西沙海域晚中新世深水水道发育特征及主控因素

Development characteristics and controlling factors of Late Miocene deep-water channels in Xisha Area

为明确西沙海域晚中新世深水沉积体发育特征及影响因素,根据二维和三维地震资料,结合区域构造背景,建立深水水道发育模式。结果表明:西沙周缘中新世发育两类不同物源类型的深水沉积体,一类是以越东水系陆源碎屑供源的深水水道,另一类是以西沙台地碳酸盐岩碎屑供源的深水水道。陆源碎屑供源的深水水道,主要受古地形和海平面升降的影响,水道的迁移性强,水道间存在相互切割的特征;碳酸盐岩碎屑供源的深水水道,主要受古地形的影响,以垂向加积为主,水道的迁移性弱。该结果对西沙周缘油气勘探中深水水道的识别与储层预测具有指导意义。

In order to clarify the development characteristics and controlling factors of the Late Miocene deep-water channels in the Xisha Area,based on 2D and 3D seismic data and regional tectonic,we established models of the deep-water channels.The results show that there were two types of deep-water channels of different provenance in Miocene in Xisha Area.One type is a deep-water channel that is fed by terrigenous debris from the Eastern Vietnamese drainage system,and the other type is a deep-water channel that is fed by carbonate debris from the Xisha carbonate platform.Deep-water channels fed by terrigenous debris are highly mobile due to the impact of paleotopography and sea level fluctuations,with the characteristics of mutual cutting between channels.The deep-water channels that supplied by carbonate rock fragments are mainly controlled by paleotopography and are dominated by vertical aggradation with weak mobility.The results have guiding significance for the identification of deep-water channels and reservoir prediction in oil and gas exploration in Xisha Area.