苏北盆地古近系泥页岩有机质孔发育特征及影响因素

通过对苏北盆地古近系泥页岩研究并结合美国Marcellus页岩研究成果,定义有机质孔的概念,归纳有机质孔的类型及特征,探讨有机质孔发育的影响因素并总结有机质孔演化规律。结果表明:有机质孔泛指在有机质内部或边界处发育并与有机质具有成因联系的所有孔隙,包括原生有机质孔和次生有机质孔两类;有机质孔形态多样,分布具有非均质性,特别当有机质孔大量发育时,其内部结构是具有层状格架的似蜂窝状连通体;温度、上覆岩层压力、无机矿物和流体是影响有机质孔发育的外部条件,有机质类型、有机质成熟度和有机质含量是控制有机质孔发育的内部因素;苏北盆地古近系泥页岩实际样品和热模拟实验样品中有机质孔均表现出阶段性演化特征,这与干酪根热解生烃过程中的组构演化和生烃机制密切相关。

Characteristics and influencing factors of organic-matter pores in paleogene shale, Subei Basin

Based on the study of Paleogene shale in Subei Basin, and combining results of the Marcellus shale, this paper defined the concept of organic-matter pore, summarized its types and characteristics, discussed its influencing factors and finally concluded evolution rule of organic-matter pore. The results show that organic-matter pores generally refer to pores which are within or at the boundary of organic matter and are genetically associated with it, and they include primary and secondary organic-matter pores. Organic-matter pores display various shapes and are distributed heterogeneously. Especially when they are well developed, the internal structure is a honeycomb connecting component in the layered framework. Temperature, overburden pressure, inorganic mineral and fluid are the external conditions influencing the development of organic-matter pores and organic matter type, while maturity and content are the internal factors controlling the development of organic-matter pores. Organic-matter pores of both Paleogene shale samples in Subei Basin and the thermal simulations have the characteristics of episodic evolution, which is closely related to the fabric evolution and hydrocarbon-generating mechanism during the process of hydrocarbon generation from Kerogen.