甲、乙烷碳同位素用于判识天然气成因类型的讨论  

The application of methane and ethane carbon isotopes as an identification index for gas origin study

作　　者：韩中喜[1,2] 李剑[2] 垢艳侠[2] 严启团[2] 王淑英[2] 李谨[2] 刘金丰 葛守国[2] 

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油勘探开发研究院廊坊分院,河北廊坊065007 [3]中国石油集团渤海钻探工程有限公司第二录井分公司,河北任丘062550

出　　处：《天然气地球科学》2016年第4期665-671,共7页Natural Gas Geoscience

基　　金：国家科技重大专项"中国大型气田形成条件;富集规律及目标评价(二期)"(编号:2011ZX05007)资助

摘　　要：随着天然气勘探不断向深层发现,高—过成熟天然气越来越多,早期基于成熟—高成熟天然气所建立的用甲、乙烷碳同位素判识天然气成因类型的指标或图版不断显示出一系列的问题。为完善甲、乙烷碳同位素判识指标或图版,采集了中国7个含气盆地近200多口井的天然气样品,分别开展了天然气组分和烷烃碳同位素分析,并对部分气井的天然气样品开展了天然气汞含量分析,研究表明对于大多数天然气来说用乙烷碳同位素δ^(13)C_2=-28‰或-29‰作为划分煤型气和油型气的界限是合理的,但对于部分演化程度较高的天然气来说还需要结合甲烷碳同位素进行综合判断。在用甲、乙烷碳同位素判断天然气类型的图版中,煤型气和油型气的划分界限为δ^(13) C_2=-(10.2δ^(13)C_1+1 246)/29.8,当δ^(13)C_2>-(10.2δ^(13)C_1+1 246)/29.8时,天然气类型为煤型气;当δ^(13)C_2<-(10.2δ^(13)C_1+1 246)/29.8且δ^(13)C_1>-55‰时,天然气类型为油型气;当δ^(13)C_1<-55‰时为生物气。With the development of natural gas exploration into the deep zone,high-over mature natural gas is becoming more and more common.Previous index or chart for identification of natural gas genetic type based on mature-highmature natural gas is showing some problems.In order to improve this index or chart,the authors collected natural gas samples from more than 200 wells of 7basins in China.The compositions and hydrocarbon isotopes of these samples were analyzed,and some of them were measured for mercury content.The research shows that for most of the natural gas,using ethane carbon isotopeδ^132=-28‰ or-29‰ as the genetic type identification index to distinguish coal type gas and oil type is reasonable,but this is not applicable for the high-mature gas.It is necessary to combine methane and ethane carbon isotope to identify the genetic type of the gas.On the identification chart,the line for dividing coal type gas and oil type gas would beδ^13〈2=-（10.2δ^131＋1 246）/29.8.Whenδ^132〉-（10.2δ^131＋1 246）/29.8,the genetic type of the gas would be coal type,whenδ^132〈-（10.2δ^131＋1246）/29.8andδ^131-55‰,the genetic type of the gas would be oil type,and whenδ^131-55‰,the genetic type of the gas would be biogas.

关 键 词：甲烷 乙烷 碳同位素 天然气 成因类型 判识图版 

分 类 号：TE122.1[石油与天然气工程—油气勘探]