准噶尔盆地西北缘二叠系稠油地化特征及成因探讨

DISCUSSION ON THE GEOCHEMICAL CHARACTERISTICS AND GENESES OF PERMIAN VISCOUS OILS AT THE NORTHWESTERN EDGE OF JUNGGAR BASIN

本文通过对准噶尔盆地西北缘断裂下盘斜坡区五区南油气区二叠系乌尔术组（P2w）稠油的地球化学性质的分析发现，该稠油具有酸值低、凝固点和含蜡量较高，烃类客正构烷烃、缺乏含氧官能团和非选择性报失等特殊性质，与断裂上盘浅层次生氧化型稠油成因明显不同。根据油气的分布和各项地化特征，认为蒸发分馏作用是导致该区原油稠变的主要原因。

By analysing the geochemical characteristics of viscous oils from Permian Wuerhe Formation (Pzw) in the southern oil/gas region of V zone within faulted footwall slope area at the northwestern edge of Junggar Basin, it is discovered that the viscous oils have the special properties of low acidity, higher solidifying point and waxy content, alkane-bearing hydrocarbons, oxygen-bearing functional group lacking, unselective losses etc. and have obviously different geneses from secondary oxidized viscous oils in faulted upper plates- Based on the distribution and each geochemical character of hydrocarbons, it is considered that evapofractionation is the major reason to bring about the consistency changes of crude oils in this area.