关键词: 太平庄井, 地下流体, 综合研究

Abstract: Taipingzhuang observation well is one of the wells that has been observed for over ten years and has experienced some earthquake cases.In recent years,the ground water level has significantly fallen due to large amount exploitation of underground water,and especially geothermal exploitation around the Taipingzhuang observation well.This paper presents the analysis of the annual behavior of water level,water temperature,escaped gases and fault gases of the Taipingzhuang observation well,on the basis of the normal behavior in former years and the tectonic setting of the well.The analysis shows that the variation of water level and water temperature depends on the rainfall at the recharge area of the well,and the variation of water temperature is affected also by local rainfall.Especially,the withdrawal of newly drilled wells around the observation well greatly affects the variation of water level,water temperature and escaped gases of the observation well.After eliminating the effects of rainfall and human factors,the observed data of the Taipingzhuang well will still be useful for the prediction of seismic regime in Beijing region. After eliminating interference factors,the water level and water temperature of Taipingzhuang well for the year of 2002 was consistentwith the normal annual behavior of the well,and no significant anomalywas observed.The water level in 2002 was lower in winter and higher in summer and autumn,in consistence with the ordinary annual behavior of the well.However,the rise of water level of the well after the end of heating period in spring was very slow,and the risen water level was4m lower than the highest level in the same period of 2001.This might be attributed to the pervasive water level drop in Beijing region,and especially to the large amount exploitation of hot water around Taipingzhuang area. H₂ content of the escaped gases in the Taipingzhuang observation well begins to increase anomalously with the withdrawal of hot water in winter,and than decreases to normal value at the end of heating period in March.This phenomenon can be attributed to the following reasons:The large amount exploitation of hot water causes the significant drop of water level,which in turn causes the decrease of pore pressure in the layer;in this condition the gases will expand and H₂ may remove rapidly,causing the increase of H₂ content in escaped gases.In addition,the gases from the depth are concentrated mainly in the space above the aquifer,and the drop of water level will cause the escape of these stored gases,and hence the increase of H₂ content.

Key words: Taipingzhuang observation well, underground fluid, dynamic behavior