准噶尔盆地乌夏地区生物降解原油中饱和烃组成解析

运用全二维气相色谱/飞行时间质谱(GC×GC/TOFMS)结合全二维气相色谱/氢火焰离子检测(GC×GC/FID)实现了对准噶尔盆地乌夏地区不同生物降解程度原油饱和烃复杂混合物成分的分析研究,提升了对生物降解原油组成及成因机理认识。结果显示:①乌夏地区生物降解原油中不可识别混合物主要由烷基取代环状化合物及其同系物组成,这些环状化合物主要以六元环为基本单元,包括单环烷烃(类胡萝卜烷)、双环烷烃(十氢化萘,脱-A,B环-甾烷)、三环烷烃(菲满类、三环萜烷、断甾烷)和金刚烷类、四环烷烃(甾烷、断藿烷、四环萜烷)和五环烷烃(藿烷、25-降藿烷)等六大类化合物;②不同生物降解原油中饱和烃总量变化不大,饱和烃中不同族系化合物随着生物降解作用增强呈现此消彼长的变化规律,在重度生物降解阶段,双环烷烃存在大量同系物及同分异构体,可能是微生物作用新生成的化合物,并且由于自身较强的抗生物降解能力,使双环烷烃成为饱和烃的优势成分,占饱和烃总量的50%左右,而多环烃类化合物含量随着生物降解程度逐渐增加,主要是由抗降解能力相对较强的高环数化合物的逐渐富集形成。

Study on composition of saturated hydrocarbon complex mixtures in biodegraded crude oil from Wuxia area,Junggar Basin

In this paper,saturated hydrocarbons in biodegraded crude oil from Wuxia area in Junggar Basin were analyzed by two dimensional gas chromatography coupled with time-of-flight mass spectrometry(GC×GC/TOFMS)and two dimensional gas chromatography coupled with flame ionization detector(GC×GC/FID),which increased understanding of the composition and genetic mechanism of biodegraded crude oil. The result shows:(1)the major components of complex mixtures in biodegraded heavy oil from Wuxia are cyclic com-pounds with different carbon number alkyl groups and isomers. These cyclic compounds mainly consist of sixmembered ring as the basic unit,including six types:Monocycloalkanes(carotenoid),bicycloalkanes(deca-hydronaphthalene,de-A,B-ring-steranes),tricycloalkanes(perhydrophenanthrenes,tricyclicterpanes,seco-steranes)and adamantanes,tetracycloalkanes(steranes,secohopanes,tetracyclic terpanes)and pentacycloalkanes(hopanes,25-norhopanes);(2)the total content of saturated hydrocarbons does not change much,and different families of saturated hydrocarbons show a change with the increase of biodegradation. In the stage of severe biodegradation,dicycloalkanes have a large number of homologues and isomers that are not detected in normal crude oil. These compounds may be newly formed by microbial action,and due to their strong biodegradability,bicycloalkanes become the dominant components of saturated hydrocarbons,accounting for about 50% of the total saturated hydrocarbons. Anti-biodegradation ability of polycyclic hydrocarbon compounds is relatively strong,resulting in an increase in content of polycyclic hydrocarbon compounds with degree of biodegradation.