Isotopic composition charac-teristics and identification of immature and low-mature oils

作     者：XU Yongchang SHEN Ping LIU Wenhui GUAN Ping HUANG Difan 

作者机构：State Key Laboratory of Gas GeochemistryLanzhou Institute of GeologyChinese Academy of SciencesLanzhou 730000China Department of GeologyPeking UniversityBeijing 100871China Institution of Exploration&DevelopmentChina Petroleum&NaturalGas Corporation LimitedBeijing 100083China 

出 版 物：《Chinese Science Bulletin》 (CHINESE SCIENCE BULLETIN)

年 卷 期：2001年第46卷第22期

页      面：1923-1929页

核心收录：

学科分类：081803[工学-地质工程] 08[工学] 0818[工学-地质资源与地质工程] 

基　　金：This work was supported by the China Petroleum & National Gas Limited Corp. (Project No. 960006) the National Natural Science Foundation of China (Grant No. 49973010) 

主　　题：immature and low-mature oil isotope associated gas. 

摘      要：Isotopic composition characteristics and the significance of immature and low-mature oils are first systematically discussed. The carbon isotopes of the whole oil can be divided into two groups, one has δ13C main peak values ranging from -30‰ to -29 and the other from -27‰ to -25‰, they are related to lacustrine and salt-lake facies or swamp facies, respectively. The carbon isotopic fractionation among different group components is relatively small, usually less than 2‰ and the biggest difference in fractionation often occurs between saturated and aromatic fractions. Their δD values vary between -180‰ and -130‰. The main peak of their δD values concentrates between -170‰ and -150‰, suggesting a domination of lacustrine facies. However, the secondary peak ranges from -160‰ to -150‰, showing a frequent salinization of paleo-water bodies. The average δ13C values of the methane vary between -50‰ and -52‰, about 10‰ lighter than those of mature oils. There is a relatively good