羌塘盆地二叠系白云岩油苗地球化学特征及意义

发布时间：2018-05-10 21:15

本文选题：生物标志化合物 + 单体碳同位素　；参考：《沉积学报》2017年03期

【摘要】：通过采集羌塘盆地中央隆起带二叠系展金组白云岩油苗及烃源岩样品,对其族组成、饱和烃、芳烃色谱—质谱以及单体碳同位素进行了研究,并进行了油源对比。研究结果表明:白云岩油苗中饱和烃含量最高,其次为非烃,芳烃和沥青质含量较低,饱芳比大于1;白云岩油苗的正构烷烃主要为前高单峰型分布特征,碳数分布范围n C_(15)~nC_(36),主峰碳为nC_(17)~nC_(20),nC_(21)-/nC_(22)+值为1.0~4.56,C_(27)-C_(28)-C_(29)规则甾烷表现为不规则的"V"型的分布并且C29甾烷占优势,升藿烷从C_(31)~C_(35)均有检出,显示出白云岩油苗的生烃母质主要来源于藻类和细菌等低等水生生物;白云岩油苗的Pr/Ph值为0.91~1.30,伽马蜡烷指数值为0.42~0.88,三芴系列化合物中以硫芴含量最高(平均67.39%)而氧芴含量(平均7.89%)较低,4-MDBT/DBT比值为0.97~4.26,(2+3)-MDBT/DBT值为0.37~1.62,表明白云岩油苗生烃母质为形成于具有一定盐度还原环境为的海相页岩;白云岩油苗的OEP值接近平衡值1,甾萜烷异构参数C_(29)ααα20S/ααα(20S+20R)、C_(29)αββ/(ααα+αββ)和C_(31)22S/(22S+22R)等接近或达到平衡值,芳烃标志物成熟度参数MPI_1、F_1和4,6/1,4-DMDBT计算出的等效镜质体反射率表明白云岩油苗为成熟原油。白云岩油苗的生物标志物和展金组泥岩具有较好对比性,反映了白云岩油苗主要来源于展金组烃源岩;其单体碳同位素与二叠系展金组烃源岩分布形式和变化趋势基本相似,但也有一定的差异,反映了其具有混合来源的特点。
[Abstract]:The oil seedlings and source rocks of the Permian Yanjin formation in the central uplift zone of Qiangtang Basin were collected, their group composition, saturated hydrocarbons, aromatic hydrocarbon chromatography-mass spectrometry and single carbon isotopes were studied, and the oil sources were compared. The results show that the saturated hydrocarbon content of dolomite oil seedling is the highest, the second is non-hydrocarbon, the content of aromatics and asphaltene is lower, the ratio of saturation to aromatics is more than 1, and the normal alkane distribution of dolomite oil seedling is mainly prehigh-single-peak type. The carbon number distribution range n / c / C / T / C / T / C / C / C / C number distribution range n / C / T / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / S / C / C / C / S / C / C / C / C / S / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / T / C / C / C / C / C / C / C / C / C / C / C / C / It is shown that the hydrocarbon source material of dolomite oil seedling is mainly derived from algae and bacteria. The Pr/Ph value of dolomite oil seedling was 0.91 ~ 1.30, and the gamma-waxy index was 0.42 ~ 0.88. The highest content of thiofluorene (average 67.39) and the lower ratio of 4-MDBT / DBT of dolomite oil seedling were 0.371.62 and 0.371.62 respectively, which indicated that the hydrocarbon source material of dolomite oil seedling was the highest (average 67.39), and that the ratio of 4-MDBT / DBT was 0.371.62, which indicated that the hydrocarbon source material of dolomite oil seedling was the parent material of hydrocarbon generation of dolomite oil seedling. Formed in marine shale with certain salinity reduction environment; The OEP value of dolomite oil seedling was close to or reached equilibrium value, and the OEP value of dolomite oil seedling was close to or reached equilibrium value. The equivalent vitrinite reflectance calculated by the maturity parameters MPI1 / FST1 and 466 / 14-DMDBT showed that dolomite oil seedling was mature crude oil. The biomarkers of dolomite oil seedling and the mudstone of Yanjin formation have a good comparison, which shows that the dolomite oil seedling mainly comes from the source rock of Yanjin formation, and its single carbon isotope is similar to the distribution form and variation trend of the source rock of the Permian Yanjin formation. However, there are some differences, reflecting the characteristics of mixed sources.
【作者单位】：中国地质调查局成都地质调查中心;国土资源部沉积盆地与油气资源重点实验室;
【基金】：中国地质调查局项目(DD20160159,1212011221114,GZH201400301) 国家自然科学基金(41172098)~~
【分类号】：P618.13

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