产甲烷条件下稠油沥青质厌氧降解规律研究

Methanogenic degradation of hydrocarbons has attracted world-wide attention for the potential application to residual oil recovery in deep subsurface oil reservoirs. The metabolism mechanisms of anaerobic biodegradation of saturated and aromatic hydrocarbons in crude oils have been well documented. However, little is known about the methanogenic biodegradability of asphaltene that present an extremely complex molecular structure of oils. At present, it is not clear which compounds of asphaltenes can be degraded under methanogenic condition. In this proposal, asphaltenes from heavy oils ranged from 5-20˚API are extracted and used as carbon sources respectively, a highly-enriched methanogenic consortium capable of heavy oil degradation which has been subcultured for over eight years in our group is selected as the inoculum. Methane potential from different asphaltenes is evaluated under strict anoxic conditions. The asphaltenes during different incubation times are collected for subsequent analysis. The shift of element compositions, stable carbon isotopes and NSO-compounds of asphaltenes during different methane production phase are analyzed. Furthermore, the asphaltene molecular structure are characterized by nuclear magnetic resonance, flash pyrolysis-gas chromatography- mass spectrometry, and thermally assisted hydrolysis and methylation-gas chromatography–mass spectrometry. This study can provide a theoretical basis for biodegradation mechanism research of heavy oils, and also provide references for application of “biodegradation of residual oil to methane” in the future.

利用厌氧产甲烷菌将地下油藏难以开发利用的残余油原位转化为甲烷进行气态开采，是当前国际关注的前沿课题。国内外学者系统研究并逐步揭示了原油饱和烃和芳香烃组分的生物降解产甲烷规律。但是对分子量更大、结构更复杂的沥青质组分的研究报道却极其有限，目前还不清楚在原油厌氧降解产甲烷过程中，沥青质哪些组分发生了什么样的改性过程。本项目以课题组传代培养八年的稳定稠油厌氧降解产甲烷菌系为接种物，抽提不同稠油(5-20˚API)中的沥青质作为碳源，进行厌氧模拟培养，分析沥青质的生物气化潜力；收集不同培养阶段的沥青质，分析其元素组成、稳定碳同位素值和含N、S、O化合物的组成，阐明沥青质降解过程中的组分变化特征；采用核磁共振、瞬时热解和热辅助甲基衍生化色质谱技术，分析沥青质厌氧降解过程中官能团和结构的变化特征。本项目的顺利实施，为深入开展稠油生物降解机理研究提供基础，也为将来的“残余油气化”工程研发提供指导。

利用厌氧产甲烷菌将地下油藏难以开发利用的残余油原位转化为甲烷进行气态开采，是当前国际关注的前沿课题。国内外学者系统研究并逐步揭示了原油饱和烃和芳香烃组分的生物降解产甲烷规律。但是对分子量更大、结构更复杂的沥青质组分的研究报道却极其有限，目前还不清楚在原油厌氧降解产甲烷过程中，沥青质哪些组分发生了什么样的改性过程。本项目以课题组传代培养八年的稳定稠油厌氧降解产甲烷菌系为接种物，以不同原油作为碳源，进行厌氧模拟培养，分析石油烃的生物气化潜力；收集不同培养阶段的沥青质组分，阐明沥青质降解过程中的组分变化特征；采用瞬时热解和热辅助甲基衍生化色质谱技术，分析沥青质厌氧降解过程中官能团和结构的变化特征。研究表明，沥青质组分也发生了厌氧降解。对于沥青质组分的抗微生物降解能力，含有C-C、醚键的化合物强于氢键、酯键结合的化合物。本项目的顺利实施，为深入开展稠油生物降解机理研究提供基础，也为将来的“残余油气化”工程研发提供指导。