南海始新世海相地层分布及油气地质意义

采用古生态学及沉积学方法, 对南海北部深水区BY7-1-1井及L29井特定层段进行细致研究.通过有孔虫、孢粉藻类分析及沉积学分析, 证实南海北部白云深水区在晚始新世即出现滨浅海相沉积环境, 确定了南海北部最早接受海相沉积的时间.始新世海相地层在南海北部主要分布在台西及台西南盆地中, 并在晚始新世扩展到珠江口盆地白云凹陷.在南部分布较广, 曾母盆地、北康盆地、礼乐盆地及巴拉望盆地中均有始新世海相地层分布.南海始新世海相地层的分布受制于新南海扩张及古南海的消退, 以晚始新世为时间节点发生显著变化, 总体上分布范围增大, 反映该时期南海拉张和断裂活动的加剧.南海始新世海相地层具有良好的油气潜力, 在部分盆地中形成了优质的烃源岩与储层, 珠江口盆地白云深水区晚始新世海相地层的发现, 对南海深水海相油气勘探具有积极的参考作用. 

Distribution and Petroleum Geologic Significance of Eocene Marine Strata in the South China Sea

By means of paleontology and sedimentology, we conducted a study on specific intervals of wells BY7-1-1 and L29, which located in the deep-water area in northern South China Sea. The results from analyses of foraminifera, algae sporopollen and sedimentology, revealed that the sedimentary environment of Baiyun deep-water area in northern South China Sea during the Late Eocene belonged to littoral and neritic facies. This finding also confirmed the time when marine sediments first deposited in northern South China Sea. The distributions of marine strata during Eocene in northern South China Sea were mainly located in Taixi Basin and Taixinan Basin, and in Late Eocene the area of marine strata spread into Baiyun Sag of Pearl River Mouth Basin. The distribution of marine strata during Eocene in souther part of South China Sea was dissimilar to the north. The marine strata were widespread in Zengmu Basin, Beikang Basin, Liyue Basin and Palawan Basin etc.. The distribution of marine strata during Eocene in South China Sea is the combine effects of both the spreading of South China Sea and the shrinking of Proto-South China Sea. The marine strata distribution in E-M Eocene was quite different from Late Eocene with the area of marine strata enlarged as a whole. This reflects the aggravation of tension and fault movement in that period. The marine strata of Eocene in the South China Sea are provided with high petroleum petential. In some basins of this area it turns out to be great source rocks and reservoirs. Meanwhile, the discovery of Late Eocene marine strata in Baiyun Sag has significant reference value to the deep-water marine oil and gas exploration of South China Sea.