碳稳定同位素比质谱法对中东原油的鉴别

采用气相色谱/稳定同位素比质谱法(GC/IRMS)对具有相似化学特征的科威特、阿联酋、沙特以及伊拉克产的原油中正构烷烃(n-C10～n-C24)的碳稳定同位素比δ(13C/12C)进行了分析,通过原油单体烃分布趋势对比、主成分归类、同位素比值与诊断比例(Diagnostic ratio,DR)联用等方法对4种原油进行了鉴别。结果表明,沙特与伊拉克所产原油、科威特与阿联酋所产原油的单体烃分布趋势相似,且主成分相近,采用同位素比值与诊断比例联用法成功地对它们进行溯源。结果表明,沙特与伊拉克所产原油的δ(13C/12C)值以及DR(n-C17/pristane(Pr)、n-C18/phytane(Ph)、Pr/Ph)相近,说明它们具有相同的母质类型及沉积环境,属于同一种原油;科威特与阿联酋所产原油的δ(13C/12C)值相似,而DR明显不同,表明其母质类型及成熟度不同,属于不同种原油。本研究所采用的分析技术也适用于其它原油的溯源研究。

Identification of Middle East Crude Oil Using Stable Carbon Isotope Ratio Mass Spectrometry

Gas chromatograph/stable isotope ratio mass spectrometry(GC/IRMS) was used to analyze the stable carbon isotope ratio(δ(13C/12C)) of n-alkanes(n-C10～n-C24) in crude oil with similar features from Kuwait,United Arab Emirates,Saudi Arabia and Iraq.Four crude oils were identified by the comparison of individual hydrocarbon distribution,the clustering of principal components,the combination of δ(13C/12C) and diagnostic ratio(DR).The results show that individual hydrocarbon distribution and principal component of Saudi Arabia and Iraq oil are similar,and so are to Kuwait and United Arab Emirates oil,but it is still hard to identify them by these proofs.The combination of δ(13C/12C) and DR can solve this problem successfully.Saudi Arabia and Iraq oil with similar δ(13C/12C) and DR(n-C17/Pr,n-C18/Ph(phytane value),Pr/Ph) have the same matrix and sedimentary environment,so they belong to the same type of crude oil.However,Kuwait and United Arab Emirates oil with similar δ(13C/12C) and different DR have different matrix and maturity,so they belong to diffe-rent type of crude oil.The analytical method in this study could also be applied to identify crude oils.