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.