元坝气田天然气组分与同位素特征分析  

Gas Components and Isotopic Characteristics of Yuanba Gasfield

作　　者：秦绪乾 QIN Xuqian

机构地区：[1]中国石化勘探分公司,四川成都610041

出　　处：《天然气技术与经济》2018年第4期16-19,81,共5页Natural Gas Technology and Economy

基　　金：国家科技重大专项"南方海相碳酸盐岩大中型油气田分布规律及勘探评价"(2017ZX05005003)的部分成果

摘　　要：对川北元坝气田长兴组天然气地球化学特征分析结果显示:天然气以烃类气体为主,甲烷含量占绝对优势,干燥系数大,非烃组分以H_2S和CO_2为主;烃类气体δ^(13)C表现为正碳同位素序列特征,主要是由于高热演化程度与强硫酸盐热化学还原反应作用影响。通过天然气乙烷、储层沥青与川北地区海相各套烃源岩δ^(13)C对比分析认为,该区气源应来自二叠系烃源层。元坝气田内部不同井区非烃组分含量变化较大,开展元坝气田不同井区天然气组分与同位素相关性与分布规律分析,认为元坝气田Ⅰ井区硫酸盐热化学还原反应作用强度较元坝气田Ⅱ井区大。After analyzing gas geochemical characteristics of Changxing Formation,Yuanba gasfield,northern Sichuan Ba-sin,it is shown that,natural gases are dominated by hydrocar-bon gases in chemical composition with methane the most,and featured by higher drying coefficient,moreover non-hydro-carbon components are mainly composed of sulfur and carbon dioxide;and 8I3C value of hydrocarbon gases exhibits a fea-ture of normal carbon isotope sequence due to two effects of high thermal evolution and thermochemical sulfate reduction(TSR).In addition,after a correlation of ethane in natural gas,bitumen in reservoirs,andδ13C of various source rocks,it is deemed that gases in this study area should be originat-ed from Permian source beds.For non-hydrocarbon compo-nents in different well blocks,their content varies a lot.Oth-er analysis on gas components,and isotopic correlation and distribution also shows the TSR stronger in Yuanba I well block than in Yuanba II block.

关 键 词：元坝气田 天然气组分 同位素 硫酸盐热化学还原反应 

分 类 号：P618.13[天文地球—矿床学]