高 玲，林元武，杨明波

（北京市地震局，北京 100038）

延庆五里营井稀有气体地球化学特征①

高 玲，林元武，杨明波

（北京市地震局，北京 100038）

延庆五里营井逸出气体中主要组分是N2，微量组分含有He，CH4，Rn，CO2，Ar等。N2／Ar值为46．3，3He／4He为2．4Ra，说明井热水中有深部幔源组分的加入；CH4含量为2．2%，CO2（TCD）为4．9mg／L，显示了强还原环境下的热水释放活动，这与延怀盆地微量气体以还原性气体释放为主的气体背景场相符。五里营井气体释放更倾向于是热储库型气体释放而非断裂型释放，这可通过氦气动态观测及2次大震前后流体前兆氦气浓度异常释放得到体现。热储库型气体释放中深部气体上升进入热储并改变整个热储组成的时间较断裂型晚，消失的时间也会晚得多，这与处于八宝山断裂带的大灰场井氦气释放特征存在明显差异。五里营井气体释放特征与该区域地质、地球物理特征相符。

五里营井；稀有气体；还原性气体释放；成因；热储库型

Abstract：The release gas in Wuliying well，Yanqing county of Beijing，is N2，with minor gases He，CH4，Rn，CO2，Ar．The ratio of N2／Ar is 46．3and ratio of3He／4He is 2．4Ra，which show that it mixted by deep mantle－origin conponents．The facts of CH4content is 2．2%，and CO2（TCD）is 4．9mg／L show the hot water release activity under strong reduction environment，which corresponds the gas－release background field characteristicsed by reduction－oriented gas release activity in Yanhuai basin where the well located in．It also shows that the gas release in Wuliying well tends to be a themal－reservoir type，rather than a fault type，reflected by Helium observation and the abnormal release of Helium density before and after two strong earthquakes．It suggests that the time of deep gas with themal－reservoir type entering themal－reservoir lags than the fault type，and disappears much later than fault type does also．This is different from the gas release characteristics in Dahuichang well which located near Babaoshan fault at Fengtai area of Beijing．

Key words：Wuliyng well；Minor gases；Reduction－oriented gas release；Origin；Thermal－reserivor type

0 前言

稀有气体氦及其同位素是反映深部流体活动的灵敏组分。由于观测条件限制，He气观测开展的较少。随着技术的进步，2007年在地质背景特殊的点陆续开展了He气观测。北京地区选在了延庆五里营井和丰台大灰厂井，分别于2008年2月正式投入观测。He气观测对于了解区域深部气体背景动态变化，开展气体地球化学“一井多测项”观测，实施多指标综合判定地震前兆有重要意义。本文对五里营井稀有气体及He同位素组成特征进行分析，通过与大灰厂氦气释放动态观测对比，对五里营井稀有气体释放机理进行初步分析。……