原油不同极性含氮化合物的氮同位素组成特征  

Nitrogen Isotope Distribution Characteristics of Different Polar Nitrogen Compounds in Crude Oil

作　　者：徐学敏[1,2] 陈践发[2] 师生宝[2] 汪双清[1] 孙玮琳[1] 沈斌[1] 

机构地区：[1]国家地质实验测试中心,北京100037 [2]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249

出　　处：《矿物岩石地球化学通报》2017年第1期150-153,共4页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：中国地质调查局地质矿产调查评价项目(DD20160184);国家科技重大专项项目(2016ZX05034-03);国家自然科学基金项目(41572108)

摘　　要：氮是原油的重要组成元素,主要赋存在非烃和沥青质中,依据其极性差异分为碱性与非碱性2种类型。相较于其他组成元素,原油氮同位素的研究非常有限,不同极性含氮组分的氮同位素特征研究更是缺乏。本次研究应用杜马斯燃烧法原理,利用EA-IRMS连用技术测定了江汉油田6个原油样品不同极性含氮化合物的δ^(15)N和δ^(13)C。结果表明,不同极性含氮化合物的氮同位素组成具有明显的差异,碱性氮的δ^(15)N为9.7‰~11.8‰,明显轻于非碱性氮(11.4‰~14.5‰),原因可能是2种含氮组分的形成机制不同,碱性氮形成于成岩作用早期,δ^(15)值主要受原始母质的影响,而非碱性氮在热演化过程中的富集,氮同位素值更重,利用氮同位素有益于进一步明确原油中含氮化合物的演化机制及其地球化学意义。Nitrogen is an important element in crude oil. It mainly occurs in the nonhydroearbon and asphahene. It can be classified into basic nitrogen and non-basic nitrogen based on the polarity difference. Comparing to researches on other compositional elements of the crude oil, the research on nitrogen isotopes of crude oil is very limited with lack of the research on nitrogen isotopes of different polar nitrogen compounds in crude oil. In this work, nitrogen and carbon isotopes of different polar nitrogen compounds in six crude oil samples from the Jianghan oilfield in China were determined by using an elemental analyzer（EA） coupled directly to an isotope ratio mass spectrometer（IRMS） based on Dumas combustion method. The results show that there are obvious differences among nitrogen isotopes of nitrogen compounds with different polarities. The nitrogen isotopes of the basic nitrogen （ 9.7‰ -11.8‰） are obviously lighter than those of the non-basic nitrogen （ 11.4‰ - 14.5‰）. This may be caused by different formation mechanism of 2 kinds of nitrogen compounds. Nitrogen isotopes of basic nitrogen compounds, which were formed at early diagenetic stage, are mainly influenced by the original materials, whereas the nitrogen isotopes of non-basic nitrogen compounds, which were enriched in the thermal process of the late diagenetic stage, are enriched in 15N with the increasing maturity of organic matters. Nitrogen isotope is useful to further clarify the evolution mechanism and geochemistry features of nitrogen compounds in crude oil.

关 键 词：原油 氮同位素 杜马斯燃烧法 中性氮 碱性氮 

分 类 号：P618.13[天文地球—矿床学]