全球被动陆缘深水勘探领域富油气特征及与我国南海被动陆缘深水区对比

Oil and Gas-Rich Features in the Passive Margin Deep-Water Exploration Areas Worldwide and Comparison with the South China Sea Passive Continental Margin Deep-Water

被动陆缘深水富油气区油气资源丰富、大发现接连不断,正逐渐成为全球油气勘探的新热点。2000-2007年全球被动陆缘深水区(>300 m)共发现33个大型油气田,占全球同期油气大发现的42%。南海北部海域、南海南部海域及东南亚地区等属被动陆缘类型,近年来在深水区也不断有新的油气田发现。对比分析了我国南海被动陆缘深水盆地与典型被动陆缘盆地的石油地质特征存在的差异,比如发育时间上我国南海较国外发育晚、时间短;在被动陆缘发育的4个典型阶段——前裂谷期、裂谷期、过渡期和漂移期中,裂谷期与过渡期发育明显不同;不同演化模式导致不同的沉积、成岩、热演化环境等;沉积层厚度差异较大,国外被动陆缘沉积层厚度可达上万米;大地构造环境造成油气疏导系统差异;双层结构发育的具体情况不同,使得膏岩岩层、上构造层烃源岩发育差异明显等。因此,寻找具有特殊地质条件(比如我国南海经历了特殊的洋盆扩张史,其南部挤压、北部拉张、西部走滑、东部消减)的深水海域;考虑生物礁储层比较发育的独特优势(比如南海北部的流花11-1生物礁大油田,地质储量1.64亿t,南海南部还有许多与生物礁碳酸盐岩有关的油气田),将是今后南海被动陆缘深水区油气勘探的重要方向。

Passive margin deepwater areas are rich in oil and gas resources,and often have great discoveries,which has become a new concern for global oil and gas exploration.Totally 33 large oil and gas fields were discovered in the global deep-water passive margin（300 m） in 2000-2007,accounting for 42% of the discovery in the world over the same period.Northern South China Sea,Southeast Asia,southern South China Sea are the passive continental margin type.In recent years new oil and gas fields are also found in the deep-water.This paper comparatively analyzes the different geological features of oil in the South China Sea deep basin with the typical passive continental margin basins.For instance the development time compared to overseas development of the South China Sea was late,and the time was short.Passive continental margin development falls into four typical stages： pre-rift stage,rift stage,the transition period and the drift stage,but the rift stage and the transition period are significantly different in China.Different evolutionary models lead to different deposition,diagenesis,thermal evolution and environment.Also great differences are found in sediment thickness.For example,foreign passive continental margin sedimentary thickness is up to ten thousand meters.The different development of specific two-layer structure resulted in the obvious difference of the gypsum rock formation and source rocks in the upper structural layer.Special favorable geological conditions revealed indicate that the South China Sea oceanic basin has experienced exceptional expansion in the history of the south compression,tension in northern and western strike-slip and east reduction.Comparative development of reef reservoir,such as the northern South China Sea reef Liuhua 11-1 oil field may also reflect great potential of the oil-gas resources.