本源微生物降解辽河原油的非烃分子结构变化

Changes in molecular structure of non-hydrocarbons in the Liaohe crude oil by the degradation of indigenous microorganisms

利用高效本源降解菌在不同时间范围内对辽河油样进行了微生物降解模拟实验,以研究不同降解程度原油分子结构的变化规律。微生物作用前后原油样品做族组分分离及进一步的中性氮化合物和酸性化合物分离,然后对其不同组分进行色谱质谱分析和红外光谱分析。结果表明,辽河油样中的非烃化合物经微生物作用以后,正构一元酸含量随降解时间的增加而增加,且变化幅度逐渐增大;五环三萜类羧酸中C28组分和莫烷酸系列随着降解时间的增加含量上升;轻度的微生物降解作用对咔唑、甲基咔唑、二甲基咔唑等化合物没有明显影响,中等强度降解具有一定的影响;从胶质、沥青质红外光谱图看出,微生物能够降解该原油胶质、沥青质。侧链长度随降解程度增加而变短;芳香环结构抗微生物降解能力强,缩合程度变化不大;而取代基上的烷烃易被微生物氧化,氧化程度随降解程度增加而增加,产生酸类、醚类物质。探讨原油微生物降解中非烃化合物结构及其地球化学特征对石油勘探开发都有重要指导作用。

In the microbial degradation simulation experiment, a Liaohe oil sample was treated by the selected highly efficient degrading bacteria from the oil for different times to study the variation in molecular structure of crude oil with degradation degree. Group components of the oil before and after bacteria degradation were separated and the neutral nitrogen compounds and acidic compounds were obtained by further isolation. Then different fractions were analyzed using gas chromatography-mass spectrometry and infrared spectrometry. The results show that the concentration of n-monoacids （as methyl esters） in oil increase gradually with degradation time, and the C2s component of carboxylic acid in pentacyclic triterpenoid and moretanoids acid series increase too. Mild microbial degradation of oil has no significant effect on carbazole, methylcarbazole, and dimethyl carbazole compounds, while medium degradation has a certain impact on them. The infrared spectrograms of resins and asphaltenes show that bacteria are able to degrade these components in the crude oil. The length of side-chain in resins and asphaltenes shortens with microbial degradation. Aromatic compounds display less variation in condensation degree due to their strong resistance to microbial degradation. While the substituene is sensitive to microbial oxidation and produces acids and ethers, and the degree of oxidation increases with degradation. Therefore, it plays an important role in the exploration and development of crude oil to study the variation in structure and geochemical characteristics of non-hydrocarbon components in crude oil during microbial degradation.