作　　者： ; ;

机构地区： 中国科学院广州地球化学研究所

出　　处： 《天然气地球科学》 2005年第2期224-228,共5页

摘　　要： 氮气( N2 )是天然气中最常见的非烃组分之一。天然气中的N2 依其成因与来源特征总体可分为大气来源、与生物作用有关的来源和与岩浆活动有关的地壳深部或地幔来源等。根据天然气中氮的赋存状态和一些地球化学特征,并结合塔里木盆地的火山活动史,对塔里木盆地天然气中氮气成因机理进一步综合分析后认为:在白垩系以上(浅部)的油气藏内,天然气中氮的平均含量低于5 % ,主要以大气来源为主,勘探风险较低;对于白垩系以下至志留系(中部)的油气藏来说,天然气含氮量平均为2 0 .3% ,来源较复杂,以混源(深部源和生物作用来源)为主,勘探风险居中;对于奥陶系以下(深部)的油气藏,天然气中氮含量离散度较大,最低为2 .8% ,最高达5 5 .3% ,低氮来源以生物作用为主,高氮来源以地壳深部火山活动或结晶基底来源为主。 Molecular nitrogen is one of most common non-hydrocarbon components in natural gas reservoirs. The origin of molecular nitrogen in natural gas can be classified to be three types, according to its origin, that is, atmospheric nitrogen resource, bio-genesis resource and deep crust and upper-mantle resource correspondingly. Based on the nitrogen preserve, distribution and some geochemistry properties, and combined with the volcanic history of Tarim basin, the genesis of molecular nitrogen in natural gas has been comprehensively analyzed in the paper. The study shows:① the gas pool in the shallow part (such as Cretateous), the average relative abundance of nitrogen is lower 5 percent, and its main origin is from atmospheric nitrogen, and its exploration risk coefficient is relatively lower;② the middle part (such as Carboniferous, Permian), its origin of nitrogen is relatively complex, which main resource is from the deep mantle or bio-genesis. The average relative abundance of nitrogen is about 20 percent, and its exploration lies in between; ③ the deep part gas pool (such as Ordivician), the average relative abundance of nitrogen is variable, thepoor-nitrogen gas pool, its main resource is from bio-genesis, while the rich-nitrogen gas pool, its main resource is from the deep mantle and is related with the metamorphic rock, its exploration risk coefficient is relatively higher.

关 键 词： 塔里木盆地 天然气 形成原因 勘探风险 氮气 来源特征 火山活动

领　　域： [石油与天然气工程] [天文地球] [天文地球]