Xinjiang Petroleum Geology ›› 2008, Vol. 29 ›› Issue (4): 403-410.

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Carbon Isotope Types and Significances of Alkane Gases from Junggar Basin and Tarim Basin

DAI Jin-xing1, NI Yun-yan1, LI Jian2, HU Guo-yi2, ZHU Guang-you1   

  1. 1. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China;
    2. Langfang Branch, Research Institute of Petroleum Exploration and Development, PetroChina, Langfang, Hebei 065007, China
  • Received:2008-05-14 Published:2020-10-09

Abstract: The carbon isotope distribution pattern of alkane gases can be divided into three types: normal carbon isotopic distribution characterized by organic genetic alkane gas; negative carbon isotopic distribution characterized by inorganic alkane gas; reversal trend of alkane gas carbon isotope characterized by secondary modified gas. There exist both abundant primary coal-derived gases and oil-type gases in normal carbon isotope distribution and a lot of secondary organic genetic alkane gases in reversal trend of carbon isotope. There is no inorganic genetic alkane gas in primary negative carbon isotope distribution except for individual secondary modified negative carbon isotope derived from organic genetic alkane gases. The carbon isotopic reversal trend has four origins: 1) an admixture of gases from the same source but different stages or from different sources but the same types; 2) an admixture of coal-derived gas and oil-type gas; 3) microbial oxidation of some components of the alkane gases, and 4) an admixture of organic and inorganic alkane gases.

Key words: Tarim basin, Junggar basin, alkane gas, carbon isotope, type

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