Abstract: Tarim Basin is the largest inland oil and gas basin in China. The main source rocks of oil in the basin are still controversial.
Oil-oil correlation can discern the relationship between crude oils and identify the geochemical characteristics of different types of
crude oil, which is an effective method to address this problem. The crude oil from the Awatage Formation of the Middle Cambrian and
the Xiaoerbulake Formation of the Lower Cambrian in Zhongshen-1 Well and Zhongshen-1C Well serve as important end-member oils
for oil-oil comparison. In this study, trace elements characteristics of the two kinds of Cambrian crude oil and a variety of light crude oil
were investigated, and results indicate the studied oil can be classified into two groups in terms of trace elements ratios including Cr/V,
Ni/Mn and Ni/Mo. The crude oil in group I have lower Cr/V ratios and higher Ni/Mn, Ni/Mo ratios than the crude oil in group II, which
may indicate that the source rocks for group I were deposited in a relatively more reducing environment. The classification results are
consistent with previous studies based on organic geochemistry, indicating that inorganic geochemical indicators can also be used as
indexes for crude oil classification, and have great potential for further application.

Key words: Tarim Basin, Cambrian crude oil, trace elements, oil-oil correlation