原油中甾烷的生物降解模拟实验研究

STUDY ON THE SIMULATED BIODEGRADATIED STERANE IN CRUDE OIL

通过喜氧细菌对原油的模拟生物降解实验,以及对模拟产物的饱和烃色谱—质谱分析,对原油饱和烃中规则甾烷和重排甾烷的降解作用进行了研究。研究结果显示,规则甾烷先于重排甾烷发生生物降解,甾烷降解由易到难的顺序为C27>C28>C29。在甾烷被大量降解前,20S/(20S+20R)(甾烷异构化作用)等生物标记化合物的成熟度指标基本无变化,但某些用于油源对比、母源和沉积环境研究的生物标记化合物参数可能会发生变化,如:规则甾烷/17α(H)-藿烷、C27-C28-C29甾烷、C27-C28-C29重排甾烷和重排甾烷/规则甾烷等。

The biodegradation of regular sterane and rearranged sterane in crude oil was studied on the basis of simulated biodegradation experiment to the crude oil. The biodegradation products were analyzed by GC-MS. Research shows that the biodegradation of regular sterane is early than that of rearranged sterane. The biodegradation ability of sterane is C27〉C28〉C29. Before the great biodegradation of the sterane, those maturity indicators such as isomerization of C29 steranes at C20 vary slightly. But some biomarker indicators used for the researches on oil-source correlation, oil source and sedimental environment will probably change. These indicators include ratio of regular steran to 17α（H）-hopane, C27-C28- C29 sterane, C27 - C28 - C29 rearranged sterane, ratio of rearranged sterane to regular sterane, and so on.