Secondary accumulation of hydrocarbons in Carboniferous reservoirs in the northern Tarim Basin, China
Secondary accumulation of hydrocarbons in Carboniferous reservoirs in the northern Tarim Basin, China
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DOI：
10.1016/j.petrol.2013.01.005
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发表时间：
2013-02
影响因子：
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通讯作者：
G. Zhu;Shuichang Zhang;J. Su;Shucui Meng;Haijun Yang;Jianfeng Hu;Yongfeng Zhu
中科院分区：
文献类型：
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作者：
G. Zhu;Shuichang Zhang;J. Su;Shucui Meng;Haijun Yang;Jianfeng Hu;Yongfeng Zhu
塔里木盆地北方石炭系已发现多个油气田。不同类型油气田产出的油气在物理和地球化学性质上存在很大差异。然而，尽管它们已成为勘探的焦点，但它们的成因和成藏过程却没有得到很好的研究。通过对油气的地质、地球化学综合分析，认为石炭系原油是由中上奥陶统烃源岩生成，奥陶系古油藏运移而来，在晚海西造山运动（约250 Ma）之前发生生物降解而生成不同类型的稠油，是次生油藏。燕山运动以来（约86- 94 Ma），沿着库车前陆盆地的快速形成，石炭系构造由南倾逐渐反转为北倾，形成了石炭系鼻状圈闭。在反转过程中，断层起着连接下伏奥陶系储层与石炭系储层的运移通道作用。喜马拉雅运动晚期（20- 2 Ma），塔北东部奥陶系烃源岩被埋藏，达到了较高的成熟度，生成了天然气，在研究区东部形成了天然气成藏，发现了天然气和凝析油。通过生物标志物组成、流体包裹体均一温度和自生伊利石K-Ar定年分析，揭示了中石炭统油气的成藏过程。因此，石炭系油气次生聚集的结论对塔北方油气勘探具有重要意义。
Many oil and gas fields have been discovered in Carboniferous in the northern Tarim Basin. The oils and gases produced from the fields show great differences in their physical and geochemical properties. However, their origin and accumulation process have not been well studied even as they become a focus of exploration. Through comprehensive geological and geochemical analysis of the oils and gases, it is recognized that the oils were generated from Mid-Upper Ordovician source rocks, migrated from paleo-oil-accumulations in Ordovician, and were biodegraded to produce different heavy oils before the late Hercynian orogeny (about 250Ma), so that the oils in the Carboniferous are secondary oil accumulations. Since the Yanshan orogeny (about 86–94Ma), along with the quick formation of the Kuqa foreland basin, Carboniferous structures were reversed gradually from south dip to north dip, resulting in the Carboniferous nose-shaped traps. During the reversed, faults acted as migration paths connecting underlying Ordovician reservoirs to Carboniferous reservoirs. During the late period of the Himalayan orogeny (20-2Ma), the Ordovician source rocks were buried so that this achieved level high maturity and generated gas in the eastern part of North Tarim, which resulted in gas accumulations in the eastern part of the studied area, where gas and condensate oil were discovered. The accumulation process of the secondary Carboniferous oil and gas was demonstrated by biomarker compositions, homogeneration temperatures of fluid inclusions and authigenic illite K–Ar dating analyses. Therefore, this conclusion of secondary accumulations of oil and gas in the Carboniferous reservoirs is significant for oil and gas exploration in the northern Tarim.