Carbon and Hydrogen Isotopic Composition of Individual nAlkanes for Crude Oil from North Margin of Qaidam Basin

Key words: 
• n alkanes /
• carbon isotopes /
• hydrogen isotopes /
• biological markers /
• north margin of Qaidam Basin

Abstract:  Using GC/C/MS online carbon isotope analysis technique, we obtained the carbon and hydrogen isotopic composition of individual nalkanes for crude oil from different tectonic belts of the north margin of Qaidam Basin. The carbon and hydrogen isotopic composition of nalkanes for crude oil samples can be used to analyze genetic type of crude oil and oilsource correlation. The analytical results indicate that the δ13C and δD values of nalkanes in soluble organic matter  ranging between 36‰～25‰ and 180‰～110‰,   respectively. Through comparing, it is found that there exist significant differences between the carbon and hydrogen isotopic composition of nalkanes for crude oil from different tectonic belts. By the combination of δ13Cnalkanes (30‰), δDnalkanes (140‰), and distribution pattern isotopic curve,  the carbon and hydrogen isotopic composition can be divided into different distribution patterns. Using these patterns can discriminate hydrocarbon generation material and  sedimentary environment.