅速降低，宽度减小，下切深度增大，宽深比减小，外部形态会由“宽浅型”向“窄深型”演化，内部单一水道由侧向叠加向垂向切叠样式演变。. 针对单一水道，提出了“非河流注入型”单一水道的成因类型，分为决口改道和断层触发两类成因；揭示了决口改道式单一水道形态学演化的控制因素，在复合水道限制段，单一水道主要受控于复合水道，而在非复合水道限制段，主要受控于地形坡度，坡度越大，单一水道的曲率、宽度和宽深比均越小，而深度越大。