南沙海域大中型油气田分布与油气地质特征

Distribution and Hydrocarbon Geological Characteristics of Large and Medium Fields in Nansha Sea Area

在广泛调研国内外相关资料的基础上,收集IHS、C&C、USGS数据库最新的钻井、油气田资料,系统分析了南沙海域大中型油气田及其成藏要素的分布与油气地质特征。南沙海域已发现大中型油气田主要分布在文莱—沙巴盆地和曾母盆地,无论是油气田数量还是油气储量规模均集中于中新世地层。主要发育裂谷(漂移)期海陆交互相煤系烃源岩、后裂谷期前三角洲泥岩两期烃源岩。主要沉积盆地具有海相生气为主、海陆过渡相和湖相生油为主的烃源岩分布特征,这也是"深水区富气、浅水区富油"这一油气分布规律的物质基础。储集层受区域构造演化和沉积环境控制,具有分带特征,表现为"外带老(上渐新统—下中新统)、内带新(中、上中新统)"。大中型油气田分布具有"外带以砂岩油气藏为主、内带以碳酸盐岩气藏为主"的特点。

Based on the extensive survey of relevant researches at home and abroad, and the latest drilling, oil＆gas felds informa-tion from IHS, C＆C, USGS database, the authors systemically analyzed the distribution and hydrocarbon geological characteristics of large and medium felds in Nansha sea area. Large and medium oil and gas felds discovered mainly in Brunei-Sabah and Zengmu Basins in Nansha sea area. Both the number of oil and gas felds and the size of hydrocarbon reserves are concentrated in the Mi-ocene. There are mainly two types of source rocks, i.e. coal measures developed in the marine-terrestrial facies of rifting （drifting） period and the mudstones of prodelta facies in post-rifting period. The distribution of source rocks in the main sedimentary basins are characterized by the fact that the source rocks of marine facies are gas prone and those of the transitional and lacustrine facies are oil prone, which constitutes the material base of “deep water area rich in gas, shallow water area rich in oil”. Controlled by the regional tectonic evolution and sedimentary environment, the distribution of reservoir rocks reveals the characteristics of “older reservoir （upper Oligocene to mid-lower Miocene） in the outside belt, younger （mid-upper Miocene） in the inside belt”. The distribution of large and medium oil and gas felds also exhibits the regularity of “sandstone oil and gas reservoir in the outside belt, carbonate gas reservoir in the inside belt”.