南海深水区盆地油气发现率极低,其中一个重要原因是对其油气成藏条件、特征及主控因素认识不清.结合南海区域地质背景,通过系统总结南海油气地质条件,分析南海海域已发现油气藏和含油气构造系统,并对典型油气藏进行解剖,将南海沉积盆地含油气系统从区域上划分为5类,这5类含油气系统对南海油气成藏特征与油气分布具有明显的控制作用.研究结果表明:①始新统湖相烃源岩含油气系统主要分布于南海北部内裂谷带断陷陆架区,坳陷区深层碎屑岩具较好的油气勘探前景;②下渐新统海陆过渡相烃源岩含油气系统主要分布于南海北部外裂谷带陆坡区,是目前南海油气勘探的主战场;③上渐新统海陆过渡相烃源岩含油气系统主要分布于南海南部陆架区,生物礁碳酸盐岩在该区勘探中要尤为重视;④中-上中新统海陆过渡相烃源岩含油气系统主要分布于南海南缘前陆碰撞带,深水区朵叶砂体具有较好的勘探潜力;⑤中新统陆源海相烃源岩含油气系统主要分布于南海陆坡深水区,预测该区域具有较好的成藏条件.%One of the reasons for the very low hydrocarbon discovery rate in the deep water basins in South China Sea(SCS) lies in the unclear understanding of the hydrocarbon accumulation conditions,characteristics and main controlling factors.Combining with the regional geological background in SCS,by systematic analyzing oil/gas geologic conditions,revealed reservoirs and hydrocarbon bearing structure systems,and typical hydrocarbon reservoirs,five types of petroleum systems are identified in the sedimentary basins in SCS,which obviously control the accumulation characteristics and oil/gas distribution.The study results conclude that:①The petroleum system of Eocene lacustrine source rock is mainly distributed in inner rift belt of northern shelf of SCS,and clastic rocks of deep layers of the depressions are of favorable exploration prospects;②The petroleum system of Lower Oligocene transitional source rock is mainly distributed in outer rift belt of northern slope of SCS,and also is the main exploration target at present;③The petroleum system of Upper Oligocene transitional source rocks is mainly distributed in southern shelf of SCS,with the reef carbonate being the focus exploration area;④The petroleum system of Middle-Upper Miocene transitional source rock is mainly distributed in the foreland collision belt of southern margin of SCS,with the lobe sandbodies in deep water areas having good exploration potential.⑤The petroleum system of Miocene terrestrial marine source rocks is mainly distributed in the deep water region of the slope of SCS,with good accumulation conditions being anticipated.
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