单体烃类包裹体在油气地球化学中的应用——以塔河油田为例

Application of single hydrocarbon inclusions in petroleum geochemistry:A case study of the Tahe oilfield

利用近年来发展的烃类包裹体研究新方法,综合分析了塔河油田油气成藏期次与油气来源特征。结果表明,塔河油田具有多期油气充注特征,其中海西中期和喜马拉雅晚期占优势,单体烃类包裹体激光剥蚀在线成分分析表明,早期原油(黄色荧光包裹体)具有饱和烃色谱呈双峰型、芳烃含量较高的特征,属于成熟度相对较低的中质原油;而晚期原油(蓝色荧光包裹体)具有饱和烃呈单主峰型、芳烃含量较低的特征,属成熟中晚期轻质原油。结合研究区原油的来源或烃源岩沉积环境、成烃生物、成熟度、运移距离和成藏过程及时间,推测早期原油主要来源于下寒武统—下奥陶统优质烃源岩,晚期原油主要来自上奥陶统碳酸盐岩烃源岩。

The hydrocarbon accumulation period and petroleum source characteristics in the Tahe oilfield were discussed using the newly developed methods for hydrocarbon inclusion analyses. The results confirmed that there were many stages of hydrocarbon accumulation in the Tahe oilfield, especially predominated by the Middle Hercynian and the Late Himalayan. The online laser ablation compositional analyses of single hydrocarbon inclusion showed that the early oil （yellow fluorescing inclusion） was characterized by bimodal n-alkane distribution and higher aromatic component content, belonging to medium crude oil with relatively lower maturity. In contrast, the late oil （blue fluorescing inclusion） was featured by unimodal n-alkane distribution and lower aromatic component content, belonging to late light crude oil at the middle-late mature stage. Based on the petroleum source or sedimentary environment of source rocks, hydrocarbon-forming organisms, maturity, migration distance, accumulation process and period, the early oil was suggested mainly from -C1-O1 excellent source rocks and the late oil was mainly from O3 carbonate source rocks.