The Combination Characteristics of the Biomarkers of Microbial Degradation of Organic Matter in LowEvolution SourceRock
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摘要: 研究了吐哈盆地低演化烃源岩有机质受到细菌微生物改造后其生物标志物的分布特征。结果表明:低演化有机质在经受细菌微生物作用时不同系列生物标志物的降解敏感性存在“类阶梯式”序列:正构烷烃>无环类异戊二烯烷烃>藿烷>甾烷>芳香烃。甾烷C29αββ/(ααα+αββ)和芳烃9MP/ΣMP是良好的细菌微生物作用有机质的敏感参数。同一烃源岩有机质的生物标志物参数出现:OEP2>OEP1(OEP1可能出现偶碳优势);藿烷C31αβ22S/22(S+R)>甾烷C29ααα20S/20(S+R);及甾烷C29αββ/(αββ+ααα)>C29ααα20S/20(S+R)等异常组合特征,可认为该源岩经历过较强烈的微生物作用过程,其降解程度可用每对参数比值的大小来判识,进而可将这些异常生标组合特征作为判识该地区有无微生物成烃(气、油)的依据。研究区源岩被微生物改造后改变了原始有机质的性质,使其生烃活化能大大降低,在低演化阶段即可生烃,从而有利于低熟油、气的生成。Abstract: Researched the distributing characteristics of biomarkers of lowevolution source rocks in TurpanHami basin, the organic matter has been transformed by microorganism. The result shows: The bacterium microorganism acting on deposit organic matter relative strength, there is a “quasistepwise” sequence to describe the general order of susceptibility of various biomarker compound classes to biodegradation, that is nalkanes > acyclic isoprenoids> hopanes >steranes> aromatic hydrocarbon, C29ββ/(ββ+αα) and 9MP/ΣMP are sensitive parameters to the reforming of bacteriummicroorganism effect on organic matter. The biomarkerparameters of the same source rock appear: OEP2>OEP1(perhaps OEP1<1,show even carbon number predominance), hopane C31αβ22S/22(S+R)>steraneC29αα20S/20(S+R), sterane C29αββ/(αββ+ααα)>C29αα20S/20(S+R) etc. abnormal combination characteristics of the biomarkers, suggests the source rock had experienced stronger bacterium–microorganism degradation process, and these ratios can be used to scale the extent of biodegradation,
as well as be further served as meaningful basis to judge whether the biogenic hydrocarbon (gas and oil) generated from the source rocks in the area. The characteristic of source rock organic matter would be changed by the reforming of bacterium microorganism in the study area, these changes will enable decreasing the activation energy of hydrocarbon generated, and they are favorable for lowmature gas(oil) generation. -

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