北部湾盆地乌石凹陷东部地区流沙港组烃源岩孢粉相特征及其意义

根据孢粉相研究方法,在明确有机碎屑组成的基础上,对乌石凹陷古近系流沙港组烃源岩的有机质来源、形成环境进行研究,并对烃源岩生烃潜力进行了评价。结果表明:流沙港组烃源岩形成于具有一定矿化度的微咸水湖至半咸水湖,流二段底部和顶部油页岩层段对应着湖泊发育的鼎盛时期;从流三段到流一段生源特征在垂向上表现为从混源到水生生物为主,再到混源,最后变为以陆相高等植物有机质为主;流沙港组烃源岩的生烃潜力受无定形有机质的含量影响最大,流二段尤其是其上下两套油页岩段无定形有机质含量最高,生烃潜力最大,流三段次之,流一段生烃潜力最差。
Using the palynofacies analyzing method,this article first studied the origin and formation environment of organic matter of the source rocks in Liushagang Formation of Paleogene, Wushi Depression, and then evaluated the hydrocarbon generation potential of the region.The results show that the source rocks originated from low salinity lakes, and the bottom and top of the El2 oil shale formation correlate with the culmination of the lakes. For the El3 and the mudstone of the middle part of El2, the biogenic origin is mixed. For the oil shale of El2, the biogenic origin is the aquatic organisms. Lastly for the El1, the biogenic origin is the higher plants. The hydrocarbon generation potential of the source rocks is mainly influenced by the amorphous organic matter(AOM) content of the oil shale of El2, whose AOM content is the highest, has the greatest hydrocarbon generation potential, the E13 takes the second place, while the El1 has the least potential