南海北部陆坡深水曲流水道的识别及成因

Architecture and Origin of Deepwater Sinuous Channel on the Slope of Northern South China Sea

深水水道是深水沉积体系中重要的组成单元,其作为潜在的油气储集体也被油气行业所关注。深水水道多处于深水环境下的沉积地层中,因此对于其直接的观测和研究都比较困难。基于近年新采集的多道2D和3D地震资料,利用相干时间切片、RMS均方根振幅、3D振幅可视化等地球物理手段对南海北部陆坡深水水道进行了识别和研究。该水道为更新世深水曲流水道,与来自中南半岛的浊流侵蚀有关,水道呈SW—NE向展布,侧向侵蚀特征明显。3D振幅可视化图显示该水道轴部为强振幅反射,推测为富砂充填,其余部分为弱振幅反射,推测为富泥充填,这点与世界已钻水道特征一致。深水曲流水道的形成过程和内部结构复杂,其内部砂体与泥岩常互层出现,泥岩的封堵作用会阻碍流体的流动或形成超压,同时也可起到良好的盖层作用,因此对于深水曲流水道的勘探和开发要重视这个问题。

The deepwater channel is one important element of deepwater sedimentary system,and is becoming more important to the oil industry for its potential hydrocarbon reserve. Most of the deepwater channels were buried in the submarine sedimentary formation,and are difficult to observe and study directly. Based on the new required 2D and 3D seismic data,this paper used attribute analysis technologies,likewise 3D ESP coherence time slices（ flattened on the seafloor） ,RMS and 3D visualization to realize and study the deepwater channel developed on the slope of northern South China Sea. This channel was a deepwater sinuous channel developed in Pleistocene period,and was formed by the turbidite flow from the Indo-China peninsula. The channel is SW-NE extend,the lateral erosional features is apparent. The 3D amplitude visualization map shows that the axis fill of the channel is high amplitude reflection,and was supposed to be sand-rich fill,the other part of the channel fill is low amplitude reflection,and was supposed to be mud-rich fill,which are similar with the deepwater channel drilled in the world. The deepwater sinuous channel has complex inner fill and composition architecture,the sand and shale layer are always interbedded,the shale layer could either hinder the migration of the flow and form overpressure or be a better seal to the flow,and we should pay more attention to this problem under the exploration and development to deepwater sinuous channel.