南海南部曾母盆地新生界煤系烃源岩生油条件

Oil-generating potential of Cenozoic coal-measure source rocks in Zengmu Baisn,the southern South China Sea

在广泛调研前人研究的基础上,对曾母盆地新生界典型煤系烃源岩的有机地球化学、有机岩石学以及沉积成因特征进行了系统分析,进而探讨了该盆地煤系烃源岩的生油潜力。微观显微组分组成及成因分析,结合宏观沉积相研究,揭示出曾母盆地具有良好生烃潜力的下中新统煤系烃源岩发育于下三角洲平原带的红树林沉积环境中。对显微组分定量数据、基本生烃指标以及烃源岩热演化阶段的分析表明,该套煤系烃源岩具有在低熟阶段生油以及排烃的良好条件。另外,由于烃源岩中丰富的渗出沥青体生成而产生的内部增压,导致了大量相互连通的微裂隙发育,这有助于煤系烃源岩中析出油滴的汇聚以及排出。

The present paper discussed the oil-generating potential of Cenozoic coal-measure source rocks in Zengmu Basin by means of organic geochemical,organopetrological and sedimentological investigations on typical source rock samples.Integrated with the examination of depositional facies,compositional and genetic analyses of macerals indicated that Lower Miocene coal-measure source rocks with exceptional generative potential in Zengmu Basin were deposited in a mangrove depositional environment of a low-delta plain.And quantitative analyses of maceral assemblages,conventional hydrocarbon-generating parameters and investigations on the thermal evolution of source rocks showed that this suite of source rocks was of exceptional potential in generating and expulsing hydrocarbons at the low-mature stage.In addition,a large number of microfissures connecting with each other were well developed due to the elevated inner pressure resulting from the formation of many exsudatinites within source rocks,which favored the convergence and expulsion of oil drops excreted from source rocks.