准噶尔盆地乌夏地区稠油生物降解特征

准噶尔盆地乌夏地区稠油主要分布在风城油田,由于受到较强烈的生物降解作用影响,密度和粘度很高,正构烷烃和无环类异戊二烯烷烃严重降解,胡萝卜烷缺失,藿烷含量部分降解或严重降解,甾烷和重排甾烷部分降解,而三环萜烷含量、孕甾烷和升孕甾烷含量很高,m(Ts)/m(Tm)平均值为3.55。根据稠油的正构、异构烷烃降解程度、生物标记化合物和25-降藿烷系列化合物的降解程度以及三环萜烷含量和孕甾烷含量,将乌夏地区稠油生物降解作用级别划分为6级,并以此为依据将乌夏地区稠油分为6种类型。

A Study on Biodegradation of Heavy Oil in Wu-Xia Area, Junggar Basin

The heavy oil mainly distributes in Fengcheng oilfield of Wuerhe-Xiazijie area in Junggar basin. Affected by the biodegradation, the density and viscosity of heavy oil are very high, normal paraffin hydrocarbons and pentacyclic isoprenoid paraffin hydrocarbons are subjected to serious degradation, so are partial hopanes, steranes and homosteranes, and free carotene, while tricyclic terpanes, pregnanes and homopregnanes are in high content, with high Ts/Tm value of 3.55. This paper presents the six ranks of biodegradations of heavy oils in Wu-Xia area, and accordingly gives six types of heavy oils in this area, based on the degradations of normal- and iso-alkanes, biomarkers and 25-norhopanes as well as the contents of tricyclic terpanes and pregnanes.