油气包裹体分子组成的热释—色谱—质谱分析

Pyrolysis-gas chromatography-mass spectrometry analyses of oil-bearing fluid inclusions composition

陈彦鄂 张志荣 GREENWOODPaul

CHEN Yan'e ZHANG Zhirong GREENWOOD Paul

中国石化 油气成藏重点实验室, 江苏 无锡 214126 中国石化 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214126 西澳大学, 澳大利亚 珀斯 WA6009

Key Laboratory of Petroleum Accumulation Mechanisms, SINOPEC, Wuxi, Jiangsu 214126, China Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China University of Western Australia, Perth, WA 6009, Australia

油气包裹体分子组成对油气成藏研究来说具有较大的应用价值。由于油气包裹体中所含物质的量不能满足常规化学仪器分析的要求，因此通常需要研发定制仪器且实现难度较大，从而限制了该技术的推广应用。采用热释-色谱-质谱法对澳大利亚Halibut油田原油的人工合成包裹体、澳大利亚Jabiru油田和塔河油田油气包裹体样品进行了烃类组成分析。正构烃类，单、双以及三环芳烃等组分能够被有效检测到，检出化合物的最高碳数超过了C30。该方法与其他手段分析结果具有较高的可比性，Jabiru油田包裹体热释-色谱-质谱分析与包裹体分子组成离线分析（MCI，Molecular Composition of Inclusion）的结果对比显示，芳烃化合物的成熟度参数仅有微小的差异，两种方法获得的包裹体烃类成熟度均明显低于产出原油，印证了油气流体在被捕获形成包裹体后能够避免后期改造的影响。热释法作为一种通用的常规方法，同样适用于油气包裹体的分析，相比于其他手段，该方法更加便捷。

The molecular compositions of oil-bearing fluid inclusions (FIs) are valuable for the research of oil and gas accumulation; however, due to the very trace amount of materials included, the requirements of commercial instruments cannot be satisfied and thus custom designed instruments were needed for this method, which is difficult to be achieved and the application for the molecular composition of FIs have been limited. In this paper, three samples of oil-bearing FIs were analyzed by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) to obtain their hydrocarbon composition. The first sample was a synthetic inclusion prepared by the occlusion of a small amount of crude oil from the Halibut oil field, the second sample was from Australian Jabiru oil field and the third sample was collected from the Tahe oil field in the northwestern China. A diverse range of aliphatic compounds, including n-alkanes, mono-, di- and tricyclic aromatic hydrocarbons and other components have been successively detected from these materials of which, the n-alkanes were monitored up to carbon numbers over C30. Also, the results showed that the method introduced here gave comparable molecular characteristics with data obtained from other traditional methods. The mature degree calculated from Py-GC-MS is very close to that of MCI method. However, it is also notable that the thermal maturity parameters calculated from the results of inclusion analysis were much lower than those of crude oil, indicating modification caused by late-stage alteration to oils in reservoir. As a conventional and easy performed analytical method specially designed for the degradation of macromolecule, the Py-GC-MS demonstrated here is also suitable for the analysis of FIs.

https://doi.org/10.11781/sysydz202105915