成岩阶段微生物作用及其油气地质意义

成岩阶段微生物发育及其对有机质的改造对于生物甲烷聚集、优质烃源岩形成具有重要意义。在综合近年对沉积成岩过程相关的微生物作用研究的基础上，以柴达木盆地三湖坳陷第四系为例，论述了成岩阶段微生物在生物甲烷生成、有机质富集保存、可溶有机质生成等方面的作用。柴达木盆地三湖坳陷第四系生物标志化合物降解参数与产甲烷菌特征标志物的关系，指示原始沉积有机质降解与甲烷菌发育，是第四系沉积物中生物气聚集的关键因素；与细菌来源生物标志化合物相对丰度的关系，反映成岩阶段微生物发育改变了原始有机质性质；与氯仿沥青“A”转化率以及饱和烃相对丰度的关系，表明微生物发育是第四系沉积物中可溶有机质的重要来源。

Effect of microorganisms during diagenesis and its significance on petroleum formation

The development of microorganisms in the diagenetic stage and their alteration on organic matter are of great significance for the generation and accumulation of biogenic methane and the formation of high quality hydrocarbon source rocks.Based on the comprehensive study on the effects of microorganisms related to deposition and diagenesis processes in recent years,the role of microorganisms on biogenic methane generation,organic matter enrichment and preservation,and soluble organic matter production during diagenesis were discussed,taking the Quaternary of the Sanhu Depression,Qaidam Basin as an example.The relationships of biodegradation parameters of biomarker compounds with methanogen markers indicates the biodegradation of original sedimentary organic matter and the development of methanogens,which are the key factors for the accumulation of biogenic gas in the Quaternary sediments in the Sanhu Depression,Qaidam Basin.The relationship with the relative abundance of bacterial biomarkers reflects the transformation of the property of original organic matter by microbial development in the diagenetic stage.The relationship with the fractional conversion of the chloroform bitumen “A” and relative abundance of saturated hydrocarbons suggest that the development of microorganisms is an important source of soluble organic matter in the Quaternary sediments.