南黄海盆地二叠系烃源岩孢粉相特征及其形成环境

以沉积环境控制烃源岩发育理论为指导,应用孢粉相分析方法,以南黄海盆地二叠系大隆组、龙潭组和栖霞组烃源岩层段为研究对象,对典型钻井剖面的孢粉及沉积有机屑进行系统的分析。根据沉积有机屑的丰度特征和组分类型,探讨三套烃源岩的形成环境,初步评价其生烃潜力。研究结果表明,利用孢粉相分析方法,可以有效地对高成熟海相烃源岩的生烃潜力和形成环境进行客观评价:栖霞组为缺氧远陆架沉积环境,以无定形有机质为主,水体分层缺氧,是烃源岩形成的有利环境;大隆组为缺氧和少氧的陆架环境,也较有利于烃源岩的形成,生烃潜力较栖霞组差;龙潭组煤质型有机质较为丰富,为充氧的陆架区,以陆源输入为主,沉积区水体较浅,含氧量高,不利于富氢烃源岩的形成。

Palynofacies Characteristics and Formation Environment of Permian Source Rock in South Yellow Sea Basin

The development of hydrocarbon source rock and its sedimentary environment are closely related.Based on the theory and the application of the palynofacies,we discussed the formation environment of the source rock of Permian Dalong Formation,Longtan Formation,and Qixia Formation in South Yellow Sea basin.By the systematic analysis of the pollen and the organic matter of the typical drilling profiles for their abundant characteristics and composition types, and combined with the plankton algae and the sign of organic matter of the favorable hydrocarbon source rocks, the hydrocarbon generation potential was evaluated finally in this article. The results show that the hydrocarbon generation potential and the formation environment of a high mature marine source rock could be evaluated objectively through a palynological study.The source rock in Qixia Formation are dominated by amorphous organisms with high productivity,and was formed in far-continental shelf with anoxic environment, which provided good conditions for the development and preservation of hydrocarbon source rocks.The organic matters in Dalong Formation are also dominated by amorphous organisms,but the hydrocarbon generation potential is inferior to Qixia Formation.The source rock in Longtan Formation was formed in oxygen aeration continental shelf area,and the organic matters are dominated by coaly organisms and mainly of terrigenous input.The frequent change in sedimentary water is infavorable for the formation of the hydrocarbon source rocks.