深水水道沉积单元及演化分析

    Depositional Elements of Deepwater Channels and Their Evolution

    • 摘要: 近年来,深水水道已成为油气勘探的重要目标,加强深水水道内部沉积单元以及沉积演化的研究对于深水油气勘探来说至关重要。基于3D地震资料,利用地震属性、地震相等研究下刚果盆地深水水道的内部沉积单元及演化规律。研究表明,研究区深水水道发育底部滞留沉积、水道侧壁滑塌沉积、侧向加积体、堤岸沉积、废弃水道5种沉积单元。深水水道形成于复杂的多期侵蚀-充填过程,纵向演化可划分为水道过路侵蚀、侧向迁移水道、高弯度垂向加积水道、水道堤岸复合体和废弃水道5个阶段,各个阶段水道内充填结构和水道平面展布特征呈现有规律的变化。水道的5个演化阶段是一个水道完整的演化模式,海平面变化、重力流供给、陆坡均衡剖面等共同控制着深水水道的演化。

       

      Abstract: Deepwater channel deposits have been a kind of significant exploration target in recent oil and gas exploration. To study the depositional elements of the deepwater channels and their evolution has, therefore, become an important task for geologists. In this paper, deepwater channel elements of the Lower Congo Basin were selected as cases for study, based on seismic attribute maps and seismic facies analysis from 3D seismic data. The integrated analysis reveals that channels filling deposits consist of five elements, including basal lag deposits, slump deposits, LAP, levee deposits, and abandoned channels from bottom up. Each channel suffered an evolution of five stages, i.e. channel incision, lateral amalgamation, aggradation, levee deposition and abandonment with time. The evolution of channels is controlled by sea-level fluctuation, development of gravity flow and slope equilibrium.

       

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