氩同位素用于库车坳陷天然气主力气源岩判识  

Identification of main gas source in Kuqa depression using argon isotope ratios

作　　者：张殿伟[1] 刘文汇[2] 郑建京[1] 王晓锋[1] 南青云[1] 

机构地区：[1]中国科学院兰州地质研究所气体地球化学重点实验室 [2]中国石油化工股份有限公司石油勘探开发研究院,北京100083

出　　处：《地球化学》2005年第4期101-105,共5页Geochimica

基　　金：国家重点基础研究发展计划项目(2001CB209102)。~~

摘　　要：稀有气体是天然气中指示其地球化学特征的重要组分,放射成因氩(Arr)的年代积累效应广泛应用于同位素定年和天然气的气源对比。本文系统地讨论了40Ar的形成机理及其运移进入气藏的过程,利用40Ar的母体元素K在煤和煤系泥岩中的丰度差异,分析了以煤和煤系泥岩为母源的天然气40Ar/36Ar同位素组成上的不同,并利用这种差异对煤系中煤岩或煤系泥岩为源岩的天然气藏的主力源岩进行了判识,继而建立了利用氩同位素组成判识煤系烃源岩主力源岩的方法。利用此方法对塔里木盆地库车坳陷三叠系—侏罗系煤与煤系泥岩互层的烃源岩进行了探讨,数学计算结果表明该区主力源岩为煤系泥岩,煤对天然气藏的贡献较小。Rare gas is an important constituent for indicating natural gas geochemical characteristics. Radiogenic argon (40Arr) is widely applied to isotope chronology and gas and source rock correlation. K, the parent element of 40Arr, has different abundance in coal and argillite, which can be used in analyzing the difference between 40Ar/36Ar values of natural gases produced from coal and argillite, and identifying the main gas source in coal source rocks. In this paper, the forming mechanism of 40Arr and its process of entering into gas pool are discussed, on the basis of which a method for identification of main gas source is developed. Using this method the interbedding source rocks of Triassic-Jurassic coal and argillite are studied in the Kuqa depression, Tarim Basin. The results of calculation indicate that the main gas source is the argillite in Triassic-Jurassic coal measures and coal makes a little contribution to natural gas reservoir.

关 键 词：氩同位素组成 气源对比 煤 碳质泥岩 库车坳陷 塔里木盆地 

分 类 号：P593[天文地球—地球化学] P597[天文地球—地质学]