南海南部深水盆地构造与储层再认识

Review on the tectonic and reservoir of the deepwater basin in the southern South China Sea margin

基于近年来获得的探测新资料和已发表地球物理大剖面,重新厘定了南海南部大陆边缘深水油气盆地构造区划与油气系统。考虑南海张裂边缘近端和远端裂陷盆地的构造差异,我们认为远端陆缘深水盆地大多以NE-SW向张裂构造为特征,据此厘定了NE向张裂盆地构造,包括南安、曾母和礼乐等深水盆地。从油气储层系统来看,南沙海区存在着特色深水油气系统成藏模式,包括孤立碳酸盐台地、深水陆源碎屑沉积体系及陆架边缘三角洲的油气成藏模式;位于南海和古南海盆地之间的南沙地块,在古近纪就进入深水,远离陆地,深水陆源碎屑沉积体系相对不发育,相反,发育了一套巨厚的碳酸盐层序,可望形成独具特色的深水油气系统。南沙海区的这类潜在深水油气系统在南海北部未曾遇见,特别是古近纪陆源碎屑沉积体系和孤立碳酸盐台地油气系统的共生规律,必将丰富南海深水油气成藏理论,拓展油气勘探的新领域。

Based on newly acquired seismic data and previous published seismic data,we defined tectonic division and petroleum reservoirs of distal rifting basins in the southern South China Sea(SCS).Considering the differences between proximal and distal rifting basins,we propose that distal rifting basins,including Nanan,Zengmu,and Liyue basins,are mainly controlled by a extensional fault system of NE-SW striking.The hydrocarbon system in this region includes an isolated carbonate platform,deep-water turbidity systems,and shelf-margin delta systems.The distal rifting basin locating between the central basin of the South China Sea(SCS)and Paleo-SCS has been far away from continent and in deep-water as early as Eocene,where sediments are composed of a massive set of carbonates accompanying by deep-water terrigenous debris depositions.The hydrocarbon system in the southern SCS,especially a combination of shelf-margin delta deposition with the isolated carbonate-platform system,is different from that in the northern SCS.The results enrich petroleum theory and would help to identify new exploration targets.