Oil & Gas Geology ›› 2015, Vol. 36 ›› Issue (4): 573-580.doi: 10.11743/ogg20150406

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Evolution patterns and their significances of biomarker maturity parameters—a case study on liquid hydrocarbons from type Ⅲ source rock under HTHP hydrous pyrolysis

Sun Lina1,2, Zhang Zhongning1, Wu Yuandong1,2, Su Long1, Xia Yanqing1, Wang Zixiang1,2, Zheng Youwei1,2   

  1. 1. Key Laboratory of Petroleum Resources, Gansu Province/Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2014-09-26 Revised:2015-06-20 Online:2015-08-08 Published:2015-08-28
  • Contact: 张中宁(1964—),男,副研究员,油气地球化学。E-mail:ldlab@ns.lzb.ac.cn。 E-mail:ldlab@ns.lzb.ac.cn

Abstract:

High temperature and high pressure hydrous pyrolysis experiments were conducted on type Ⅲ source rocks from Well Tao 10 in Liaohe Basin under various conditions to investigate the role of biomarker maturity parameters at different thermal evolution stages.The expelled oils collected from these experiments were separated into saturated hydrocarbons, aromatic hydrocarbons, non-hydrocarbons and asphaltene, and the saturated fractions were analyzed by GC/MS.Taking the simulation temperature as the scales of maturity, the biomarkers that are indicative of thermal maturity evolution were detected from n-alkane, isoprenoid alkane, tricyclic terpane, tetracyclic terpane, hopane and sterane, and their parameter index were also calculated.Based on the different sensitivities of different biomarkers to thermal action, the ratio of different biomarkers may reflect different thermal stages.With the simulation temperature increasing, the hopanes may be turned into tricyclic terpanes, Tm may be turned into Ts, and the configurations of isomers will be transformed from 22R to 22S, thus the ∑tricyclic terpane/∑hopane, Ts/Tm and C31-hopanes 22S/(22S+22R) may be good indicators of thermal stages.But in the stage of maturity to over-maturity, the C24-tetracyclic terpane/∑hopanes, C30βα-moretane / C30αβ-hopane and C29-sterane ββ/(αα+ββ) are more suitable indicators.Therefore, samples at different thermal evolution stages have their own optimal biomarker assemblages providing a theoretical basis for determining thermal evolution stage of source rocks by using maturity parameters in the study area.

Key words: thermal maturity parameter, pyrolysis, liquid hydrocarbons, GC/MS analysis, biomarker, source rock

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