摘要:
马朗凹陷的原油类型可以划分为3大类，Ⅰ类原油来自二叠系芦草沟组，Ⅱ类原油来自石炭系哈尔加乌组，Ⅲ类原油为Ⅰ与Ⅱ类原油的混源油。通过断裂活动强度、垂向输导断裂与烃源岩的匹配关系的研究，结合原油含氮化合物的分析资料，分析了马朗凹陷油气的垂向运移特征。研究表明，断层的断裂活动强度控制着油气的垂向运移能力，垂向输导断裂与烃源岩相匹配时，烃源岩生成的油气才能向上运移至上覆地层聚集成藏。二叠系芦草沟组烃源岩厚度中心附近的垂向输导断裂断穿侏罗系，所以，芦草沟组烃源岩生成的Ⅰ类原油可以运移至侏罗系聚集成藏，而石炭系哈尔加乌组烃源岩附近的断裂大都未断至二叠系和侏罗系，所以哈尔加乌组烃源岩生成的Ⅱ类原油未能运移到侏罗系聚集成藏，而主要在石炭系成藏。与断裂输导分析相配合，含氮化合物可以很好示踪油气的垂向运移方向，沿断裂从深层到浅层，原油含氮化合物总浓度逐渐降低，1,8DMC/1,3DMC或1,8DMC/2,4DMC值增大。
Abstract:
There are three types of crude oil in the Malang sag, Santanghu Basin. Type Ⅰ oil is from the source rocks of Permian Lucaogou Formation. Type Ⅱ oil is from the source rocks of Carboniferous Haerjiawu Formation and type Ⅲ oil is mixed source oil of type Ⅰ oil and type Ⅱ oil. Based on the study of the intensity of faults activity and the matching relationship between vertical transporting faults and the source rock, and then combined with the analysis data of nitrogen compounds, vertical migration characteristics of the oil in the Malang sag are studied in this paper. The research results are as follows. Firstly, the vertical migration ability of the oil is controlled by the intensity of faults activity, and the oil can accumulate in the overlying strata by migrating when the vertical transporting faults match the source rock well. When there are only vertical transporting faults or there is only source rock, oil can not accumulated in the overlying strata. The Jurassic was broken through by the vertical transporting faults nearby the thickness center of the Permian Lucaogou Formation source rock, so type Ⅰ oil which was generated by the source rock of the Lucaogou Formation could accumulate in the Jurassic through migration. The Permian and Jurassic were not broken by most faults nearby the Carboniferous Haerjiawu Formation source rock, so type Ⅱ oil which was generated by the source rock of the Carboniferous Haerjiawu Formation could not accumulate in the Permian and Jurassic, and it only accumulated at the top of Carboniferous. Besides, combined with the analysis of transporting faults, nitrogen compounds can trace hydrocarbon vertical migration well. The absolute concentration of nitrogen compounds in the crude oil is gradually reduced. And nitrogenshielded isomers are more enriched than parts of nitrogenshielded isomers and nitrogenexposed isomers from the deep to the shallow strata. For example, the value of 1,8DMC/1,3DMC and 1,8DMC/2,4DMC both are increased from the deep to the shallow strata. These parameters all trace the hydrocarbon vertical migration through the transporting faults from the deep to the shallow strata well.
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