严重生物降解稠油油源关系精细对比新方法研究

Oil-source correlation has important scientific significance and practical value for determining hydrocarbon source rocks, indentifing new oilfield position and predicting oil scale. It has effectively guided the exploration of the conventional oil and gas resources. Presently, the exploration of oil and gas fields for heavy oil and other unconventional oil and gas resources is one of the hot topics at home and abroad. However, the severe biodegradation have been taken place in heavy oil, some biomarkers are not been used to recognize oil-oil correlation, oil-source correlation. The reason is that the biomarkers have already been destroyed. Thus, looking for new biomarkers that can represent the original information of of heavy oil is imminent. In our previous work, the ultrasonic wave technology was used to extract biomarkers from the asphaltene inclusions of the crude oils which are not susceptible to be biodegraded and compared with crude oils.The results showed that the steranes,terpanes and triaromatic sterane of the asphaltene inclusions and the crude oil are very similar. As a result, our results suggest that the ultrasonic wave technology may be an appropriate method of extracting the biomarkers of the asphaltene inclusions.Therefore, this project will ascertain the mechanism of ultrasound extraction, research the asphaltine structure, optimize the conditions of extraction, determine the best approach of extracting the biomarkers of the asphaltene inclusions. Furthermore, analyse comprehensively the asphaltenes of different parent material sources and biodegradation degree, summariz the relationship of the distribution characteristic and the isotopic composition between biomarkers of the asphaltene inclusions and outside of the asphaltene, a set of oil-source correlation method applying for the severe biodegradation heavy oils will be established.

稠油等非常规资源的勘探是国内外勘探热点。油源对比对于确定新含油气层位、评价盆地资源量并指导勘探至关重要。严重生物降解油中的生物标志化合物已遭细菌破坏，从而失去了指示原始生源特征的功能。因此，寻找其油源对比新方法迫在眉睫。我们前期工作观察到，超声波提取稠油沥青包裹烃可获得完整的正构烷烃、甾、萜烷及芳烃组份，而且沥青质包裹组分与游离态组分中的生物标志化合物甾、萜烷及三芳甾烷分布特征非常相似，与降解程度无关。因此超声波提取包裹在沥青质大环内的生物标志化合物有可能是进行严重降解稠油油源对比的有效方法。本项目拟对沥青质结构、包裹烃赋存状态、超声萃取机理及萃取条件优化的研究，确定超声波技术提取稠油沥青质包裹组份的最佳方案，并对不同母质来源、不同降解程度的原油沥青质进行系统研究，总结沥青质大环包裹的生标与可溶有机质中游离态生标的分布特征及同位素关系，建立一套新的稠油油源精细对比新方法。

油源对比及烃源岩演化程度的划分是指导盆地油气勘探、进行油气资源量评价的关键因素，对于油气勘探具有重要的意义。而大多数稠油由于受到微生物降解作用的影响，部分生物标志化合物已遭细菌破坏, 致使原油物性发生剧变, 这给利用常规生物标志物参数进行油-油、油-源对比、成熟度及沉积环境的判识带来了一定的困难，成为油源研究领域的难题之一。本项目采用超声萃取技术，本着沥青质包裹体具有保护其内部小分子不受微生物破坏而具有代表原油最初信息的思想及增强超声波强度可以产生空化效应，从而有效地打破沥青质包裹体，释放原始生标这一原理。以胜利油田及新疆油田稠油为研究对象，对严重生物降解原油中沥青质进行了抽提纯化和超声萃取, 获得了沥青质中未降解的生物标志化合物，其结果显示沥青质包裹体组分中甾、萜烷与原油组分的甾、萜烷非常相似, 而与生物降解程度无关, 表明此方法可完全用于强烈生物降解原油的油-油对比和油-源对比研究, 从而建立了沥青质中生物标志化合物有效提取技术，为严重生物降解原油和烃源岩油源对比的研究提供了一个新的途径。