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准噶尔盆地南缘地区原油分布广泛,不同地区原油具有不同的地球化学特征。按照碳同位素与生物标志物组成特征可以分为4种典型类型:1第1类原油典型特征是碳同位素组成轻,全油δ13 C值通常小于-29‰,正构烷烃分子碳同位素分布比较平缓,δ13 C值通常小于-28‰,含有较丰富的β-胡萝卜烷,甾烷以C28、C29规则甾烷为主,重排甾烷低,伽马蜡烷含量变化较大;2第2类原油碳同位素组成重,全油δ13 C值通常在-28‰~-26‰,正构烷烃分子碳同位素分布比较平缓,δ13 C值通常大于-28‰,Pr/Ph比值高,甾烷以C29规则甾烷和重排甾烷为主,三环萜烷以C19为主,伽马蜡烷含量很低;3第3类原油碳同位素组成轻,全油δ13 C值通常小于-29‰,C9以上正构烷烃分子碳同位素分布随碳数增高大幅下降,δ13 C值在-27‰~-34‰,Pr/Ph比值小于1.0,C27、C28、C29甾烷呈“V”型分布,异胆甾烷、重排甾烷含量高,Ts、C29Ts、C30重排藿烷高,Ts/Tm>1,伽马蜡烷含量高且具有两个异构体,甾/萜烷比值高;4第4类原油碳同位素组成重,全油δ13 C值通常在-28‰~-26‰,C9以上正构烷烃分子碳同位素分布随碳数增高下降幅度大,δ13 C值在-23‰~-29‰,C27、C28、C29甾烷呈“V”型分布且以ααα-20R为主,异胆甾烷丰度低,甲藻甾烷尤为丰富,三环萜烷以C19为主,伽马蜡烷含量较低。
The crude oil in the southern margin of Junggar Basin is widely distributed, and the crude oil in different areas has different geochemical characteristics. According to the characteristics of carbon isotope and biomarker can be divided into four typical types: 1 Class 1 crude oil is characterized by light carbon composition, oil δ13 C value is usually less than -29 ‰, n-alkanes carbon isotope distribution relatively flat , δ13C value is usually less than -28 ‰, rich in β-carotenoid, sterane mainly C28, C29 regular steranes, rearrangement sterane low, gamma-wax content changes significantly; 2 Category 2 The δ13C value of the whole oil is usually -28 ‰ ~ -26 ‰, and the δ13C value is usually larger than -28 ‰. The ratio of Pr / Ph is high, and the content of sterane in C29 Regular steranes and rearrangement steranes, mainly C19 of tricyclic terpanes and very low contents of gamma-alkanes; 3) the carbon isotope composition of the third-type crude oil is light, the δ13C value of the whole oil is usually less than -29 ‰, and the C9 The above-mentioned n-alkanes showed a sharp decrease in carbon isotopic distribution with increasing carbon number. The δ13C value ranged from -27 ‰ to -34 ‰, the Pr / Ph ratio was less than 1.0, and the C27, C28 and C29 steranes showed a “V” Isocholestane, high content of rearrangement sterane, Ts, C29Ts, C30 rearrangement hopane high, Ts / Tm> 1, high gamma-wax content and two isomers, 4 Category 4 The δ13C value of the whole oil is usually -28 ‰ ~ -26 ‰, and the distribution of carbon isotopes of n-alkanes above C9 decreases with increasing carbon number. The δ13C value is -23 ‰ ~ -29 ‰, C27, C28, C29 steranes were “V” type distribution and the main ααα-20R, isocholesterol low abundance, dinoflastone is particularly rich, tricyclic terpane to C19-based, gamma wax Lower alkane content.