下刚果盆地A区块中新统深水水道沉积特征

    DEPOSITIONAL CHARACTERISTICS OF MIOCENE DEEPWATER CHANNEL DEPOSITS IN BLOCK A OF LOWER CONGO BASIN

    • 摘要: 重力流分支水道是下刚果盆地中新统发育的典型深水沉积单元之一。利用相干时间切片、RMS均方根振幅和3D振幅可视化等地球物理手段识别出工区内发育的深水弯曲水道,论述了复合水道砂体内部充填结构,精细刻画了深水水道砂体的内幕结构,并利用地质异常体处理与三维可视化技术相结合追踪出工区内发育的水道砂体,描述了其平面分布特征和储层特征。工区内主要发育高弯度重力流分支水道,根据深水水道充填成因分类将其进一步划分为侵蚀充填型和侵蚀—加积型水道复合体;大型侵蚀水道内部由多期充填,主要由滑塌形成的旋转滑块和碎屑流、叠置水道及水道—天然堤沉积组成;并在三维可视化中识别出了多期水道砂体,探讨了水道砂体的地震反射特征和测井响应特征。

       

      Abstract: The distributary channels of gravity flows are typical deepwater depositional elements well developed in the Miocene of the Lower Congo Basin. Advanced Geophysical technology, such as 3D ESP coherence time slices, RMS amplitude and 3D visualization, have been used to identify the deep-water meandering channels. The internal filling structures of the complex channel sand body are discussed and described in this paper. The channel sand bodies developed in the study area were traced through geologic anomaly with 3D visualization technique, and the plane distribution and reservoir characters were revealed. The high sinuous gravity flow distributary channels could be classified into 2 types, i.e. erosional and erosional/aggradational channel complexes, according to the filling pattern of the sediments. Large-scale erosional channel with multiphase fillings are composed of rotational sliding blocks, debris flow deposits, stacked channel and channel-levee deposits, which were recognized with 3D visualization. Their seismic reflection characteristics and logging responses were studied as well in details.

       

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