吐哈盆地中下侏罗统煤系地层源岩和油中饱和烃的GC/MS分析

Saturated hydracarbon of coal,carbonaceous mudstone and oils from the Lower Jurassic coal measures in the Turpan basin were studied,and biomarker characteristics and coal thermal maturity analyzed to draw the following conclusions. There are many similar biomarker characteristics between oil from middl-lower Jurassic of Turpan Basin and coal and carbonaceous mudstone in the same strata. They all contain specific r-lupane, I-norbietane, C24-tetracyclic and high content of C29-steranes. These characteristics suggest that they have similar matter source of the organic matter derived from matter with abundant high plants. Meanwhile, biomarkers often used to indicate depositional environments characterized by high Pr/Ph ratio, little or no gammacerane and high abundance dibenzofurans, such biomarker distributions are indicative of suboxic and freshwater environment. Although coal and carbonaceous mudstone remain in lower thermal maturity (Ro=0.47-0.53), but C29-ββ/(αα ββ) sterane ratio (0.294-0.489) and bezohopane are detected. Because these ferture are related to bacterial activity, bacterial degrdation of organic matter maybe take an important role in coal-derived oil.     

成岩阶段微生物作用及其油气地质意义

成岩阶段微生物发育及其对有机质的改造对于生物甲烷聚集、优质烃源岩形成具有重要意义。在综合近年对沉积成岩过程相关的微生物作用研究的基础上,以柴达木盆地三湖坳陷第四系为例,论述了成岩阶段微生物在生物甲烷生成、有机质富集保存、可溶有机质生成等方面的作用。柴达木盆地三湖坳陷第四系生物标志化合物降解参数与产甲烷菌特征标志物的关系,指示原始沉积有机质降解与甲烷菌发育,是第四系沉积物中生物气聚集的关键因素;与细菌来源生物标志化合物相对丰度的关系,反映成岩阶段微生物发育改变了原始有机质性质;与氯仿沥青“A”转化率以及饱和烃相对丰度的关系,表明微生物发育是第四系沉积物中可溶有机质的重要来源。     

微生物改造有机质与未―低熟石油的形成

对部分淡水和咸水环境中非海相沉积物及未―低熟烃源岩进行了微生物类发酵实验。发酵后生烃潜力增强,烃类含量增加,烷烃奇偶优势降低。发酵样品中,生物构型的藿烷消失,地质构型藿烷大量出现,各项异构化参数接近、达到终点值。说明温度不是影响藿烷成熟度指标的唯一因素。在低演化阶段,微生物参与和改造有机质,可以使有机质直接转化为石油烃类。     

甘肃窑街中侏罗世油页岩单体烃碳同位素分析对比研究

n-Alkanes is widely used in the study of geologic body, which occupies 50%-80% of the saturated hydrocarbons commonly. The biogenetic implication of these compounds hold a very important value for the evaluation of all source rock, so it is used as biomarker to backward the biogenetic source of deposit organic matter. In order to find the difference of the isotopic composition of different organic compounds before and after complexion the oil shale in Yaojie, Gansu sample was performed by 5 molecular sieve adsorptipon to study the variation of the isotope compositions of n-alkanes, isoalkanes and cyclanes. On the basis of the previous work, the mini-sized Soxhlet extraction set with a hot reflux device was adopted to enhance the recovery of samples and diminish the loss of light components in the tested samples.