基质镜质体成烃动力学特征研究

干酪根、煤以及显微组分生烃过程中的动力学参数(如活化能分布特征等)是其内部分子结构的宏观反映,据此可以判断有机质内部成键特征,评价生油门限、生油高峰,计算不同温度范围油气生成量等。笔者利用岩石热解仪(Rock-Eval型)对贵州水城含树皮体煤中的主要组成——基质镜质体的成烃动力学特征进行了研究,并与树皮体、丝质体进行比较,结果表明,基质镜质体的平均活化能为200kJ/mol,大于树皮体的平均活化能(177kJ/mol),而小于丝质体的平均活化能(324kJ/mol),由此推断,在相同的热演化条件下,基质镜质体、树皮体、丝质体三者的生烃顺序为树皮体→基质镜质体→丝质体。从基质镜质体生烃活化能分布特征图上可以看出,基质镜质体有4次主要生烃期,其对应的活化能分布范围及产烃率分别为191.25—192.5kJ/mol、12.19%,195—196.25kJ/mol、7.25%,197.5—198.75kJ/mol、39.82%,216.25kJ/mol、18.64%,据此可以认为:基质镜质体主要由4种不同类型键组成。在活化能191.25—198.75kJ/mol范围内,基质镜质体的累计生烃率达60%左右,这说明基质镜质体产烃较集中(在较短的地质剖面或温度范围内形成大量烃类物质),其含量高(煤岩三大组分之一),因此对煤成烃资源有较大的贡献。

THE KINETIC FEATURES OF HYDROCARBON GENERATION OF DESMOCOLLINITE

The kinetic parameters of hydrocarbon generation from coals or kerogens,can indi cate the structure of their internal molecular,which govering the thermal breakdown of kerogen have been extensively studied by laboratory experiments,so as to derive values that can subsequently used in basin modeling,for simulating kerogen maturation and predicting the time and extent of oil generation.In this paper,Rock Eval Ⅱ were carried out on desmocollinite,which isolated from Lepinite,Late Permian coals in Shuicheng,Guizhou Province,southern China.The first purposes of these studies is to discuss the relationship between the chemical structure and kinitic parameters of desmocollinite.The seconds is to research the regular pattern of hydrocarbon generation of desmocollinite.The determination of the kinetic parameters show that the characteristics of activation engergies distribution is related with chemical structures,ad desmocollinite are composed of four chemical bond at least.The average activation energy of barkinite,desmocollinite and fusinite are 177 kJ/mol,200 kJ/mol and 360 kJ/mol respectively,so at the same condition,the order of oil formation of the three macerals is barkinite→desmocollinite→fusinite. The studies will help to explore oil generayion from Late Permian coals in southern China.