新疆石油地质

›› 2015, Vol. 36 ›› Issue (1): 1-1.doi: 10.7657/XJPG20150103

• 论文 •    

羌塘盆地托纳木地区沥青脉地球化学特征

杜佰伟1，2，彭清华1，2，何江林1，2   

  1. (1.中国地质调查局 成都地质调查中心,成都 610081;2.国土资源部 沉积盆地与油气资源重点实验室,成都 610081)
  • 出版日期:2019-01-01 发布日期:1905-07-11

Geochemical Characteristics of Upper Jurassic-Lower Cretaceous Bituminous Vein in Tuonamu Area in Qiangtang Basin

DU Baiwei1,2, PENG Qinghua1,2, HE Jianglin1,2   

  1. (1.Chengdu Center of China Geological Survey, Chengdu, Sichuan 610081, China; 2.Key Laboratory for Sedimentary Basin and Oil-Gas Resources, Ministry of Land and Resources, Chengdu, Sichuan 610081, China)
  • Online:2019-01-01 Published:1905-07-11

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摘要： 在野外地质观察基础上，对羌塘盆地托纳木地区上侏罗统—下白垩统沥青脉开展了详细的有机地球化学特征研究，探讨了沥青脉有机母质来源及母质形成的沉积环境。沥青脉样品中检测出丰富的正构烷烃、类异戊二烯烃、萜类化合物和甾类化合物。正构烷烃主碳数分别为nC17或nC18，奇偶优势为0.81~1.10，Pr/nC17值为0.73~1.36，Ph/nC18值为0.80~1.66，Pr/Ph值为0.64~0.90. 萜类化合物以C30藿烷占优势的五环三萜烷为主，含有三环萜烷和伽马蜡烷。甾类化合物以规则甾烷为主，C27，C28和C29甾烷构成了不对称的“V”字型，C29甾烷ααα20S/C29甾烷ααα（20S+20R）和C29甾烷αββ/C29甾烷（ααα+αββ）的值分别为0.33~0.45和0.15~0.49. 饱和烃色谱-质谱特征表明，沥青脉有机母质来源于具有水生生物和高等植物的混合来源，揭示了沥青脉母质形成于一定盐度缺氧还原环境。油源对比显示沥青脉与索瓦组泥页岩的饱和烃、萜烷、甾烷等生物标志物参数具有一致性，说明它们具有亲缘关系，也证实了该地区烃源岩具有较好的生烃潜力。

Abstract: Based on the field observation, this paper studied in detail the geochemical characteristics of the Upper Jurassic-Lower Cretaceous bituminous vein in Tuonamu area of Qiangtang basin and discussed the bituminous kerogen origin and the forming environment. And abundant biomarkers such as n-alkanes, isoprenoids, terpanes and steranes were detected from the samples by GC and GC-MS. The carbon number of n-alkane appears as nC17 and nC18, with OEP of 0.81~1.10, Pr/nC17 of 0.73~1.36, Ph/nC18 of 0.80~1.66 and Pr/Ph of 0.64~0.90. The terpanes are dominated by pentacyclic triterpane with tricyclic terpane and gammacerane, in which C30 hopanes are dominant. The steranes are dominated by regular steranes, in which C27-C28-C29ααα20R distributes in asymmetric “V” shape. The C29ααα20S/(20S+20R) value ranges from 0.33~0.45 to 0.15~0.49, respectively. The GC-MS characteristics of saturated hydrocarbons show that the bituminous kerogen is originated from the mixed sources of phytoplankton and higher plants, revealing such a kerogen is formed in anoxic reducing environment with some salinity. The oil source correlation indicates that the bituminous vein’s biomarkers are consistent with those of the Suowa shale in terms of saturated hydrocarbons, terpanes and steranes, confirming that they have close affinity and the hydrocarbon source rocks in this area have better hydrocarbon generation potentials

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