热解轻烃的组成及地球化学意义

源岩样品在绝氧条件下加热,进行人工热演化,演化产物用低沸点溶剂萃取分离出C₅—C₁₀的轻质烃类化合物,这些轻质烃类化合物称为热解轻烃。经毛细色谱分析,热解轻烃中有100余种化合物。根据化学热力学原理,轻烃化合物的生成、消失或相互转化,与岩样中有机质的生源物质、受热条件及环境有密切关系。本研究通过5个不同有机质类型的源岩样品的热解轻烃的组成分析,归纳和整理了轻烃组成随源岩沉积环境、有机质类型及热演化水平而变化的规律,并提出了若干试用参数。 

COMPOSITION OF LIGHT HYDROCARBON PYROLYSATES AND ITS GEOCHEMICAL SIGNIFICANCE

Under anoxytropic conditions, source rock samples were heated tosim-ulate their thermal evolution. The light hydrocarbon compounds (C₅-C₁₀) extracted from the pyrolysis products using low boiling point solvent are defined as light hydrocarbon pyrolysates.Gas chromatography shows that there are more than 100 compounds in light hydrocarbon pyrolysates. With the view of chemical thermodynamics, the generation, disappearance and intertransformation of light hydrocarbons are closely related to the source materials, the conditions and thermal environments of organic matter. By the determinations on source rock samples with five organic types, we draw some conclusions that the compositions of light hydrocarbon pyrolysates will vary with the sedimentary enviroments of mudstone, organic types and the degree of thermal evolution. Several trial parameters are also proposed in the paper.